Co-reporter:Li-Feng Fang, Bao-Ku Zhu, Li-Ping Zhu, Hideto Matsuyama, Shuaifei Zhao
Journal of Membrane Science 2017 Volume 524() pp:235-244
Publication Date(Web):15 February 2017
DOI:10.1016/j.memsci.2016.11.026
•Two new PMMA-g-PEG copolymers are synthesized.•PVC/PMMA-g-PEG blend membranes show excellent antifouling properties.•Effect of coagulation media on membrane antifouling performance is studied.•Blend membranes prepared in water show ~100% fouling reversibility.Two new amphiphilic copolymers poly(methyl methacrylate-graft-poly(ethylene glycol) methacrylate) (PMMA-g-PEG) are synthesized and blended into polyvinyl chloride (PVC) to prepare membranes in different coagulation media (water and ethanol) via the non-solvent induced phase separation method. The prepared membranes are characterized by X-ray photoelectron spectroscopy, proton nuclear magnetic resonance, scanning electron microscopy, atomic force microscopy and water contact angle measurement. Their separation performance and fouling resistance (by protein adsorption and foulant filtration) are also compared. It is found that the membrane hydrophilicity is significantly increased by blending amphiphilic copolymer due to the introduction of hydrophilic poly(ethylene glycol) (PEG) segments of the copolymer. The membranes formed in water have more desirable structures (i.e., smoother surfaces and higher porosity) and better performance (i.e., higher permeability and rejection to bovine serum albumin) compared with those formed in ethanol. The amphiphilic copolymer blended membranes formed in the water coagulation bath exhibit excellent antifouling properties, in particular, showing ~100% fouling reversibility. Therefore, blending amphiphilic copolymers and selecting water as the coagulation media can be effective strategies to develop high performance antifouling membranes.
Co-reporter:You-Zhi Song, Xin Kong, Xue Yin, Yin Zhang, Chuang-Chao Sun, Jia-Jia Yuan, Baoku Zhu, Li-Ping Zhu
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2017 Volume 522(Volume 522) pp:
Publication Date(Web):5 June 2017
DOI:10.1016/j.colsurfa.2017.03.023
•A novel tanning-inspired two-pot coating process is proposed.•The modified polyproplyene membrane showed superhydrophilicity and underwater superoleophobicity.•This treatment takes only about 15 min and is scalable in practical oil/water emulsions separation with low cost.In this work, a novel two-pot coating process that facilely transform polypropylene (PP) microfiltration membrane hydrophobicity into superhydrophilicity and underwater superoleophobicity was reported. Tannic acid (TA) and ferric ions (FeIII) were selected as organic ligand and inorganic cross-linker, respectively. Compared with the membrane modified by the one-pot method, the two-pot treated substrate has uniformly distributed coatings, better wettability, higher water permeability (7092 L m−2 h−1 bar−1, which is 4.5 times higher than that of the one-pot modified membrane), and excellent oil/water emulsions separation performance. This treatment only took about 15 min and the underwater superoleophobicity was well maintained even after rigorous long-term washing operation. More importantly, both the remaining solutions of TA and FeIII could be recycled and reused easily in the next two-pot coating process. Such a rapid, green, and cost-effective modification method highlights its potential for practical application in oil/water emulsions separation.Download high-res image (211KB)Download full-size image
Co-reporter:Xin Kong;Ze-Lin Qiu;Chun-Er Lin;You-Zhi Song;Li-Ping Zhu;Xiu-Zhen Wei
Journal of Materials Chemistry A 2017 vol. 5(Issue 17) pp:7876-7884
Publication Date(Web):2017/05/03
DOI:10.1039/C7TA00246G
Membranes with both high permeability and selectivity are desirable for practical separation. In this work, three hyperbranched polyesters (HPEs) with different numbers of hydroxyl-terminated groups and molecular structures were, respectively, incorporated into a polyamide film formed by the interfacial reaction between the mixtures of HPE/piperazine (PIP) and trimesoyl chloride (TMC) on PVC hollow fiber substrates to endow the corresponding thin film composite (TFC) membranes with different permselectivity performances. The successful incorporation of HPEs into the cross-linked polyamide matrix and their gradient distribution in the corresponding selective layer were confirmed by ATR-FTIR and XPS analyses. Moreover, the permeation experiments for the fabricated TFC membranes revealed that HPEs most likely existed within the network or/and aggregate pores of the polyamide matrix due to their nanometer sizes and flexible molecular structures. Both the changes in the pore structures and the increase in the hydrophilicity of the polyamide matrix with the introduction of abundant hydroxyl groups pending in the HPE molecules led to the permeate flux of the TFC membrane increasing significantly. Importantly, nearly spherical H40 HPEs with intramolecular cavities could act as a molecular sieve to endow the selective layer with a high rejection capability. Meanwhile, the H40/PIP selective layer with a more negatively charged surface exhibited a higher rejection for SO42− ions while maintaining a low rejection for Cl− ions. These findings encourage further exploration of a new alternative material with such structures like HPE by interfacial polymerization to construct an ultrathin barrier film with high permselectivity performance.
Co-reporter:Hong Zhang, Yin Zhang, Tiange Xu, Angelin Ebanezar John, Yang Li, Weishan Li, Baoku Zhu
Journal of Power Sources 2016 Volume 329() pp:8-16
Publication Date(Web):15 October 2016
DOI:10.1016/j.jpowsour.2016.08.036
•PMIA separators with a sponge-like structure are developed.•Excellent thermal stability and non-flammability contribute to higher safety.•Separators exhibit superior cell performances than commercial PP-based separators.A microporous poly(m-phenylene isophthalamide) (PMIA) separator with high safety (high-heat resistance and self extinguishing), high porosity and excellent liquid electrolyte wettability was prepared by the traditional nonsolvent introduced phase separation process. Due to the high-heat resistance of PMIA material, the as-prepared separator exhibited a negligible thermal shrank ratio at 160 °C for 1 h. Meanwhile, benefiting from its high porosity and excellent wettability in liquid electrolyte, the liquid electrolyte uptake and the ionic conductivity of the separator were higher than that of the commercial PP-based separators. Furthermore, the cell assembled with this separator showed better cycling performance and superior rate capacity compared to those with PP-based separators. These results suggested that the PMIA separator is very attractive for high-heat resistance and high-power density lithium-ion batteries.
Co-reporter:Hong Zhang, Yin Zhang, Zhikan Yao, Angelin Ebanezar John, Yang Li, Weishan Li, Baoku Zhu
Electrochimica Acta 2016 Volume 204() pp:176-182
Publication Date(Web):20 June 2016
DOI:10.1016/j.electacta.2016.03.189
•For the first time, a cross-linked gel polymer electrolyte with additional lithium ions, was introduced into a nonwoven separator.•The PI nonwoven is employed to ensure enhanced thermal stability and mechanical strength of the IACS.•With the introduction of PAMPS(Li+), the migration and mobility rate of anions could be hindered by the -SO3− group, giving rise to a high lithium ion transference number.•This IACS is recommended as a promising candidate for the high-power and high-safety lithium ion batteries.A novel composite nonwoven separator exhibiting high heat resistance, high ionic conductivity and high lithium ion transference number is fabricated by a simple dip-coating and heat treatment method. The thermal stable polyimide (PI) nonwoven matrix is chosen as a mechanical support and contributes to improving the thermal shrinkage of the composite nonwoven separator (abbreviated as IACS). The cross-linked poly(2-acrylamido-2-methylpropanesulfonic acid) PAMPS(Li+) gel polymer electrolyte (GPE), lithium ion sources of a single ion conductor, is introduced into the PI nonwoven matrix and acts as a functional filler. This PAMPS (Li+) GPE is proved to be able to provide internal short circuit protection, to alleviate liquid electrolyte leakage effectively, to supply more lithium ions dissociating from PAMPS (Li+) by liquid electrolyte solvent, to contribute a more stable interfacial resistance, and thus resulting in an excellent cyclability. More notably, the migration and mobility rate of anions could be hindered by the −SO3− group in the PAMPS (Li+) polymer based on electrostatic interaction, giving rise to a very high lithium ion transference number. These fascinating characteristics endow the IACS a great promise for the application in the high power and high safety lithium ion batteries.
