Weifu Dong

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Name: 东为富

Organization: Jiangnan University , China

Department: School of Chemical and Material Engineering

Title: Professor(PhD)

Chemicals
References

A Novel UV-Shielding and Transparent Polymer Film: When Bioinspired Dopamine–Melanin Hollow Nanoparticles Join Polymers

Co-reporter:Yang Wang, Jing Su, Ting Li, Piming Ma, Huiyu Bai, Yi Xie, Mingqing Chen, and Weifu Dong

ACS Applied Materials & Interfaces October 18, 2017 Volume 9(Issue 41) pp:36281-36281

Publication Date(Web):September 25, 2017

DOI:10.1021/acsami.7b08763

Ultraviolet (UV) light is known to be harmful to human health and cause organic materials to undergo photodegradation. In this Research Article, bioinspired dopamine–melanin solid nanoparticles (Dpa-s NPs) and hollow nanoparticles (Dpa-h NPs) as UV-absorbers were introduced to enhance the UV-shielding performance of polymer. First, Dpa-s NPs were synthesized through autoxidation of dopamine in alkaline aqueous solution. Dpa-h NPs were prepared by the spontaneous oxidative polymerization of dopamine solution onto polystyrene (PS) nanospheres template, followed by removal of the template. Poly(vinyl alcohol) (PVA)/Dpa nanocomposite films were subsequently fabricated by a simple casting solvent. UV irradiation protocols were set up, allowing selective study of the extra-shielding effects of Dpa-s versus Dpa-h NPs. In contrast to PVA/Dpa-s films, PVA/Dpa-h films exhibit stronger UV-shielding capabilities and can almost block the complete UV region (200–400 nm). The excellent UV-shielding performance of the PVA/Dpa-h films mainly arises from multiple absorption because of the hollow structure and large specific area of Dpa-h NPs. Moreover, the wall thickness of Dpa-h NPs can be simply controlled from 28 to 8 nm, depending on the ratio between PS and dopamine. The resulting films with Dpa-h NPs (wall thickness = ∼8 nm) maintained relatively high transparency to visible light because of the thinner wall thickness. The results indicate that the prepared Dpa-h NPs can be used as a novel UV absorber for next-generation transparent UV-shielding materials.Keywords: dopamine−melanin; hollow nanoparticles; polymer; transparency; UV-shielding;

Superior Performance of Artificial Nacre Based on Graphene Oxide Nanosheets

Co-reporter:Yang WangHao Yuan, Piming Ma, Huiyu Bai, Mingqing Chen, Weifu Dong, Yi XieYogesh S. Deshmukh

ACS Applied Materials & Interfaces 2017 Volume 9(Issue 4) pp:

Publication Date(Web):January 17, 2017

DOI:10.1021/acsami.6b13834

Natural nacre is well-known by its unique properties due to the well-recognized “bricks-and-mortar” structure. Inspired by the natural nacre, graphene oxide (GO) was reduced by dopamine with simultaneous coating by polydopamine (PDA) in aqueous solution to yield polydopamine-capped reduce GO (PDG). The artificial nacre nanocomposite materials of poly(vinyl alcohol) (PVA) and PDG presenting layered structure had been successfully constructed via a vacuum-assisted assembly process, in which PDG and PVA served as “bricks” and “mortar”, respectively. A combination of hydrogen bonding, strong adhesion and friction between PDG nanosheets and PVA chains resulted in enhancements for mechanical properties. The tensile strength, elongation at break, and toughness of PDG–PVA nanocomposite reached to 327 ± 19.3 MPa, 8 ± 0.2%, and 13.0 ± 0.7 MJ m–3, which is simultaneously 2.4, 8, and 7 times higher than that of nature nacre with 80–135 MPa, ∼1%, and ∼1.8 MJ m–3, respectively. More interestingly, the obtained nanocomposites demonstrated a high anisotropy of thermal conductivity (k∥/k⊥ ≈ 380). Combined with superior mechanical properties and high anisotropy of thermal conductivity make these biomimetic materials promising candidates in aerospace, tissue engineering, and thermal management applications.Keywords: graphene oxide; integrated superior performance; interfacial adhesion; nacre; thermal conductivity;

