LiFen Zhang

Name: 张丽芬; LiFen Zhang

Organization: Soochow University , China

Department: Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application, Department of Polymer Science and Engineering, College of Chemistry, Chemical Engineering and Materials Science

Title: Professor(PhD)

TOPICS

Polymer

RAFT Block Copolymer Atom Transfer Radical Polymerization Radical Polymerization Phosphorus Flame Retardant

Material Chemistry

Physical Chemistry

heterogenous catalysis

Organic Chemistry

Phosphorus Flame Retardant

Chemicals
References

Facile synthesis of poly(vinyl acetate)-b-polystyrene copolymers mediated by an iniferter agent using a single methodology

Co-reporter:Mengqi Wang;Xiaowu Jiang;Yanjing Luo;Zhenping Cheng;Xiulin Zhu

Polymer Chemistry (2010-Present) 2017 vol. 8(Issue 38) pp:5918-5923

Publication Date(Web):2017/10/03

DOI:10.1039/C7PY01222E

The preparation of well-defined block copolymers from both non-conjugated and conjugated monomers is still challenging. In this work, a typical block copolymer poly(vinyl acetate) (PVAc)-b-polystyrene (PS) was successfully synthesized by using a successive iniferter strategy. Herein, PVAc was first obtained in the presence of an iniferter agent (e.g., 1-cyano-1-methylethyldiethyldithiocarbamate (MANDC), 2-(N,N-diethyldithiocarbamyl)-isobutyric acid ethyl ester (EMADC) or 2-(ethoxycarbonothioyl)sulfanyl propanoate (EXEP)). Then the resultant PVAc with high end-group functionalities could be used as an effective macroiniferter agent for the polymerization of styrene (St). The kinetic studies of the chain extension experiment with St indicated the “living” features of the polymerization system. In addition, the obtained PVAc-b-PS copolymers could be easily converted into PVA-b-PS amphiphiles by methanolysis of the poly(vinyl acetate) block. Importantly, the synthesis of the copolymers just uses a single simple and metal-free catalyzed polymerization method, which may be of great potential for industrial production.

Visible-light-induced living radical polymerization using in situ bromine-iodine transformation as an internal boost

Co-reporter:Xiaodong Liu;Qinghua Xu;Zhenping Cheng;Xiulin Zhu

Polymer Chemistry (2010-Present) 2017 vol. 8(Issue 16) pp:2538-2551

Publication Date(Web):2017/04/18

DOI:10.1039/C7PY00366H

A facile and effective visible-light-induced living radical polymerization (LRP) system was successfully developed at room temperature using typical alkyl bromides (such as ethyl α-bromophenylacetate (EBPA) and 2-bromopropanenitrile (BPN)) as the initiator in the presence of sodium iodide (NaI) for the first time. Water-soluble poly(ethylene glycol) methyl ether methacrylate (PEGMA) was used as the model monomer. By investigating the influencing factors including initiator and solvent type, solvent volume, light source, activator (sodium iodide) and catalyst (triethylamine) concentration, and degree of polymerization (DP), optimized polymerization conditions could be established. Excellent control over molecular weights and distributions (Mw/Mn = 1.05–1.33) of the polymers was achieved under light-emitting diode (LED) irradiation. In addition, the moderate polymerization rate could be drastically promoted in the presence of triethylamine (TEA) as the catalyst. This polymerization system exhibited instantaneous control in response to the on–off switch of the irradiation stimulus. Various types of other monomers (such as methyl methacrylate (MMA) and glycidyl methacrylate (GMA)) and illumination sources (especially sunlight) also proved to be compatible with this LRP system. The possible polymerization mechanism was investigated, and the bromine-iodine transformation activated LRP in this study will enable the facile preparation of well-defined materials with satisfactory controllability and versatile architectures.