Co-reporter:Hong Zhang, Chun-Er Lin, Ming-Yong Zhou, Angelin Ebanezar John, Bao-Ku Zhu
Electrochimica Acta 2016 Volume 187() pp:125-133
Publication Date(Web):1 January 2016
DOI:10.1016/j.electacta.2015.11.028
•For the first time, a sponge-like microporous PI separators were prepared via Soluble Precusor and Non-solvent Induced Phase Separation Process for Lithium Ion Batteries.•This PI separator with high porosity and pore-connectivity was successfully prepared by the incorporation of PEX.•This PI separator behaved high thermal stability and excellent electrochemical properties compared with the PP separator.Lithium ion battery separators with excellent thermal stability are highly desired to meet the requirements of electric vehicles. Basing on the excellent natures of PMDA-ODA polymide (PI) and processibility of the corresponding precursor solution of polyamic acid (PAA), the porous PI separators were prepared from the PAA precursor via non-solvent induced phase separation (NIPS) and thermal imidization process. By controlling the NIPS process, the ideal PI separator with high porosity and pore-connectivity was successfully obtained and employed in lithium ion batteries (LIBs). Besides the quite high thermal stability, this PI separator behaved excellent wettability in the liquid electrolyte and high liquid electrolyte uptake. By activated with liquid electrolyte, the ionic conductivity of the PI separator could reach as high as 2.15 mS·cm−1. Compared with the cells with the typical PP separators, the cells assembled with the PI separators performed the lower resistance, the higher discharge capacity and the better rate capability. These results suggested that the PAA-NIPS process could be an efficient and applicable route for preparing high performance PI separators.
Co-reporter:Hong Zhang, Ming-Yong Zhou, Chun-Er Lin and Bao-Ku Zhu
RSC Advances 2015 vol. 5(Issue 109) pp:89848-89860
Publication Date(Web):30 Sep 2015
DOI:10.1039/C5RA14087K
This study reviews the recent developments and the characteristics of polymeric separators used for lithium ion batteries. According to the structure and composition of the separators, they are broadly divided into four types: (1) polyolefin microporous separators, (2) heterochain polymer microporous separators, (3) polymer electrolytes and (4) non-woven separators. In particular, polymer electrolytes were defined as one category of separators for convenient description in this review; these feature intermediates between the two electrodes and possess transport properties comparable with the separator in liquid LIBs. For each category, the structure, characteristics, modification, and performance of separators are described. Finally, guidelines for further improvements in this research are outlined.
Co-reporter:Li-Feng Fang;Ming-Yong Zhou;Na-Chuan Wang;Li-Ping Zhu
Journal of Applied Polymer Science 2015 Volume 132( Issue 44) pp:
Publication Date(Web):
DOI:10.1002/app.42745
ABSTRACT
To improve the antifouling property of poly(vinyl chloride) (PVC) membranes, a series of poly(methacrylic acid) grafted PVC copolymers (PVC-g-PMAA) with different grafting degree were synthesized via one-step atom transfer radical polymerization process utilizing the labile chlorines on PVC backbones followed by one-step hydrolysis reaction. PVC/PVC-g-PMAA blend membranes with different grafting degree and copolymer content were prepared by nonsolvent induced phase separation method. The surface chemical composition, surface charge, membrane structures, wettability, permeability, separation performances and the fouling resistance of blend membranes were carefully investigated. The results indicated that the PMAA chains were segregated towards the surface and the membranes were endowed with negative charge. The hydrophilicity and permeability of the blend membranes were obviously improved. Furthermore, the antifouling ability especially at neutral or alkaline environments was also significantly increased. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42745.
Co-reporter:Li-feng Fang;Na-chuan Wang;Ming-yong Zhou
Chinese Journal of Polymer Science 2015 Volume 33( Issue 11) pp:1491-1502
Publication Date(Web):2015 November
DOI:10.1007/s10118-015-1701-4
To functionalize poly(vinyl chloride) (PVC) for various applications, monomers containing tertiary amine group are incorporated into PVC via atom transfer radical polymerization (ATRP) initiated by the labile chlorines in their backbones. The kinetics of synthesis was carefully investigated, and it is proven that the grafting polymerization process can be effectively controlled by regulating the reaction time. The membranes are fabricated using PVC and copolymers by non-solvent induced phase separation (NIPS) process. The hydrophilicity and pore structure of copolymer membranes were enhanced as well, these membranes are endowed with positive charge. When PDMA% (i.e., the PDMA weight percentage in copolymer) is 31.1%, the flux and Victoria blue B rejection are 26.0 L·m-2·h-1 (0.5 MPa) and 91.2%, respectively. Thus, the newly synthesized polymer is proven to be a promising material for dye separation with positive charges.
Co-reporter:Linghui Wang, Jun Wang, Xiaoying Gao, Zhiying Liang, Baoku Zhu, Liping Zhu and Youyi Xu
Polymer Chemistry 2014 vol. 5(Issue 8) pp:2836-2842
Publication Date(Web):06 Jan 2014
DOI:10.1039/C3PY01619F
A transetherification reaction between polysulfone (PSf) and poly(ethylene glycol) (PEG) alkoxide was proposed and explored for the preparation of polysulfone-poly(ethylene glycol) (PSf–PEG) amphiphilic block copolymers. The reaction efficiency and product structure were investigated by GPC, FTIR and 1H NMR. A bimolecular nucleophilic substitution mechanism (SN2) was proposed and verified by analyzing the linkage and terminal structures of the products. The molecular weight of copolymers determined by GPC was coincident with theoretical value. The mechanical properties of PSf–PEG were preserved by using HO–PEG–OH of high molecular weight. TGA and DSC were adopted to characterize the thermal properties of prepared copolymers. The good non-specific protein absorption resistance of PSf–PEG materials renders them desirable candidates for biomedical applications.
Co-reporter:Hao Li, Hong Zhang, Zhi-Ying Liang, Yue-Ming Chen, Bao-Ku Zhu, Li-Ping Zhu
Electrochimica Acta 2014 Volume 116() pp:413-420
Publication Date(Web):10 January 2014
DOI:10.1016/j.electacta.2013.11.076
•This work aims exploring microporous PVDF separators for lithium ion batteries.•Comb structure polymer PDMS-g-(PPO-PEO) was used in PVDF blend separators.•The influence of polyether side chains on interfacial resistance was studied.This work aims exploring the high performance porous separators that can be activated into gel electrolyte membranes for lithium ion batteries. A comb-like copolymer poly (dimethylsiloxane) graft poly (propylene oxide)-block-poly (ethylene oxide) (PDMS-g-(PPO-PEO)) was synthesized and blended with poly (vinylidene fluoride) (PVDF) to fabricate porous separators via a typical phase inversion process, and then the separators absorbed liquid electrolyte solution and formed into polymer electrolyte membranes. By measuring the composition, morphology and ion conductivity etc, the influence of PDMS-g-(PPO-PEO) on structure and properties of blend separators were discussed. Compared with pure PVDF separator with comparable porous structure, the adoption of PDMS-g-(PPO-PEO) decreased the crystallinity and increased the liquid electrolyte uptake and stability effectively. It was also found that the electrode/electrolyte interfacial resistance could be reduced greatly. The resulting electrolyte membrane using separator with PVDF/PDMS-g-(PPO-PEO) mass ratio in 8/2 exhibited highest ionic conductivity in 4.5 × 10−3 S/cm at room temperature, while the electrochemical stability was up to 4.7 V (vs. Li/Li+). Coin cells assembled with such separators also exhibited stable cycle performance and improved rate capabilities, especially when discharge rate higher than 0.5 C.