Hierarchical structural double network hydrogel with high strength, toughness, and good recoverability

Co-reporter:Shuangfei Xiang;Wangqiu Qian;Ting Li;Yang Wang;Mingqing Chen;Piming Ma

New Journal of Chemistry (1998-Present) 2017 vol. 41(Issue 23) pp:14397-14402

Publication Date(Web):2017/11/20

DOI:10.1039/C7NJ03263C

Hierarchical structural double network hydrogel (H-DN gel) was fabricated by inducing ferric coordination crosslinkers in the second network of PAMPS/P(AAm–AAc) double network hydrogel. Investigations of the tensile and compressive properties indicated that the H-DN gel exhibited a dramatic enhancement in the Young's modulus, tensile ultimate strength, toughness, compressive modulus and stress, compared to traditional double network hydrogels. H-DN hydrogel exhibited good recoverability that remained at ∼70% of the initial dissipated energy after resting at 60 °C for 15 min. Finally, scanning electron microscopy (SEM) revealed that the amount of embedded micro-network structures in H-DN gel became more intensive and the walls got thicker.

Enhanced Thermal Stability and UV-Shielding Properties of Poly(vinyl alcohol) Based on Esculetin

Co-reporter:Yang WangChennong Xiang, Ting Li, Piming Ma, Huiyu Bai, Yi Xie, Mingqing Chen, Weifu Dong

The Journal of Physical Chemistry B 2017 Volume 121(Issue 5) pp:

Publication Date(Web):January 13, 2017

DOI:10.1021/acs.jpcb.6b11453

In this article, PVA composites with outstanding thermal stability, UV shielding, and high transparency were fabricated on the basis of traditional Chinese medicine (esculetin). Characterization data have suggested in which the resulting PVA/esculetin (ESC) composites display excellent thermal stability compared to pure PVA and most of the PVA nanocomposites. The pyrolysis mechanism of PVA before and after modification with esculetin varies from chain unzipping degradation followed by chain random scission. The DPPH scavenging activity and FTIR measurements have illustrated that esculetin can scavenge reactive radicals, which leads to improvements in thermal stability and a change in the pyrolysis mechanism of PVA. More importantly, the resulting composites can almost completely block the whole UV region (200–400 nm) without any deterioration of the high transparency of the composites. Therefore, the composites can convert harmful UV light into blue light effectively, which is beneficial for their application as optical materials and devices.

Design of polyurethane acrylic antimicrobial films via one-step UV curing

Co-reporter:Rui Chen;Ting Li;Qi Zhang;Zhongyang Ding;Piming Ma;Shengwen Zhang;Mingqing Chen;Weihua Ming

New Journal of Chemistry (1998-Present) 2017 vol. 41(Issue 18) pp:9762-9768

Publication Date(Web):2017/09/11

DOI:10.1039/C7NJ02023F

We synthesized two reactive quaternary ammonium methacrylate compounds (QAC-10 and QAC-12) bearing hydrophobic tails with different alkyl chain lengths. Cross-linked films with excellent antimicrobial properties were obtained from a mixture of a polyurethane acrylate prepolymer and a reactive QAC via one-step UV curing. The QAC-containing films showed total kill against both Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus epidermidis (S. epidermidis) at QAC-12 concentrations as low as ∼2.5 wt% relative to the polyurethane acrylate prepolymer, which was substantially lower than the QAC amount needed in the films containing QAC-10 with a shorter hydrocarbon tail (C10H21). Compared with the QAC-10-containing films, the higher antimicrobial potency in the QAC-12-containing films was the consequence of the longer hydrophobic alkyl tail (C12H25), which offered a stronger driving force for the surface enrichment of the QAC and, thus, greater surface charge density (the longer tail may also penetrate the cell membrane more easily due to stronger hydrophobic interactions). A zone of inhibition test confirmed that the antimicrobial effect of these films was on the basis of contact killing and there was no leaching of antimicrobial species from the cross-linked films.