The in situ formation of nanoparticles via RAFT polymerization-induced self-assembly in a continuous tubular reactor

Co-reporter:Jinying Peng;Chun Tian;Zhenping Cheng;Xiulin Zhu

Polymer Chemistry (2010-Present) 2017 vol. 8(Issue 9) pp:1495-1506

Publication Date(Web):2017/02/28

DOI:10.1039/C6PY02133F

In this work, the amphiphilic poly(poly(ethylene glycol)methyl ether methacrylate)-b-poly(methyl methacrylate) (PPEGMA-b-PMMA) block copolymer nanoparticles were successfully synthesized via polymerization-induced self-assembly (PISA) at 70 °C in a continuous tubular reactor (TR) with a mixed solvent of water and ethanol, using 4-cyano-4-(thiobenzoylthio)pentanoic acid (CPADB) as the chain transfer agent and 2,2′-azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride (AIBI) as the initiator. It was found that the addition of a high amount of water (56% v/v) hindered the transition of the copolymer morphology with only spheres being obtained. In addition, different mixers were used to investigate the effect of the mixing intensity on the evolution of the copolymer morphology with the increasing degree of polymerization (DP) of the resultant PMMA. When a T-joint was used to make PPEGMA macro-CTA (synthesized in the first stage tube) and MMA join together and flow into the second stage tube, an approximately constant particle diameter was observed during the polymerization process. In contrast, the use of a static mixer resulted in kinetically-trapped spheres. Furthermore, the particle diameter gradually increased with the increasing target DP of the PMMA, which was controlled by varying the concentration of the PPEGMA macro-CTA solution.

Synthesis of soap-free emulsion with high solid content by differential dripping RAFT polymerization-induced self-assembly

Co-reporter:Juanjuan Wu;Chun Tian;Zhenping Cheng;Xiulin Zhu

RSC Advances (2011-Present) 2017 vol. 7(Issue 11) pp:6559-6564

Publication Date(Web):2017/01/18

DOI:10.1039/C6RA27290H

Polymerization induced self-assembly (PISA) has been a facile and effective approach to prepare highly concentrated block copolymer nano-objects in situ. In this work, a soap-free emulsion with high solid content (60%) was successfully prepared in a semi-batch monomer addition manner. High monomer conversion can also be obtained by adjusting the dripping time. At first, a hydrophilic polymer, poly(poly(ethylene glycol)monomethyl ether methacrylate) (PPEGMA) was synthesized at almost complete monomer conversion in order to be used as a macroRAFT agent without any purification in the following step. Then PPEGMA was chain extended by the second monomer, methyl methacrylate (MMA), added at a very slow rate to form diblock copolymers and further self-assembled into nanoparticles in situ. The resulting latexes were very stable and the particle sizes remained at the nanoscale.

Synthesis of highly proton-conductive poly(arylene ether sulfone) bearing perfluoroalkyl sulfonic acids via polymer post-modification

Co-reporter:Yafeng Zeng, Liang Gu, Lifen Zhang, Zhenping Cheng, Xiulin Zhu

Polymer 2017 Volume 123(Volume 123) pp:

Publication Date(Web):11 August 2017

DOI:10.1016/j.polymer.2017.07.037

•Poly(arylene ether sulfone) bearing perfluoroalkyl sulfonic acid groups was designed and synthesized.•Microstructural morphology of the title membrane held highly hydrophilic/hydrophobic phase-separation.•The title membrane exhibited higher proton conductivity to Nafion 117.Proton exchange membranes (PEMs) are key materials in PEM fuel cells (PEMFCs), and play a key role in battery performance. Herein, a versatile and facile synthetic approach to aromatic-based polymer bearing perfluoroalkyl sulfonic acid groups via polymer post-modification (PPM) is described. Characterization of the desired aromatic-based ionomer has been carefully carried out by 1H, 19F NMR and FT-IR. Tough, flexible, and transparent membrane with ion exchange capacity (IEC) value of 1.78 mequiv g−1 is obtained by solution casting, exhibit excellent thermal stability, mechanical properties and moderate oxidative stability. Morphology observation by atomic force microscopy (AFM) and small angle X-ray scattering (SAXS) reveals that the title membrane holds highly hydrophilic/hydrophobic phase-separation and hydrophilic domains partly connect to each other, which is similar to that of the benchmark perfluorosulfonic acid ionomers (e.g., Nafion). Meanwhile, the membrane have a higher water uptake (58.6%) and swelling ratio (23.9%) compared to Nafion (27.1%, 12.9%, respectively) in hydrated state at 60 °C. Furthermore, the aromatic-based polymer bearing perfluoroalkyl sulfonic acids show higher proton conductivity comparable to that of Nafion under full hydrated conditions in the range of tested temperatures. Single cell tests have shown that the membrane has a moderate fuel cell performance with maximum power density of 300 mW/cm−2 at 40 °C and 80% RH, 400 mW/cm−2 at 60 °C and 80% RH.Download high-res image (176KB)Download full-size image