Co-reporter:Hao Li, Chun-Er Lin, Jun-Li Shi, Xiao-Ting Ma, Bao-Ku Zhu, Li-Ping Zhu
Electrochimica Acta 2014 Volume 115() pp:317-325
Publication Date(Web):1 January 2014
DOI:10.1016/j.electacta.2013.10.183
•PVDF/P(MMA-co-PEGMA) blend separators were prepared through NIPS method.•The stability mechanism of separator/liquid electrolyte system was analyzed.•Good cycling performances at different C-rates in C|GPE|LiFePO4 cellsMicroporous polymer separators and corresponding gel electrolyte have been widely used in lithium ion batteries. This work aims to explore a safety microporous separator for lithium ion batteries by studying the distribution and stability mechanism of liquid electrolyte in this kind of separator. A comb polymer P(MMA-co-PEGMA) was synthesized and blended into poly(vinylidene fluoride) (PVDF) matrix to prepare porous separators via immersion precipitation phase inversion process. The separators then were immersed in liquid electrolyte to form lithium ion conducting gel polymer electrolyte membranes (GPEs). The influence of P(MMA-co-PEGMA) on the morphology, crystallinity, and the liquid electrolyte uptake and distribution in the porous separators was investigated. The ion conductivity increased with copolymer content and the maximum conductivity value of 3.01 × 10−3 S cm−1 was found at 25 °C in the prepared samples. The Graphite|GPE|LiFePO4 cells assembled with modified separators showed improved capacity retention at various C-rates and higher coulombic efficiency than pure PVDF separators
Co-reporter:Hong Zhang, Xiaoting Ma, Chuner Lin and Baoku Zhu
RSC Advances 2014 vol. 4(Issue 64) pp:33713-33719
Publication Date(Web):17 Jul 2014
DOI:10.1039/C4RA04443F
This paper describes the preparation and properties of PVDF/P(hexafluorobutyl methacrylate-co-poly(ethyleneglycol)methacrylate)(P(HFBMA-co-PEGMA)) blend gel polymer electrolyte (GPE) for high-performance lithium-ion batteries. The fluorinated amphiphilic copolymer, P(HFBMA-co-PEGMA), was synthesized by simple radical polymerization and then blended into poly(vinylidene fluoride) (PVDF) matrix via immersion phase inversion process. The composition, morphologies, liquid electrolyte uptake of the blend membranes and electrochemical properties of the corresponding GPEs were systematically investigated. It is found that the introduction of P(HFBMA-co-PEGMA) results in a slight increase in porosity, a reduction in crystallinity and better affinity with liquid electrolyte, which consequently lead to a substantial increase in liquid electrolyte uptake and ion conductivity. For the membrane with P(HFBMA-co-PEGMA)/PVDF mass ratio in 1.7/10, the liquid electrolyte uptake and ionic conductivity reach to 387% and 3.19 mS cm−1, respectively. In addition, the resulting GPE is electrochemically stable up to about 4.5 V (vs. Li+/Li).
Co-reporter:Li-Feng Fang, Jun-Li Shi, Jin-Hong Jiang, Hao Li, Bao-Ku Zhu and Li-Ping Zhu
RSC Advances 2014 vol. 4(Issue 43) pp:22501-22508
Publication Date(Web):29 Apr 2014
DOI:10.1039/C4RA01713G
This study aims to improve the wettability and thermal resistance of polypropylene (PP) separators for lithium ion batteries. The PP separator was first coated with polydopamine (PDA) on the basis of mussel-inspired surface chemistry. Then a thin inorganic–organic hybrid layer was immobilized onto the PDA-coated separator via a sol–gel process using tetraethoxysilane (TEOS) solutions. This method does not need any commonly-used polymeric binders because of the unique adhesion behaviour of the PDA intermediate layer, which greatly reduces the thickness of the modification layer and avoids excessive pore blocking. Owing to the incorporation of the hybrid layer, the composite separators showed better affinity with the liquid electrolyte and obvious reduction in thermal shrinkage in comparison to the unmodified separator. And the battery performances, such as interfacial resistance, discharge capacity and C-capacity were all improved after modification. Considering the effective adhesion of PDA onto nearly all kinds of separator/membrane surfaces, this modification strategy can be widely used without causing any obvious damage to the mechanical strength of the unmodified separators/membranes.
Co-reporter:Linghui Wang, Yue Cui, Nachuan Wang, Hong Zhang, Baoku Zhu, Liping Zhu, Youyi Xu
Polymer Degradation and Stability 2014 Volume 103() pp:69-74
Publication Date(Web):May 2014
DOI:10.1016/j.polymdegradstab.2014.03.013
Aminolysis reaction between polyarylsulfones and organic amines was investigated. A bimolecular nucleophilic substitution mechanism was proposed. The nucleophilic reagent attacks the aryl ether bond carbon on the aryl ring carrying substituents with strong electron-attracting character. 1H NMR and 1H–1H COSY NMR spectroscopies were adopted to characterize the chemical structure of the products, the terminal groups especially. The effect of polyarylsulfone structure on the reactivity was studied by comparing the reaction rates. The aminolysis kinetics of polyethersulfone with ethylenediamine at different temperature and reagent concentration was studied in detail. The molar mass of the aminolyzed product was determined by GPC and theoretical deduction, and they showed great consistency.
Co-reporter:Li-Feng Fang;Jun-Li Shi;Hao Li;Li-Ping Zhu
Journal of Applied Polymer Science 2014 Volume 131( Issue 21) pp:
Publication Date(Web):
DOI:10.1002/app.41036
ABSTRACT
To effectively improve the affinity of polyethylene (PE) separators with liquid electrolyte without causing a serious pore blockage and to develop a more suitable technology for the industrial production process, porous polyvinylidene fluoride (PVDF) layer-coated PE separators are prepared by the dip-coating method followed by a dry-cast process. Different from previous investigations, a less volatile solvent and a relatively volatile nonsolvent are used to yield a preferable pore structure. A brief introduction on the pore formation mechanism during the dry-cast process is provided. The pore structure of coating layer is found to be successfully controlled by changing evaporation temperature, nonsolvent content, and PVDF concentration. The porous PVDF coating layer-modified separators show better affinity with liquid electrolyte and thermal stability. Especially, the ionic conductivity of the modified separator/liquid electrolyte system with a suitable porous coating layer on the separator could reach two times as that of PE separator/liquid electrolyte system, and the cell assembled with modified PE separator shows better cycle performances. This modification process is proved to be a facile, controllable, and effective method for PE separator modification. Meanwhile, this work could provide some theoretical and technical guidance for the production process. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41036.
Co-reporter:Jian-hua Wang;Yong-hua Zhang;You-yi Xu
Chinese Journal of Polymer Science 2014 Volume 32( Issue 2) pp:143-150
Publication Date(Web):2014 February
DOI:10.1007/s10118-014-1371-7
Porous PVDF blend membranes with good hydrophilicity and a symmetric structure were prepared by the phase inversion method using amphiphilic brush-like copolymers, P(MMA-r-PEGMA), as hydrophilic additive and triethylphosphate (TEP) as solvent. P(MMA-r-PEGMA) was synthesized by radical polymerization in TEP. Then the obtained amphiphilic copolymer solution was mixed with PVDF and TEP to prepare the dope solution. The effects of P(MMA-r-PEGMA) content and coagulation composition on membrane morphologies were investigated using scanning electron microscopy (SEM). The results demonstrated that, even blended with amphiphilic copolymers, a symmetric structure can be formed. Hollow fiber membranes with a mainly symmetric structure were also fabricated. The dry hollow fiber membranes showed good hydrophilicity, high flux and good rejection performance because of their hydrophilic surface and pores wall.