Simultaneous Enhancements of UV-Shielding Properties and Photostability of Poly(vinyl alcohol) via Incorporation of Sepia Eumelanin

Co-reporter:Yang Wang, Ting Li, Piming Ma, Huiyu Bai, Yi Xie, Mingqing Chen, and Weifu Dong

ACS Sustainable Chemistry & Engineering 2016 Volume 4(Issue 4) pp:2252

Publication Date(Web):March 13, 2016

DOI:10.1021/acssuschemeng.5b01734

Sepia eumelanin (SE), a biomacromolecule, was developed to prepare the excellent UV-shielding polymer material with better photostability. UV–vis transmittance spectra showed that poly(vinyl alcohol) PVA/SE film blocked most ultraviolet light below 300 nm even with a low concentration of SE (0.5 wt %), which still kept its high transparency in the visible spectrum. Rhodamine B photodegradation measurement further confirmed the excellent UV-shielding properties of PVA/SE film. FTIR indicated that the carbonyl absorption bands resulting from phtodegradation for PVA/SE film did not change after UV exposure for 2700 h. The tensile properties of neat PVA were deceased intensely after UV irradiation; however, those of PVA/SE film were reduced a little. Moreover, AFM indicated that the surface roughness of PVA/SE film was much lower than that of a neat PVA one. It could be concluded that SE reduced the PVA degradation rate dramatically, revealing enhanced photostability of PVA/SE film. The mechanism for outstanding UV-shielding properties and photostability of PVA/SE film was illuminated, based on the formation of charge transfer complexes (CTCs) between SE and PVA, photothermal conversion, and the well-known radical scavenging capabilities of SE.Keywords: Photostability; Poly(vinyl alcohol); Sepia eumelanin; UV-shielding;

Preparation and properties of thermoplastic poly(caprolactone) composites containing high amount of esterified starch without plasticizer

Co-reporter:Yujie Sun, Qiongen Hu, Jiangtao Qian, Ting Li, Piming Ma, Dongjian Shi, Weifu Dong, Mingqing Chen

Carbohydrate Polymers 2016 Volume 139() pp:28-34

Publication Date(Web):30 March 2016

DOI:10.1016/j.carbpol.2015.12.002

•Stearyl chloride was effective to fabricate esterified starch.•The torque of PCL/esterified starch (80/20, wt) was low during melt blending.•PCL/esterified starch (80 wt%) exhibited the improved tensile properties.Based on stearyl chloride and native starch, esterified starch were prepared and the chemical structure was characterized by 1H NMR and FTIR. It was found that stearyl chloride was an efficient agent to fabricate esterified starch with high degree of substitution (DS). During the melt blending of esterified starch (80 wt%) and poly(caprolactone) (PCL, 20 wt%), it was shown the torque of PCL/esterified starch was much lower than that of PCL/native starch without any plasticizer, and further decreased with increasing DS. Compared with PCL/native starch, the tensile properties of PCL/esterified starch composites were significantly enhanced. The tensile strength and elongation at break were increased from 2.7 MPa to 56% for PCL/native starch composites to 9.1 MPa and 626% for PCL/esterified starch ones with DS of 1.50, respectively. SEM observation revealed the esterified starch particles in matrix became smaller and more uniform. In addition, the water resistance and hydrophobic character of PCL/esterified starch composites were improved. PCL composites containing 80 wt% esterified starch with favorable mechanical properties would have great potential applications in broad areas.

Superior Performance of Polyurethane Based on Natural Melanin Nanoparticles

Co-reporter:Yang Wang, Ting Li, Xuefei Wang, Piming Ma, Huiyu Bai, Weifu Dong, Yi Xie, and Mingqing Chen

Biomacromolecules 2016 Volume 17(Issue 11) pp:3782

Publication Date(Web):October 17, 2016

DOI:10.1021/acs.biomac.6b01298

Melanin, a kind of well-known multifunctional biomacromolecules that are widely distributed in natural sources. In this work, polyurethane (PU)/melanin nanocomposites with enhanced tensile strength and toughness were successfully fabricated via in situ polymerization. It was found that the tensile strength (σ), elongation-at-break (εmax), and toughness (W) were improved from 5.6 MPa, 770%, and 33 MJ/m3 for PU to 51.5 MPa, 1880%, and 413 MJ/m3 for PU/melanin (2 wt %) nanocomposite, respectively. Micromorphology indicated that individualized melanin nanoparticles were specifically linked to the hard domains of PU chains and fine dispersed in matrix. FTIR, DSC, and AFM results suggested melanin induced an improvement in degree of phase separation, which resulted in remarkable enhancements in mechanical properties of PU. However, with further increasing content of melanin, a relatively large-scale phase separation was formed and led to a decrease in mechanical properties of PU. In addition, interactions between melanin and hard segments of PU were increased, leading to a higher TgHS. Moreover, the dynamic mechanical properties and rheological behavior of PU/melanin nanocomposites were further investigated.