Photocatalyzed iron-based ATRP of methyl methacrylate using 1,3-dimethyl-2-imidazolidinone as both solvent and ligand

Co-reporter:Jian Wu;Zhenping Cheng;Xiulin Zhu

RSC Advances (2011-Present) 2017 vol. 7(Issue 7) pp:3888-3893

Publication Date(Web):2017/01/09

DOI:10.1039/C6RA27307F

Photochemistry serves as a wonderful means to facilitate various chemical reactions and is indeed unique in its powerful ability to meet the energetic requirements for conducting processes that would not be accomplished using thermal counterparts. In this work, a novel photocatalyzed Fe-based atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) was performed under UV irradiation, using ethyl 2-bromophenylacetate (EBPA) as the initiator, FeBr2 as the catalyst and 1,3-dimethyl-2-imidazolidinone (DMI) as both the solvent and ligand. The rate of the polymerization was relatively fast, as monomer conversion reached 91.2% at room temperature under UV irradiation (900 μW cm−2) at 360 nm within 26 h. Even when the target degree of polymerization was up to 1000, the molecular weight distribution obtained remained narrow and the molecular weight (Mn,GPC) was close to the corresponding theoretical value (Mn,th). The polymerization kinetics was studied in detail and the “living” features of this system were confirmed by performing successful chain extension experiments.

The positive effect of water on photo-induced step transfer-addition & radical-termination (START) polymerization

Co-reporter:Tianchi Xu;Zhenping Cheng;Xiulin Zhu

RSC Advances (2011-Present) 2017 vol. 7(Issue 29) pp:17988-17996

Publication Date(Web):2017/03/20

DOI:10.1039/C7RA01925D

Step-growth radical copolymerization between α,ω-diiodoperfluoroalkanes (A) and α,ω-unconjugated dienes (B) proceeds efficiently through a photo-induced Step Transfer-Addition & Radical-Termination (START) strategy in aqueous/organic biphasic system. The addition of water in our polymerization strategy enhanced the overall polymerization efficiency and inhibited the function loss (C–I) significantly, which has been illustrated through UV-vis tests. Therefore, most of the functional groups (C–I) in the polymer chain end have been preserved in the final polymer product (AB)n based on 19F NMR analysis. After polymerization, we could erase the iodine atoms in the main chain of (AB)n, which generates semifluorinated polyolefins with enhanced thermal stability.

Visible light-induced PET-RAFT polymerization of methacrylates with novel organic photocatalysts