Co-reporter:Jian-hua Wang;Yue-li Wu;Yong-hua Zhang
Chinese Journal of Polymer Science 2014 Volume 32( Issue 3) pp:377-384
Publication Date(Web):2014 March
DOI:10.1007/s10118-014-1374-4
A low operating pressure nanofiltration membrane is prepared by interfacial polymerization between m-phenylenediamine (MPDA) and trimesoyl chloride (TMC) using PVC hollow fiber membrane as supporting. A series of PVC nanofiltration membranes with different molecular weight cutoff (MWCO) can be obtained by controlling preparation conditions. Chemical and morphological characterization of the membrane surface was carried out by FTIR-ATR and SEM. MWCO was characterized by filtration experiments. The preparation conditions were investigated in detail. At the optimized conditions (40 min air-dried time, aqueous phase containing 0.5% MPDA, 0.05% SDS and 0.6% acid absorbent, oil phase containing 0.3% TMC, and 1 min reaction time), under 0.3 MPa, water flux of the gained nanofiltration membrane reaches 17.8 L/m2·h, and the rejection rates of methyl orange and MgSO4 are more than 90% and 60%, respectively.
Co-reporter:Jun-Li Shi, Li-Feng Fang, Hao Li, Hong Zhang, Bao-Ku Zhu, Li-Ping Zhu
Journal of Membrane Science 2013 Volume 437() pp:160-168
Publication Date(Web):15 June 2013
DOI:10.1016/j.memsci.2013.03.006
► PMMA was immobilized onto PE separator skeleton to form “active separator”.► Separator was modified via surface-initiated ATRP based on dopamine pretreatment.► The proportion of the gel part was quantitatively estimated.► The ionic conductivity was up to 1.19×10−3 S.cm−1 at 25 °C.► Separators showed improved thermal stability and electrochemical performances.In this work, PMMA layer was immobilized onto PE separator skeleton via surface-initiated ATRP based on dopamine pretreatment. The incorporated “active” layer made separator matrix could be swollen by electrolyte solution to some extent and show some properties of gel polymer electrolyte. Resulted separators were characterized by ATR-FTIR, SEM, contact angle and electrochemical methods. The prepared separators showed improved thermal stability. The electrolyte uptake and ionic conductivity were also elevated due to the improved affinity between separator and liquid electrolyte. The room temperature ion conductivity reached up to 1.19×10−3 S cm−1. The stability of liquid electrolyte trapped in the separator was enhanced obviously. Cells assembled with such “active separators” showed better cycle performances. These results primarily showed that it was a promising way to prepare high performance PE based separators for lithium ion batteries.
Co-reporter:Jun-Li Shi;Li-Feng Fang;Hong Zhang;Zhi-Ying Liang, ;Li-Ping Zhu
Journal of Applied Polymer Science 2013 Volume 130( Issue 4) pp:2680-2687
Publication Date(Web):
DOI:10.1002/app.39491
ABSTRACT
Blending the block copolymer into the membrane matrix is a convenient and efficient way for membrane modification. In this study, HDPE/PE-b-PEG membranes were prepared via TIPS process, and the extractant effect was investigated. An interesting finding was that a non-polar extractant (n-hexane) was more conducive to the surface enrichment of PEG chains than a polar solvent (ethanol). The reason was deemed to be the combined effect of entropy drive, interfacial energy, and the swelling behavior. Besides, membrane performances related to the surface chemical properties were studied. Results suggested that the prepared blend membranes extracted by n-hexane showed enhanced hydrophilicity, anti-fouling property and water flux. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2680–2687, 2013
Co-reporter:Jun-Li Shi;Li-Feng Fang;Hong Zhang;Zhi-Ying Liang;Li-Ping Zhu
Journal of Applied Polymer Science 2013 Volume 130( Issue 5) pp:3816-3824
Publication Date(Web):
DOI:10.1002/app.39416
ABSTRACT
The blending of a block copolymer into the membrane matrix is a convenient and efficient way to modify membranes. In this study, high-density polyethylene/polyethylene-b-poly(ethylene glycol) (PEG) membranes were prepared via a thermally induced phase separation process, and the extractant effect was investigated. An interesting finding was that the nonpolar extractant (n-hexane) was more conducive to the surface enrichment of the PEG chains than the polar solvent (ethanol). The reason was deemed to be the combined effect of the entropy drive, interfacial energy, and swelling behavior. In addition, the membrane performance related to the surface chemical properties was studied. The results suggest that the prepared blend membranes extracted by n-hexane showed enhanced the hydrophilicity, antifouling properties, and water flux. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3816–3824, 2013
Co-reporter:Jun-li Shi;Hao Li;Li-feng Fang;Zhi-ying Liang
Chinese Journal of Polymer Science 2013 Volume 31( Issue 2) pp:309-317
Publication Date(Web):2013 February
DOI:10.1007/s10118-013-1222-y
To improve the performances of HDPE-based separators, polyether chains were incorporated into HDPE membranes by blending with poly(ethylene-block-ethylene glycol) (PE-b-PEG) via thermally induced phase separation (TIPS) process. By measuring the composition, morphology, crystallinity, ion conductivity, etc, the influence of PE-b-PEG on structures and properties of the blend separator were investigated. It was found that the incorporated PEG chains yielded higher surface energy for HDPE separator and improved affinity to liquid electrolyte. Thus, the stability of liquid electrolyte trapped in separator was increased while the interfacial resistance between separator and electrode was reduced effectively. The ionic conductivity of liquid electrolyte soaked separator could reach 1.28 × 10−3 S·cm−1 at 25°C, and the electrochemical stability window was up to 4.5 V (versus Li+/Li). These results revealed that blending PE-b-PEG into porous HDPE membranes could efficiently improve the performances of PE separators for lithium batteries.
Co-reporter:Jun-Li Shi, Li-Feng Fang, Hao Li, Zhi-Ying Liang, Bao-Ku Zhu, Li-Ping Zhu
Journal of Membrane Science 2013 429() pp: 355-363
Publication Date(Web):
DOI:10.1016/j.memsci.2012.11.055
Co-reporter:Li-Feng Fang, Jun-Li Shi, Bao-Ku Zhu, Li-Ping Zhu
Journal of Membrane Science 2013 448() pp: 143-150
Publication Date(Web):
DOI:10.1016/j.memsci.2013.07.065
Co-reporter:Wei-dong Liu;Yong-hua Zhang;Li-feng Fang
Chinese Journal of Polymer Science 2012 Volume 30( Issue 4) pp:568-577
Publication Date(Web):2012 July
DOI:10.1007/s10118-012-1153-z
Three well-defined diblock copolymers of poly(methyl methacrylate-b-methacrylic acid) (P(MMA-b-MAA)) were synthesized using atom transfer radical polymerization method and varying poly(methacrylic acid) (PMAA) chain lengths. These copolymers were blended with PVC to fabricate porous membranes via phase inversion process. Membrane morphologies were observed by scanning electron microscopy (SEM), and chemical composition changes of the membrane surfaces were measured by X-ray photoelectron spectroscopy (XPS). Static and dynamic protein adsorption experiments were used to evaluate antifouling properties of the blend membranes. It was found that, the blend membranes containing longer PMAA arm length showed lower static protein adsorption, higher water permeation flux and better protein solution flux recovery.
Co-reporter:Hao Li, Xiao-Ting Ma, Jun-Li Shi, Zhi-Kan Yao, Bao-Ku Zhu, Li-Ping Zhu
Electrochimica Acta 2011 Volume 56(Issue 6) pp:2641-2647
Publication Date(Web):15 February 2011
DOI:10.1016/j.electacta.2010.12.010
Poly(ethylene oxide) (PEO) filled polypropylene separators (GFPSs) are designed by means of thermal cross-linking of entrapped poly(ethylene glycol) methyl ether acrylate (PEGMEA) and poly(ethylene glycol) diacrylate (PEGDA) as gel constituents. The intrinsic properties of GFPS and their corresponding gel polymer electrolytes (GPE) are characterized by DSC, SEM, contact angle and electrochemical methods. It is found the stability of liquid electrolyte uptake in GPE could be improved obviously. For the GPE prepared from GFPS with filled polyether content of 14.3 wt%, the ionic conductivity could reach 1.12 × 10−3 S cm−1 while the electrochemically stable window reach 5.0 V (vs. Li/Li+). These primary results show great promise of this simple method to prepare GPE for practical application in lithium ion batteries.