Strong nanocomposite reinforcement effects in poly(vinyl alcohol) with melanin nanoparticles

Co-reporter:Yang Wang, Zhu Wang, Piming Ma, Huiyu Bai, Weifu Dong, Yi Xie and Mingqing Chen

RSC Advances 2015 vol. 5(Issue 89) pp:72691-72698

Publication Date(Web):21 Aug 2015

DOI:10.1039/C5RA12333J

Poly(vinyl alcohol)/melanin nanocomposites with improved tensile strength, Young's modulus and heat distortion temperature (HDT) were prepared by using simple aqueous solution mixing. When incorporated into PVA with low content (0.5–2 wt%), melanin nanoparticles dramatically enhanced the mechanical properties of PVA. With addition of 2 wt% melanin, the nanocomposites exhibited a tensile strength (σ) of 155 MPa and a Young's modulus (E) of 2.95 GPa, which were much higher than these of neat PVA. HDT was enhanced from 56.5 °C to 100 °C. TEM indicated that melanin nanoparticles were uniformly dispersed in PVA without aggregation. The strong hydrogen bonding between the –OH (or –NH–) of melanin and –OH of PVA confirmed by FTIR, which played a key factor to prevent the aggregation of nanoparticles in PVA matrix and made a contribution to the high performance of PVA.

Preparation of polyvinyl alcohol/chitosan hydrogel compounded with graphene oxide to enhance the adsorption properties for Cu(II) in aqueous solution

Co-reporter:Luzhong Li;Zhu Wang;Piming Ma;Huiyu Bai

Journal of Polymer Research 2015 Volume 22( Issue 8) pp:

Publication Date(Web):2015 August

DOI:10.1007/s10965-015-0794-3

A novel bio-adsorbent, composite hydrogel beads, composed of polyvinyl alcohol (PVA), chitosan (CS) and graphene oxide (GO) was prepared by an instantaneous gelation method. The micromorphology and thermal stability of the PVA/CS/GO hydrogel beads were characterized by scanning electronic microscope (SEM) and thermo gravimetric analysis (TGA) respectively. Adsorption of Cu(II) onto PVA/CS/GO hydrogel beads was investigated with respect to pH, initial concentration, temperature and adsorption time. Adsorption data were well matched by Langmuir isotherm and pseudo-second-order kinetic model at the optimum pH 5.5. The maximum adsorption capacities of PVA/CS/GO hydrogel beads were found to be 162 mg g−1 for Cu(II) at 30 °C, which was much higher than that of PVA/CS hydrogel. Thermodynamic studies indicated that the adsorption was spontaneous and endothermic process in nature. Besides, desorption efficiency and reusability of the adsorbents were assessed on basis of six consecutive adsorption-desorption cycles. Based on these studies, it can be seen that PVA/CS/GO hydrogel beads will be a potential recyclable adsorbent for removal of hazardous metal ions in waste water.

Nanocomposite hydrogel consisting of Na-montmorillonite with enhanced mechanical properties

Co-reporter:Ting Li;Shuangfei Xiang;Piming Ma;Huiyu Bai;Mingqing Chen

Journal of Polymer Science Part B: Polymer Physics 2015 Volume 53( Issue 14) pp:1020-1026

Publication Date(Web):