Co-reporter:Kai Tu;Tianchi Xu;Zhenping Cheng;Xiulin Zhu

RSC Advances (2011-Present) 2017 vol. 7(Issue 39) pp:24040-24045

Publication Date(Web):2017/05/03

DOI:10.1039/C7RA03103C

Light-emitting diode (LED) technology in the visible spectrum holds great promise for photopolymerization because of its characteristic virtues such as low energy consumption, no ozone release, low heat generation, simple and safe operation, high performance, etc. In this work, two organic agents, 4-methoxybenzaldehyde (PC1) and 2,4,6-tri-(p-methoxyphenyl) pyrylium tetrafluoroborate (PC2), were employed as the photocatalysts for the photoinduced electron transfer-reversible addition–fragmentation chain transfer (PET-RAFT) polymerization under irradiation of various LED lights (purple, blue and white LEDs) at room temperature, using methyl methacrylate (MMA) as the model monomer and typical 2-cyanoprop-2-yl 1-dithionaphthalate (CPDN) as the RAFT agent. It has been found that the polymerization could be carried out smoothly with a wide range of wavelengths of visible light and could be extended to other methacrylates such as ethyl methacrylate (EMA) and n-butyl methacrylate (n-BMA). In addition, the “living” feature of this polymerization system was demonstrated by its polymerization kinetics and was confirmed by a chain-extension experiment.

Insight into the polymerization mechanism of photoinduced step transfer-addition & radical-termination (START) polymerizations

Co-reporter:Tianchi Xu;Zhenping Cheng;Xiulin Zhu

Polymer Chemistry (2010-Present) 2017 vol. 8(Issue 26) pp:3910-3920

Publication Date(Web):2017/07/04

DOI:10.1039/C7PY00709D

Photoinduced step transfer-addition & radical-termination (START) polymerization is a newly developed polymerization strategy for the preparation of perfluorocarbon-containing alternating copolymers and was carried out under irradiation with blue light emitting diodes (LEDs) at room temperature (25 °C). In this work, the polymerization efficiency was further enhanced through optimization of the solvent system and construction of an efficient catalytic system: Ru(bpy)3Cl2/reducing agent (RA). In dimethyl carbonate (DMC)/acetonitrile (MeCN), the polyaddition between α,ω-diiodoperfluoroalkanes A and α,ω-unconjugated dienes B predominated over the chain transfer reaction, generating the target polymer product (AB)n with a relatively high molecular weight. Detailed analyses of a template reaction revealed the intrinsic polymerization mechanism of the START process. Based on a comprehensive investigation of the polymerization process, guidelines for the selection of appropriate RAs (e.g., L(+)-ascorbic acid sodium salt (AsAc-Na) and Fe(0)) are provided herein.

Real-time monitoring of a controlled drug delivery system in vivo: construction of a near infrared fluorescence monomer conjugated with pH-responsive polymeric micelles

Co-reporter:Li Chen, Bizheng Chen, Xiaodong Liu, Yujie Xu, Lifen Zhang, Zhenping Cheng and Xiulin Zhu

Journal of Materials Chemistry A 2016 vol. 4(Issue 19) pp:3377-3386

Publication Date(Web):19 Apr 2016

DOI:10.1039/C6TB00315J

Real-time monitoring of drug delivery systems has attracted growing interest for potential applications in biomedical therapy. Fluorescence imaging is a highly sensitive technique for illuminating the pathways of such systems. In this work, we designed and synthesized a new near infrared (NIR) fluorescent dye monomer (NFM). The NFM monomer was covalently attached to a pH-responsive amphiphilic block copolymer by reversible addition–fragmentation chain transfer (RAFT) copolymerization using hydrophilic poly(poly(ethylene glycol) methyl ether methacrylate) (PPEGMA) as the macro-RAFT agent and pH-responsive 2-(4-(dodecyloxy)phenyl)-1,3-dioxan-5-yl methacrylate (DBAM) and NFM as the comonomer, to synthesize the multifunctional amphiphilic block copolymer PPEGMA-b-P(DBAM-co-NFM) with NIR moieties and pH-sensitive groups. The PPEGMA-b-P(DBAM-co-NFM) could be self-assembled easily into stable micelles with doxorubicin (DOX) with an average diameter of 66 nm in water. The nano-size of the micelles is suitable for cycling through the body and carrying drugs to tumor sites safely via the enhanced permeability and retention (EPR) effect. Confocal laser scanning microscopy (CLSM) results indicated cells’ uptake and the intracellular distribution. In vivo imaging of the micelles was observed in real time and the fluorescent signals clearly demonstrated the dynamic process of tumor treatment. This versatile and effective strategy is a potential tool for monitoring controlled drug delivery for tumor treatment.