Co-reporter:Dong-Xu Pang;Wei-Dong Liu;Tong Li;Li-Feng Fang
Journal of Applied Polymer Science 2011 Volume 119( Issue 5) pp:2953-2960
Publication Date(Web):
DOI:10.1002/app.33014
Abstract
The new amphiphilic triblock copolymers of poly(N-vinyl pyrrolidone-b-methyl methacrylate-b-N-vinyl pyrrolidone) (P(VP-b-MMA-b-VP)) were synthesized via a reversible addition fragmentation chain transfer polymerization route. Using these copolymers as additives in casting solutions, the porous blend membranes of poly (vinylidene fluoride) and P(VP-b-MMA-b-VP) were prepared following a typical nonsolvent induced phase separation process. The influences of P(VP-b-MMA-b-VP) on the morphologies of the blend membranes were observed by scanning electron microscopy. The chemical compositions in membrane surface layers were measured by X-ray photoelectron measurement. Water contact angle and water flux experiments were used to evaluate the hydrophilicity and permeation properties of the blend membranes. It was found that the P(VP-b-MMA-b-VP) copolymers could be retained in membrane stably in membrane formation and application process. The copolymers could enrich in surface layer and endowed the blend membrane with efficient hydrophilicity and higher water permeation flux. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Co-reporter:Hao Li, Yue-Ming Chen, Xiao-Ting Ma, Jun-Li Shi, Bao-Ku Zhu, Li-Ping Zhu
Journal of Membrane Science 2011 379(1–2) pp: 397-402
Publication Date(Web):
DOI:10.1016/j.memsci.2011.06.008
Co-reporter:Yong-Hong Zhao;You-Yi Xu
Journal of Applied Polymer Science 2010 Volume 117( Issue 1) pp:548-556
Publication Date(Web):
DOI:10.1002/app.30993
Abstract
Porous membranes were prepared via phase inversion process from casting solutions composed of poly(vinylidene fluoride), hyperbranched polyglycerol (HPG), and N,N-dimethylacetamide. To seek a stable presence of HPG in the resulting membranes, it was crosslinked in the casting solutions using 4,4′-oxydiphthalic anhydride as the crosslinking agent. The membranes were characterized in terms of morphology, surface and bulk chemical compositions, water contact angle, porosity, water flux, and bovine serum albumin (BSA) adsorption experiments. The effects of HPG content and crosslinking degree on the membrane structure and properties were investigated. The increasing of crosslinking degree resulted in a significant improvement in HPG stability in the membrane matrix, and a remarkable enrichment of the crosslinked HPG at the separation surface was observed when the membrane was shaken in water at a relatively high temperature (60°C). This enrichment led to a decrease in the value of water contact angle and an improvement in fouling-resistance. To optimize the membrane performance, a small amount of poly(vinylpyrrolidone) (PVP) was used as an additive, and it was found that the addition of PVP led to a considerable increase in water flux. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Co-reporter:Mei Zhang;Chun-fang Zhang;Zhi-kan Yao;Jun-li Shi
Chinese Journal of Polymer Science 2010 Volume 28( Issue 3) pp:337-346
Publication Date(Web):2010 May
DOI:10.1007/s10118-010-9022-0
High density polyethylene (HDPE)/polyethylene-block-poly(ethylene glycol) (PE-b-PEG) blend porous membranes were prepared via thermally induced phase separation (TIPS) process using diphenyl ether (DPE) as diluent. The phase diagrams of HDPE/PE-b-PEG/DPE systems were determined by optical microscopy and differential scanning calorimetry (DSC). By varying the content of PE-b-PEG, the effects of PE-b-PEG copolymer on morphology and crystalline structure of membranes were studied by scanning electron microscopy (SEM) and wide angle X-ray diffraction (WAXD). The chemical compositions of whole membranes and surface layers were characterized by elementary analysis, Fourier transform infrared spectroscopy-attenuated total reflection (FTIR-ATR) and X-ray photoelectron spectroscopy (XPS). Water contact angle, static protein adsorption and water flux experiments were used to evaluate the hydrophilicity, antifouling and water permeation properties of the membranes. It was found that the addition of PE-b-PEG increased the pore size of the obtained blend membranes. In the investigated range of PE-b-PEG content, the PEG blocks could not aggregate into obviously separated domains in membrane matrix. More importantly, PE-b-PEG could not only be retained stably in the membrane matrix during membrane formation, but also enrich at the membrane surface layer. Such stability and surface enrichment of PE-b-PEG endowed the blend membranes with improved hydrophilicity, protein absorption resistance and water permeation properties, which would be substantially beneficial to HDPE membranes for water treatment application.
Co-reporter:Yong-Hong Zhao, You-Yi Xu, Bao-Ku Zhu
Solid State Ionics 2009 Volume 180(32–35) pp:1517-1524
Publication Date(Web):26 November 2009
DOI:10.1016/j.ssi.2009.10.003
An amphiphilic hyperbranched-star polymer (HPE-g-MPEG) was synthesized by grafting methoxy poly(ethylene glycol) to the end of the hyperbranched polyester (HPE) molecule using terephthaloyl chloride (TPC) as the coupling agent. The synthesized amphiphilic hyperbranched-star polymer was blended with poly(vinylidene fluoride) (PVDF) to fabricate porous membranes via typical phase inversion process, and then the membranes were filled and swollen by a liquid electrolyte solution to form polymer electrolytes. The influences of HPE-g-MPEG on the morphology, crystallinity, liquid electrolyte uptake, mechanical properties of the porous membranes and the electrochemical properties of the activated membranes were investigated. It was found that the addition of HPE-g-MPEG resulted in a significant increase in porosity and a considerable reduction in crystallinity of the blend membranes, which favored the liquid electrolyte uptake and, consequently, led to a remarkable increase in ion conductivity at ambient temperature. The maximum ion conductivity observed in this study was 1.76 × 10− 3 S/cm at 20 °C for the blend membrane with a HPE-g-MPEG/PVDF ratio of 3/10 (w/w).
Co-reporter:Xiu-Zhen Wei, Xiao-Fen Liu, Li-Ping Zhu, Bao-Ku Zhu, Yan-Fei Wei, You-Yi Xu
Journal of Membrane Science 2008 Volume 307(Issue 2) pp:292-298
Publication Date(Web):15 January 2008
DOI:10.1016/j.memsci.2007.09.046
Crosslinked hyperbranched poly(amine-ester) (HPAE) membranes were prepared by crosslinking its terminal hydroxyl groups with glutaraldehyde (GA). The crosslinked HPAE membranes showed high reactivity and good hydrophilicity. The crosslinking degree was investigated by Fourier transformation infrared spectra (FT-IR). Atom force microscope (AFM) and scanning electron microscope (SEM) reveals that the crosslinked HPAE films have smooth surfaces, dense and homogenous matrices. The swelling degree of the membrane was higher in water than that in isopropanol. From the permeation of pure water through the HPAE membrane, the effect of hydroxyl/aldehyde group ratio on the permeation flux and separation factor was investigated. The results indicated that the permeation flux increase was accompanied with the separation factor decrease if the water concentration increased in the feed solution.
Co-reporter:Mei Zhang, Ai-Qing Zhang, Bao-Ku Zhu, Chun-Hui Du, You-Yi Xu
Journal of Membrane Science 2008 Volume 319(1–2) pp:169-175
Publication Date(Web):1 July 2008
DOI:10.1016/j.memsci.2008.03.029
Porous poly(vinylidene fluoride) (PVDF) membranes were prepared via immersion precipitation process from PVDF/dimethyl sulfoxide (DMSO)/water system. By manipulating precipitation temperature and PVDF concentration in casting solution, the polymorphism in the formed porous membranes was studied. Membrane morphologies were observed by field emission scanning electron microscopy (FESEM) and thermal behaviors of membranes were examined by differential scanning calorimetry (DSC). Wide angle X-ray diffraction (WAXD) and Fourier transform infrared spectroscopy-attenuated total reflection (FTIR-ATR) were employed to analyze the crystalline structures of the overall membranes and the surface layers. It was found that, for all the investigated cases, PVDF mainly crystallized into the α form crystalline structure in the overall membrane, while the α and β phases coexisted in the surface layers. The total crystallinity of the membrane and the β/α phase ratio in the surface layers increased simultaneously while raising PVDF concentration in casting solution or reducing precipitation temperature.