DOI:10.1002/polb.23732

ABSTRACT

A new kind of nanocomposite (NC) hydrogel with Na-montmorillonite (MMT) is presented in this article. The NC hydrogels were synthesized by free radical copolymerization of acrylamide and (3-acrylamidopropyl) trimethylammonium chloride (ATC) in the presence of MMT and N,N′-methylene-bis-acrylamide used as chemical cross-linker. Due to the cation-exchange reaction between MMT and ATC (cationic monomer) during the synthesis of NC hydrogels, MMT platelets were considered chemical “plane” cross-linkers, different from “point” cross-linkers. With increasing amount of MMT, the crosslinking degree enhanced, causing a decrease of the swelling degree at equilibrium. Investigations of mechanical properties indicated that NC hydrogels exhibited enhanced strength and toughness, which resulted from chemical interaction between exfoliated MMT platelets and polymer chains in hydrogels. Dynamic shear measurements showed that both storage modulus and loss modulus increased with increasing MMT content. The idea described here provided a new route to prepare hydrogels with high mechanical properties by using alternative natural Na-MMT. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 1020–1026

Novel poly(xylitol sebacate)/hydroxyapatite bio-nanocomposites via one-step synthesis

Co-reporter:Piming Ma, Ting Li, Wei Wu, Dongjian Shi, Fang Duan, Huiyu Bai, Weifu Dong, Mingqing Chen

Polymer Degradation and Stability 2014 110() pp: 50-55

Publication Date(Web):

DOI:10.1016/j.polymdegradstab.2014.08.014

Hydrolyzable and bio-based polyester/nano-hydroxyapatite nanocomposites: Structure and properties

Co-reporter:Weifu Dong, Jingjiao Ren, Dongjian Shi, Piming Ma, Xiao Li, Fang Duan, Zhongbin Ni, Mingqing Chen

Polymer Degradation and Stability 2013 Volume 98(Issue 9) pp:1790-1795

Publication Date(Web):September 2013

DOI:10.1016/j.polymdegradstab.2013.05.015

Hydrolyzable and bio-based poly(DHCA-co-HDA) (PDH)/nano-hydroxyapatite (n-HA) nanocomposites were fabricated by polycondensation of 3,4-dihydroxycinnamic acid (DHCA) and 10-hydroxydecanoic acid (HDA) with various amount of n-HA. The structure of nanocomposites was characterized by FT-IR. DSC results indicated that the Tgs of the nanocomposites were improved with increasing n-HA content. The SEM micromorphology revealed that n-HA nano-particles were well dispersed in PDH, which was due to the good compatibility between n-HA and PDH. With addition of n-HA in PDH, the tensile strength of nanocomposites prominently enhanced, however the elongation at break reduced. The presence of n-HA increased the hydrophilicity and hydrolysis rate of PDH/n-HA nanocomposites. Moreover, the hydrophilicity and degradation rate of nanocomposites can be altered through varying the content of n-HA.

Influence of phthalic anhydride and bioxazoline on the mechanical and morphological properties of biodegradable poly(lactic acid)/poly[(butylene adipate)-co-terephthalate] blends

Co-reporter:Weifu Dong;Benshu Zou;Piming Ma;Wangcheng Liu;Xin Zhou;Dongjian Shi;Zhongbin Ni ;Mingqing Chen

Polymer International 2013 Volume 62( Issue 12) pp:1783-1790

Publication Date(Web):

DOI:10.1002/pi.4568

Abstract

Poly(lactic acid) (PLA)/poly[(butylene adipate)-co-terephthalate] (PBAT) blends were fabricated by melt blending, with 2,2′-(1,3-phenylene)bis(2-oxazoline) (BOZ) and phthalic anhydride (PA) used as compatibilizers. It was found that a small amount of BOZ or PA greatly increased the elongation at break of the PLA/PBAT blends without sacrificing their high tensile strength. Scanning electron microscopy results revealed that the PBAT particles became finer and were uniformly dispersed in the matrix when the compatibilizers were incorporated, which indicated that the interfacial bonding and compatibilization between PLA and PBAT were improved in the presence of the compatibilizers. Compared with PLA/PBAT blends, the molecular weight of PLA/PBAT/PA/BOZ blends was increased due to chain-extending reactions. Differential scanning calorimetry results suggested PBAT decreased the crystallization rate and crystallinity of PLA in the blends. Moreover, the glass transition temperature of PBAT was further decreased when the compatibilizers were used. © 2013 Society of Chemical Industry