Catalyst-free iodine-mediated living radical polymerization under irradiation over a wide visible-light spectral scope

Co-reporter:Xiaodong Liu, Lifen Zhang, Zhenping Cheng and Xiulin Zhu

Polymer Chemistry 2016 vol. 7(Issue 21) pp:3576-3588

Publication Date(Web):25 Apr 2016

DOI:10.1039/C6PY00444J

Catalyst-free iodine-mediated living radical polymerization (LRP) employing the formation equilibrium between an alkyl iodide dormant species (Polymer-I) and a propagating radical (Polymer˙) over a wide visible light irradiation scope was studied with respect to its kinetics, mechanism and suitability. The polymerization of methyl methacrylate (MMA) or some functional methacrylates offered good control over the polymer molecular weights and distributions (Mw/Mn = 1.05–1.30) up to fairly high conversions (more than 95%). This polymerization system displayed instantaneous activation and deactivation in response to “on–off” switch of the irradiation source. The polymerization kinetic rate was sensitively modulated by tuning the irradiation wavelength. Attractive features of the developed polymerization system include the feasibility of use of irradiation in the visible light spectral scope, good polydispersity control, good tolerance to functional groups, satisfactory regulation over a wide range of wavelengths, environmental safety and external photo-irradiation response sensitivity. Sunlight was also proved to be an alternative illumination source for this iodine-mediated LRP.

Synthesis of amphiphilic nanoparticles and multi-block hydrophilic copolymers by a facile and effective “living” radical polymerization in water

Co-reporter:Juanjuan Wu, Hongjuan Jiang, Lifen Zhang, Zhenping Cheng and Xiulin Zhu

Polymer Chemistry 2016 vol. 7(Issue 14) pp:2486-2491

Publication Date(Web):15 Feb 2016

DOI:10.1039/C6PY00199H

“Living” radical polymerization (LRP) has been a facile method for the preparation of polymers with controlled molecular weights and low polydispersities. This work presents a simple and efficient LRP technique using copper(II) acetate (Cu(OAc)2) and hydrophilic 4-cyano-4-((diethylcarbamothioyl)thio) pentanoic acid (MANDC-COOH) to prepare amphiphilic nanoparticles and multiblock polymers in water. By this technique, firstly, soap-free emulsion polymerization was carried out successfully by using the synthesized poly(poly(ethylene glycol) monomethyl ether methacrylate) (PPEGMA) as the macro-initiator and emulsion stabilizer, and methyl methacrylate (MMA) or styrene (St) as the hydrophobic monomer by sequential addition, which permits amphiphilic copolymer self-assembling in situ into sphere nanoparticles; secondly, a hydrophilic deca-block homopolymer, poly(potassiumsulfopropylmethacrylate) (PSPMA) and an alternating hepta-block copolymer, poly(potassiumsulfopropylmethacrylate)-alt-poly(sodium methacrylate) (PSPMA-alt-PNaMA) by sequential addition of monomers were synthesized smoothly in water for the first time.

Metal-free photoinduced electron transfer–atom transfer radical polymerization (PET–ATRP) via a visible light organic photocatalyst

Co-reporter:Xiaodong Liu, Lifen Zhang, Zhenping Cheng and Xiulin Zhu

Polymer Chemistry 2016 vol. 7(Issue 3) pp:689-700

Publication Date(Web):26 Nov 2015

DOI:10.1039/C5PY01765C

The development of an atom transfer radical polymerization (ATRP) system without any transition metal catalyst for electronic and biomedical applications was considered to be in pressing need. Fluorescein (FL) was used as the organic photocatalyst for the polymerization of methyl methacrylate (MMA) via the proposed photoinduced electron transfer–atom transfer radical polymerization (PET–ATRP) mechanism. In the presence of electron donors provided by triethylamine (TEA), fluorescein can activate alkyl bromide and control radical polymerizations by a reductive quenching pathway. The polymerizations could be controlled by an efficient activation and deactivation equilibrium while maintaining the attractive features of “living” radical polymerization. The number-average molecular weight Mn,GPC increased with monomer conversion, and the controllability of molecular weight distributions for the obtained PMMA could be achieved in the polymerization processes. MALDI-TOF MS, 1H NMR spectroscopy and chain extension polymerizations show reserved chain-end functionality in the synthesized polymers and further confirm the “living” feature of the metal-free ATRP methodology. All these research results support the feasibility of the visible light mediated metal-free PET–ATRP platform for the synthesis of elegant macromolecular structures.