Co-reporter:Zhen-Yu Cui;Chun-Hui Du;You-Yi Xu;Gen-Liang Ji
Journal of Applied Polymer Science 2008 Volume 108( Issue 1) pp:272-280
Publication Date(Web):
DOI:10.1002/app.27494
Abstract
Sulfolane was acted as a kind of diluent to prepared PVdF porous membranes via TIPS process. Its impact on structure and morphology was studied. Phase diagram for this system was determined by different scanning calorimetry (DSC). Not any structure in the region higher than the dynamic crystallization temperature can be found and the temperature at which particle formation was observed by the optical microscope was approximately in agreement with the dynamic crystallization temperature, which revealed that only S–L phase separation happened for PVdF/sulfolane system during TIPS process. It was found that the heat of crystallization increased with the increase of polymer content. The increase of the cooling rate will increase the crystallization rate. SEM, which showed that membranes had symmetrical structure and pores formed between PVdF crystallization, revealed that PVdF will present different crystallization morphology as the cooling rate changed. With the cooling rate decrease, both the size of particles and the channel size of open pores between particles became larger, but more uneven. As the cooling rate increased, the size of particles decreased and pore became well interconnected and uniform, which were confirmed by the measurement of average pore size and pore size distribution. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Co-reporter:Xiu-Zhen Wei;Li-Ping Zhu;You-Yi Xu
Journal of Applied Polymer Science 2008 Volume 109( Issue 6) pp:3613-3621
Publication Date(Web):
DOI:10.1002/app.28383
Abstract
Novel films based on hydroxyl terminated hyperbranched poly (amine-ester) (HPAE-OH) of different generation were prepared by crosslinking the terminal hydroxyl groups of HPAE with glutaraldehyde (GA). The progress of crosslinking reaction was characterized by Fourier transform infrared (FTIR) and viscosity measurement. The surface morphology of the crosslinked HPAE films was characterized by field emission scanning electron microscope (FE-SEM) and atomic force microscopy. The results suggested that the films have homogenously dense interior matrices and smooth surface. The hydrophilicity/hydrophobicity of the crosslinked HPAE films was characterized by the water contact angle measurement. Variable swelling behavior in different solvents was also studied. The in vitro biocompatibility of the film was investigated by the bovine hemoglobin (Hb) adsorption measurement. And these results showed that these crosslinked HPAE films had excellent hydrophilicity, variable swelling behavior in different solvents, and relative low protein absorption. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Co-reporter:Yanling Qian;Jianhua Wang;Baoku Zhu;Mei Zhang
Frontiers of Chemistry in China 2008 Volume 3( Issue 4) pp:432-439
Publication Date(Web):2008 December
DOI:10.1007/s11458-008-0078-0
Amphiphilic comb-like polysiloxane (ACPS) containing polyether side chains was used as the modification reagent in the preparation of hydrophilic porous poly (vinylidene fluoride) (PVDF) membranes via a phase inversion process. The effects of ACPS on morphology, crystallinity, mechanical properties, reservation of ACPS in the phase inversion process, chemical structure, hydrophilicity and filterability performance of porous PVDF membranes were discussed. It was found that the addition of ACPS would result in the delayed demixing which yields “sponge-like” sublayers and longer crystallization time during the membrane formation process. It was revealed that O/F ratios of the bulk membrane were almost the same as those of the corresponding casting solutions which obviously indicated the high reservation of ACPS in the membrane formation process. The fact that the O/F ratios in the membrane surface layers were much higher than those in the bulk membrane proved the enrichment of ACPS on the surface. The filterability experiments and water contact angle testing proved the hydrophilicity of the blend membranes. Through a schematic model, the mechanism relating the membrane structure and performance was interpreted. From the observed results, it can be concluded that ACPS acts as a potential candidate material for preparing PVDF membranes with extraordinary hydrophilicity and filterability.
Co-reporter:Mei Zhang;Aiqing Zhang;Zhenyu Cui
Frontiers of Chemical Science and Engineering 2008 Volume 2( Issue 1) pp:89-94
Publication Date(Web):2008 March
DOI:10.1007/s11705-008-0011-6
Lithium ion conducting membranes are the key materials for lithium batteries. The lithium ion conducting gel polymer electrolyte membrane (Li-GPEM) based on porous poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) matrix and cross-linked PEG network is prepared by a typical phase inversion process. By immersing the porous PVDF-HFPmembrane in liquid electrolyte containing poly(ethylene glycol) diacrylate (PEGDA) and an initiator to absorb the liquid electrolyte at 25°C, and then thermally cross-linking at 60°C, the Li-GPEMis fabricated successfully. The measurements on its weight loss, mechanical and electrochemical properties reveal that the obtained Li-GPEM has better overall performance than the liquid and blend gel systems used as conductive media in lithium batteries. The ionic conductivity of the fabricated Li-GPEM can reach as high as 2.25 × 10−3 S/cm at 25°C.
Co-reporter:Yong-Hong Zhao, Yan-Ling Qian, Dong-Xu Pang, Bao-Ku Zhu, You-Yi Xu
Journal of Membrane Science 2007 Volume 304(1–2) pp:138-147
Publication Date(Web):1 November 2007
DOI:10.1016/j.memsci.2007.07.029
Amphiphilic hyperbranched-star polymers (HPE-g -MPEG) with different arm length were synthesized by grafting methoxy poly(ethylene glycol)s (MPEGs, M¯n=350,750 and 2000, respectively) to the hyperbranched polyester (HPE) molecule using terephthaloyl chloride (TPC) as the coupling agent, and blended with PVDF to fabricate porous membranes via phase inversion process. Membrane morphologies were observed by scanning electron microscopy (SEM) and atomic force microscope (AFM), and chemical composition changes of the membrane surfaces were measured by X-ray photoelectron spectroscopy (XPS). Water contact angle, static protein adsorption, and filtration experiments were used to evaluate the hydrophilicity and anti-fouling properties of the membranes. It was found that, with the increase in MPEG arm length, the MPEG segments of HPE-g-MPEG enriched at the membrane surfaces substantially, resulting in a significant decrease in water contact angle. Furthermore, the blend membranes containing longer arm HPE-g-MPEGs showed lower static protein adsorption, higher protein solution fluxes, and better protein solution flux recovery than the pure PVDF membrane.
Co-reporter:Chun-Hui Du;You-Yi Xu
Journal of Applied Polymer Science 2007 Volume 106(Issue 3) pp:1793-1799
Publication Date(Web):17 JUL 2007
DOI:10.1002/app.26867
Melt-spinning and stretching (MS-S) method was proposed for preparing poly(vinylidene fluoride) (PVDF) hollow fiber membranes with excellent mechanical properties. The morphology and properties of PVDF fibers and membranes were investigated by small angle X-ray scattering (SAXS), differential scanning calorimeter (DSC), field emission scanning electron microscope, mercury porosimeter, and tensile experiment. SAXS results indicated that the stacked lamellar structure aligned normal to the fiber axis was separated and deformed when the fibers were strained, and the long period of the strained fibers increased accordingly. Factors affecting the membrane properties were mainly spin-draw ratio, annealing temperature, time, and stretching rate. Experimental results showed that the average pore size, porosity, and N2 permeation of the membranes all increased with the increasing spin-draw ratios and annealing temperatures. Annealing the nascent PVDF hollow fibers at 145°C for 12 h was suitable for attaining membranes with good performance. In addition, the amount and size of the micropores of the membrane increased obviously with stretching rate. Tensile experiment indicated PVDF hollow fiber membranes made by MS-S process had excellent mechanical properties. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Co-reporter:Bao-Ku Zhu;Jian Zhang;Wei-Dong Liu;You-Yi Xu
Polymers for Advanced Technologies 2007 Volume 18(Issue 7) pp:522-528
Publication Date(Web):12 MAR 2007
DOI:10.1002/pat.910
Using poly(amic acid) (PAA) as a precursor followed by thermal imidization, the polyimide/silica nanocomposite films were prepared via an improved sol–gel process and a blending process, respectively. FT-IR, TEM and TGA measurements were used to characterize the structure and properties of the obtained films. The results confirmed that the introduction of silica did not yield negative effects on the conversion of the PAA precursor to the polyimide. With the increase of silica content, the aggregation of silica appeared in the polyimide matrix, and the thermal stability decreased slightly for both kinds of films. The dielectric constant (ε) of both films increased slowly with the increase of the silica concentration. The dielectric constant of the obtained polyimide/silica nanocomposite films displayed good stability within a wide range of temperatures or frequency. Based on modeling relation between ε and silica content, the difference in dielectric properties for two kinds of nanocomposites are discussed. Copyright © 2007 John Wiley & Sons, Ltd.