Highly Efficient and Facile Photocatalytic Recycling System Suitable for ICAR ATRP of Hydrophilic Monomers

Co-reporter:Xiaowu Jiang;Zhenping Cheng;Xiulin Zhu

Macromolecular Rapid Communications 2016 Volume 37( Issue 16) pp:1337-1343

Publication Date(Web):

DOI:10.1002/marc.201600215

A Facile Strategy for Catalyst Separation and Recycling Suitable for ATRP of Hydrophilic Monomers Using a Macroligand

Co-reporter:Xiaowu Jiang;Jian Wu;Zhenping Cheng;Xiulin Zhu

Macromolecular Rapid Communications 2016 Volume 37( Issue 2) pp:143-148

Publication Date(Web):

DOI:10.1002/marc.201500439

RAFT copolymerization of a phosphorus-containing monomer with α-hydroxy phosphonate and methyl methacrylate

Co-reporter:Chun Tian, Tianchi Xu, Lifen Zhang, Zhenping Cheng and Xiulin Zhu

RSC Advances 2016 vol. 6(Issue 41) pp:34659-34665

Publication Date(Web):31 Mar 2016

DOI:10.1039/C6RA02809H

Phosphorus-containing polymers have been found wide applications in many fields. In this work, a new kind of phosphorus-containing monomer with α-hydroxy phosphonate 4-((diethoxyphosphoryl)(hydroxy)methyl)phenyl methacrylate (PHMA) was firstly synthesized, and then copolymerization of PHMA and methyl methacrylate (MMA) was carried out via reversible addition–fragmentation chain transfer (RAFT) polymerization. The copolymerization kinetics and successful chain-extension reaction using the resultant PPHMA-co-PMMA confirmed the features of “living”/controlled radical polymerization. According to the thermal gravimetric analyzer (TGA) test, the thermal stability of the resultant phosphorus-containing copolymers increased significantly compared to the conventional methacrylate polymer materials due to the attachment of the phosphonate groups into the side chain of the copolymers. In addition, its superior flame-retardant performance was verified by the micro-scale combustion calorimetry (MCC) test. Meanwhile, the hydrophilicity of the phosphorus-containing copolymers was reflected by water contact angle measurement.

Facilely Recyclable Cu(II) Macrocomplex with Thermoregulated Poly(ionic liquid) Macroligand: Serving as a Highly Efficient Atom Transfer Radical Polymerization Catalyst

Co-reporter:Bingjie Zhang, Lan Yao, Xiaodong Liu, Lifen Zhang, Zhenping Cheng, and Xiulin Zhu

ACS Sustainable Chemistry & Engineering 2016 Volume 4(Issue 12) pp:

Publication Date(Web):October 17, 2016

DOI:10.1021/acssuschemeng.6b01961

Copolymer poly(ionic liquids) (PILs) are fascinating new polymerized polyelectrolytes that can provide the properties of ionic liquids with others combined into one. In this work, a thermoregulated random copolymer PIL (PILL) with the side chains of both ionic liquids and atom transfer radical polymerization (ATRP) ligands was designed and synthesized to form a macrocomplex with CuBr2 and serve as an ATRP catalyst to establish a thermoregulated phase separated catalysis (TPSC) system and further applied in a typical ICAR (initiators for continuous activator regeneration) ATRP process for the catalyst separation and recycling in situ for the first time. This novel TPSC system could simultaneously recycle transition metal catalyst and ligand easily just by changing temperature from polymerization temperature to room temperature. Additionally, even if the highly efficient recyclable PILL with Cu catalyst was separated facilely and reused 10 times in situ, it nearly did not sacrifice the controllability over polymerization. Furthermore, after polymerization and a TPSC process, the metal catalyst residual in the polymer solution phase remained just about 1.5 ppm, indicating highly efficient transition metal catalyst recycling efficiency.Keywords: Atom transfer radical polymerization (ATRP); Catalyst recycle; Copolymer PILs; Living radical polymerization; Macroligand; Thermoregulated phase separated catalysis (TPSC);

Fe(III)-mediated ICAR ATRP in a p-xylene/PEG-200 biphasic system: facile and highly efficient separation and recycling of an iron catalyst

Co-reporter:Bingjie Zhang, Xiaowu Jiang, Lifen Zhang, Zhenping Cheng and Xiulin Zhu

Polymer Chemistry 2015 vol. 6(Issue 37) pp:6616-6622

Publication Date(Web):30 Jul 2015

DOI:10.1039/C5PY01045D

Iron catalysts are attractive catalysts for atom transfer radical polymerization (ATRP) owing to their abundancy, low toxicity and good biocompatibility. However, the recycling of iron catalysts is still a great challenge although the recycling of copper catalysts has achieved success. In this work, we develop a facile and highly efficient separation and recycling strategy for an iron catalyst combining thermoregulated phase separable catalysis (TPSC) and initiators for continuous activator regeneration for atom transfer radical polymerization (ICAR ATRP) in a PEG-200/p-xylene biphasic system. Herein, FeCl3·6H2O was used as the catalyst, tetrabutylammonium bromide (TBABr) as the ligand, 2,2′-azobisisobutyronitrile (AIBN) as the reducing agent, ethyl-2-bromo-2-phenyl acetate (EBPA) as the initiator, and methyl methacrylate (MMA) as the model monomer. The PEG-200/p-xylene biphasic system formed a homogeneous polymerization solution at 70 °C, and the iron catalyst could be easily separated in situ just by a simple standing and decantation process, and was therefore recycled for the next polymerization when the polymerization temperature decreased to room temperature. In this novel polymerization system, well-defined PMMA with controlled molecular weights and narrow molecular weight distributions could be easily obtained, and the iron catalyst could be recycled in situ 10 times without any significant loss of the catalyst activity. In addition, this novel strategy was also extended to other hydrophobic monomers such as styrene, methyl acrylate and tert-butyl acrylate, indicating a versatile method for iron catalysis, separation and recycling.

Thermoregulated phase transfer catalysis in aqueous/organic biphasic system: facile and highly efficient ATRP catalyst separation and recycling in situ using typical alkyl halide as initiator

Co-reporter:Xiaowu Jiang, Yanjing Luo, Zhen Li, Lifen Zhang, Zhenping Cheng and Xiulin Zhu

Polymer Chemistry 2015 vol. 6(Issue 35) pp:6394-6401

Publication Date(Web):23 Jul 2015

DOI:10.1039/C5PY00953G

Developing a highly efficient and facile method for catalyst separation and recycling from an ATRP system facilitates wide application of atom transfer radical polymerization (ATRP). In this work, an important development of thermoregulated phase transfer catalysis (TRPTC)-based initiators for continuous activator regeneration (ICAR) ATRP for transition metal catalyst separation and recycling in a water/p-xylene biphasic system was achieved using alkyl halide (ethyl-2-bromo-2-phenyl acetate, EBPA) as the initiator for the first time. Herein, poly(poly(ethylene glycol) methyl ether methacrylate)-supported dipicolylamine (PPEGMA-BPMA) was designed as the thermoregulated ligand, CuBr2 as the catalyst, 1,1′-azobis(cyclohexanecarbonitrile) (ACHN) as the azo-initiator and methyl methacrylate (MMA) as the model monomer, respectively. The polymerization kinetics was investigated in detail, and the “living” feature of this novel polymerization system was confirmed by chain-end analysis and chain extension experiments for the resultant PMMA. It is noted that the catalyst complex (PPEGMA-BPMA/CuBr2) existed only in an aqueous phase at room temperature, and it transferred to an organic phase and subsequently catalyzed the ICAR ATRP of MMA when the temperature increased to 90 °C. After polymerization the catalyst complex successfully transferred to the aqueous phase almost completely from the organic phase again while the resultant PMMA existed in the p-xylene phase once the temperature cooled down to room temperature. Therefore, the process described above combined the advantages of homogeneous catalysis in the organic phase and heterogeneous catalyst separation in situ in the aqueous/organic biphasic phase system by just changing the reaction temperature. Importantly, the catalyst complex in the aqueous phase could be recycled easily, and the catalyst retained high catalytic activity even after eight recycling times.