Co-reporter:Ling Xiao;Xiuzhen Wei;Baoku Zhu
Frontiers of Chemical Science and Engineering 2007 Volume 1( Issue 4) pp:355-359
Publication Date(Web):2007 October
DOI:10.1007/s11705-007-0064-y
Basing on hydroxyl terminated hyperbranched poly(amine-ester)s (HPAEs), the cross-linking reactions and preparation of ester-crosslinked HPAE films were investigated using succine anhydride (SA) as crosslink reagent. It was proved that the cross-linking reaction between HPAE and SA followed a two-step mechanism. This mechanism provides an efficient route to prepare HPAE/SA cross-linked films, in which, the precursor films were prepared by casting HPAE/SA solution at a lower temperature, and then curing the films at a higher temperature. By varying SA content, the solid HPAE/SA films with different cross-linking degrees were prepared successfully. The highest tensile strength of the cross-linked film could reach 59.60 MPa. With all water contact angle smaller than 74.3°, the crosslinked films demonstrated good hydrophilic properties.
Co-reporter:Hui-Juan Chu;You-Yi Xu
Journal of Applied Polymer Science 2006 Volume 102(Issue 2) pp:1734-1740
Publication Date(Web):28 JUL 2006
DOI:10.1002/app.24364
To explore ultralow dielectric constant polyimide, the crosslinked polyimide foams (PIFs) were prepared from 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA), 4,4′-oxydianiline (ODA), and 2,4,6-triaminopyrimidine (TAP) via a poly(ester–amine salt) (PEAS) process. FTIR measurements indicated that TAP did not yield a negative effect on imidization of PEAS precursors. SEM measurement revealed the homogeneous cell structure. Through using TAP as a crosslinking monomer, the mechanical properties of PIFs could be improved in comparison with uncrosslinked BTDA/ODA based PIF. The crosslinked PIFs still exhibited excellent thermal stability with 5% weight loss temperatures higher than 520°C. In the field with frequency higher than 100 Hz, the dielectric constants of the obtained PIFs ranged from 1.77 to 2.4, and the dielectric losses were smaller than 3 × 10−2 at 25–150°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1734–1740, 2006
Co-reporter:Hui-Juan Chu;You-Yi Xu
Polymers for Advanced Technologies 2006 Volume 17(Issue 5) pp:366-371
Publication Date(Web):22 MAY 2006
DOI:10.1002/pat.719
In order to obtain cellular materials with low dielectric properties, crosslinked polyimide foams were prepared using 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA), 4,4′-oxydianiline (ODA) and 2,4,6-triaminopyrimidine (TAP) as monomer via a poly(ester-amine salt) precursor process. The structures of the precursors and the polyimide foams were characterized by thermogravimetric analysis (TGA) and FT-IR, while the morphologies of the polyimide foams were viewed from scanning electron microscopy (SEM) measurements. The results revealed that the poly(ester-amine salt) precursor containing TAP could successfully be converted to a crosslinked polyimide foam with relatively uniform cell structure. Also, the crosslinking of TAP improved the mechanical properties of foams in comparison with the non-crosslinking systems. With increasing content of TAP, the dielectric constants of the polyimide foams decreased gradually. For the foam with TAP molar ratio at 15%, the dielectric constant was as low as 1.77 at the frequency of 10 kHz. Though the thermal resistance decreased slightly for crosslinked foams, the decomposition temperatures were still maintained above 520°C. Copyright © 2006 John Wiley & Sons, Ltd.
Co-reporter:Bao-Ku Zhu;Xiu-Zhen Wei;Ling Xiao;You-Yi Xu;Kurt E Geckeler
Polymer International 2006 Volume 55(Issue 1) pp:
Publication Date(Web):9 NOV 2005
DOI:10.1002/pi.1919
Novel films based on cross-linked hyperbranched poly(amine-ester) (HPAE) were prepared by cross-linking the terminal hydroxyl groups of HPAE using glutaraldehyde (GA). The cross-linking process was monitored by measuring the intrinsic viscosity of HPAE/GA in N,N-dimethylacetamide. The surface structures of the cross-linked HPAE films obtained from different HPAE/GA ratios were imaged using atom force microscopy, and their properties were characterized in terms of hydrophilicity, solvent swelling, mechanics, and protein adsorption. It was found that the static contact angle was <32.9°, tensile strength was >0.35 MPa, elongation at break was >9.2%, swelling degree was >63% in water, and bovine serum albumin adsorption was relatively low. The results indicate that cross-linked HPAE films have a strong application potential in many areas. Copyright © 2005 Society of Chemical Industry
Co-reporter:Bao-Ku Zhu;Xiu-Zhen Wei;Kurt E. Geckeler;You-Yi Xu;Ling Xiao;Xiu-Zhen Wei;Ling Xiao;You-Yi Xu;Kurt E. Geckeler
Macromolecular Rapid Communications 2005 Volume 26(Issue 15) pp:1224-1227
Publication Date(Web):29 JUL 2005
DOI:10.1002/marc.200500242
Summary: Novel hyperbranched poly(amine-ester) (HPAE) cross-linked films were prepared by cross-linking the terminal hydroxyl groups of HPAE using glutaraldehyde (GA). Atom force microscope and scanning electron microscope revealed their smooth surfaces, dense and homogenous matrices. Property characterizations indicated that these cross-linked films had good hydrophilicity, relative low protein adsorption, and high tensile strength. Also, their swelling behavior varied with the solvent.
Co-reporter:Shu-Hui Xie, Bao-Ku Zhu, Zhi-Kang Xu, You-Yi Xu
Materials Letters 2005 Volume 59(19–20) pp:2403-2407
Publication Date(Web):August 2005
DOI:10.1016/j.matlet.2005.03.024
To develop the polymer-based materials with high dielectric constant and thermal stability, Li and Ti doped NiO (LTNO) particles with super high dielectric constant (ε) were dispersed into pyromellitic dianhydride (PMDA) and 4, 4′-oxydianiline (ODA)-based polyimide. Through mixing LTNO particles with the poly(amic acid) precursor solution, casting film and following thermal curing, the polyimide/LTNO composite films were obtained. The thermal stability and structure of the composites were studied by TGA and X-ray diffraction, respectively. Dielectric and conductive measurements were adopted to investigate the properties of the samples. The results revealed that the obtained composites had good morphology stability, but their thermal resistances become a little lower in comparison with pure polyimide. With increasing the content of LTNO particles, ε and conductivity of the composite films increased greatly. For the sample with the LTNO content at 0.4 in volume fraction, ε was as high as 570 at the frequency of 100 Hz. It showed that doping LTNO particles into polyimide would be an efficient route to high ε composites.
Co-reporter:Jian Zhang;Hui-Juan Chu;You-Yi Xu
Journal of Applied Polymer Science 2005 Volume 97(Issue 1) pp:20-24
Publication Date(Web):20 APR 2005
DOI:10.1002/app.21721
A series of hybrid polyimide–silica hybrids films were prepared by a sol–gel process via the blending of tetrathoxysilane and a coupling reagent in a pyromellitic anhydride/4,4′-oxydianiline (ODA) based poly(amic acid) solution in N,N-dimethylacetamide, the casting of the films, the evaporation of the solvent, and thermal imidization, in that order. Fourier transform infrared, transmission electron microscopy, atomic force microscopy, and thermogravimetric analysis were used to characterize the structure of the obtained hybrids. The dispersion of silica in the hybrids was suggested to be in two states: a dominant network structure and minor discrete aggregate particles. On the basis of the network structure, the mechanical behavior of the hybrids was interpreted. An investigation of the dielectric properties revealed that the dielectric constant of the hybrids increased slowly with the concentration of SiO2. For hybrid films containing 30 wt % SiO2, the constant increased to 4.2 from the value of 3.2 for pure polyimide. Moreover, the incomplete hydrolysis and decomposition of tetrathoxysilane and the coupling reagent were the main factors contributing to the thermal stability and the uncertainty of the dielectric constant of the hybrids. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 20–24, 2005
Co-reporter:Zhikan Yao, Ying Li, Yue Cui, Ke Zheng, Baoku Zhu, Hong Xu, Liping Zhu
Desalination (1 January 2015) Volume 355() pp:91-98
Publication Date(Web):1 January 2015
DOI:10.1016/j.desal.2014.10.030
•Tertiary amine groups containing block copolymers were synthesized via ATRP.•Tertiary amine groups were introduced into PVDF membrane via blending method.•Macromolecules can be separated by the membrane pH-dependently.•The membrane displayed pH-dependent Cr(VI) adsorption property.•The membrane exhibited the Cr(VI) removal ability in filtration process.To obtain ultrafiltration (UF) membranes with multi-functions in permeation, macromolecule sieving and specific heavy metal removal by adsorption, tertiary amine groups containing amphiphilic block copolymers (poly(methyl methacrylate-b-dimethylamino-2-ethyl methacrylate) (P(MMA-b-DMAEMA))) were designed and synthesized. Then the block copolymers were used to fabricate the tertiary amine block copolymer containing blend membranes with poly(vinylidene fluoride) (PVDF) via a non-solvent induced phase separation (NIPS) process. Hydrogen nuclear magnetic resonance (1H NMR) and X-ray photoelectron spectroscopy (XPS) were used to characterize the bulk and the surface layer compositions of the prepared membranes. It was found that P(MMA-b-DMAEMA) stably retained in the blend membranes and greatly enriched onto the surface layers. The pH-dependent performances of the membranes were investigated in details. With the change of pH values, the surface hydrophilicity, water permeation, dextran sieving behaviors and hexavalent chromium (Cr(VI)) adsorption properties varied greatly. And the membrane performed obviously reversible pH-dependent property. From the results, a feasible method could be inferred for fabricating UF membranes with tunable filtration, macromolecule sieving and anion adsorption properties under different pH conditions.Download full-size image
Co-reporter:Xin Kong, Ze-Lin Qiu, Chun-Er Lin, You-Zhi Song, Bao-Ku Zhu, Li-Ping Zhu and Xiu-Zhen Wei
Journal of Materials Chemistry A 2017 - vol. 5(Issue 17) pp:NaN7884-7884
Publication Date(Web):2017/03/21
DOI:10.1039/C7TA00246G
Membranes with both high permeability and selectivity are desirable for practical separation. In this work, three hyperbranched polyesters (HPEs) with different numbers of hydroxyl-terminated groups and molecular structures were, respectively, incorporated into a polyamide film formed by the interfacial reaction between the mixtures of HPE/piperazine (PIP) and trimesoyl chloride (TMC) on PVC hollow fiber substrates to endow the corresponding thin film composite (TFC) membranes with different permselectivity performances. The successful incorporation of HPEs into the cross-linked polyamide matrix and their gradient distribution in the corresponding selective layer were confirmed by ATR-FTIR and XPS analyses. Moreover, the permeation experiments for the fabricated TFC membranes revealed that HPEs most likely existed within the network or/and aggregate pores of the polyamide matrix due to their nanometer sizes and flexible molecular structures. Both the changes in the pore structures and the increase in the hydrophilicity of the polyamide matrix with the introduction of abundant hydroxyl groups pending in the HPE molecules led to the permeate flux of the TFC membrane increasing significantly. Importantly, nearly spherical H40 HPEs with intramolecular cavities could act as a molecular sieve to endow the selective layer with a high rejection capability. Meanwhile, the H40/PIP selective layer with a more negatively charged surface exhibited a higher rejection for SO42− ions while maintaining a low rejection for Cl− ions. These findings encourage further exploration of a new alternative material with such structures like HPE by interfacial polymerization to construct an ultrathin barrier film with high permselectivity performance.
![Poly[(4-oxo-3,1(4H)-phthalazinediyl)-1,4-phenyleneoxy-1,4-phenylenec
arbonyl-1,4-phenylene]](http://img.cochemist.com/ccimg/188700/188675-31-2.png)
![Poly[(4-oxo-3,1(4H)-phthalazinediyl)-1,4-phenyleneoxy-1,4-phenylenec
arbonyl-1,4-phenylene]](http://img.cochemist.com/ccimg/188700/188675-31-2_b.png)
![POLY[OXY(2-AMINO-1,4-PHENYLENE)SULFONYL(3-AMINO-1,4-PHENYLENE)OXY-1,4-PHENYLENESULFONYL-1,4-PHENYLENE]](http://img.cochemist.com/ccimg/62800/62751-10-4.png)
![POLY[OXY(2-AMINO-1,4-PHENYLENE)SULFONYL(3-AMINO-1,4-PHENYLENE)OXY-1,4-PHENYLENESULFONYL-1,4-PHENYLENE]](http://img.cochemist.com/ccimg/62800/62751-10-4_b.png)
![Propanoic acid, 2-[[(ethylthio)thioxomethyl]thio]-2-methyl-](/data/chemimg/113500/881037-62-3.png)
![Propanoic acid, 2-[[(ethylthio)thioxomethyl]thio]-2-methyl-](/data/chemimg/113500/881037-62-3_b.png)
![Poly(oxy-1,4-butanediyl),a-(1-oxo-2-propen-1-yl)-w-[(1-oxo-2-propen-1-yl)oxy]-](http://img.cochemist.com/ccimg/52300/52277-33-5.png)
![Poly(oxy-1,4-butanediyl),a-(1-oxo-2-propen-1-yl)-w-[(1-oxo-2-propen-1-yl)oxy]-](http://img.cochemist.com/ccimg/52300/52277-33-5_b.png)
![2-[4-[(2-chloro-4-nitrophenyl)diazenyl]-n-ethylanilino]ethyl-trimethylazanium;methyl Sulfate](http://img.cochemist.com/ccimg/14300/14254-17-2.png)
![2-[4-[(2-chloro-4-nitrophenyl)diazenyl]-n-ethylanilino]ethyl-trimethylazanium;methyl Sulfate](http://img.cochemist.com/ccimg/14300/14254-17-2_b.png)
![Poly(oxy[1,1'-biphenyl]-4,4'-diyloxy-1,4-phenylenesulfonyl-1,4-phenylene)](/data/chemimg/1105800/25839-81-0.png)
![Poly(oxy[1,1'-biphenyl]-4,4'-diyloxy-1,4-phenylenesulfonyl-1,4-phenylene)](/data/chemimg/1105800/25839-81-0_b.png)
![Tungstate(3-),tetracosa-m-oxododecaoxo[m12-[phosphato(3-)-kO:kO:kO:kO':kO':kO':kO'':kO'':kO'':kO''':kO''':kO''']]dodeca-,hydrogen (1:3)](http://img.cochemist.com/ccimg/1400/1343-93-7.png)
![Tungstate(3-),tetracosa-m-oxododecaoxo[m12-[phosphato(3-)-kO:kO:kO:kO':kO':kO':kO'':kO'':kO'':kO''':kO''':kO''']]dodeca-,hydrogen (1:3)](http://img.cochemist.com/ccimg/1400/1343-93-7_b.png)