Fast RAFT aqueous polymerization in a continuous tubular reactor: consecutive synthesis of a double hydrophilic block copolymer

Co-reporter:Zhen Li, Weijie Chen, Lifen Zhang, Zhenping Cheng and Xiulin Zhu

Polymer Chemistry 2015 vol. 6(Issue 28) pp:5030-5035

Publication Date(Web):19 Jun 2015

DOI:10.1039/C5PY00847F

In this work, double hydrophilic diblock copolymer poly(3-sulfopropyl methacrylate potassium salt)-b-poly(poly(ethylene glycol) methyl ether methacrylate) (PSPMA-b-PPEGMA) was successfully synthesized via a fast reversible addition–fragmentation chain transfer (RAFT) polymerization at 70 °C in a continuous tubular reactor in water without handling the intermediate macro-RAFT agent. An extremely high conversion was reached in a relatively short time (less than 2 h). 4-Cyano-4-(thiobenzoylthio)pentanoic acid (CTBCOOH) was used as the chain transfer agent and 2,2′-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (AIBI) was used as the initiator. Typical “living”/controlled characteristics of the polymerization system were demonstrated: first-order polymerization kinetics, a linear increase in the molecular weight with monomer conversion, and a narrow molecular weight distribution for the resultant polymer. 1H NMR spectroscopy and chain-extension experiments confirmed the attachment and “livingness” of the RAFT terminal group in the obtained polymer chain ends.

A novel methacrylate with a bisphosphonate group: RAFT polymerization and flame retardant property of the resultant polymers

Co-reporter:Tianchi Xu, Lifen Zhang, Zhenping Cheng and Xiulin Zhu

Polymer Chemistry 2015 vol. 6(Issue 12) pp:2283-2289

Publication Date(Web):14 Jan 2015

DOI:10.1039/C4PY01647E

A number of phosphorus-based monomers have been evaluated by free radical polymerization or photopolymerization, but fewer examples have been involved in the “living”/controlled radical polymerization (LRP) of such type of monomers, whereas LRP techniques allow the synthesis of well-defined polymers with designable structures, compositions and properties. In this work, a novel methacrylate based monomer with a bisphosphonate group 4-(bis(diethoxyphosphoryl)methyl)phenyl methacrylate (BPMA) was synthesized first and then polymerized by reversible addition-fragmentation chain transfer (RAFT) polymerization. The polymerization showed typical “living” features such as the polymerization, which indicates first order kinetics with respect to monomer concentration, and the molecular weights of the resultant polymers increase with monomer conversion. Furthermore, the resultant polymers demonstrated better thermal and flame-retardant properties. According to the thermal gravimetric analyzer (TGA) test, the amount of residual carbonaceous mass (char) increased with the molecular weight of the resultant polymers. Furthermore, the micro-scale combustion calorimetry (MCC) test also confirmed its superior flame-retardant performance.

A surfactant-free emulsion RAFT polymerization of methyl methacrylate in a continuous tubular reactor

Co-reporter:Zhen Li, Weijie Chen, Zhengbiao Zhang, Lifen Zhang, Zhenping Cheng and Xiulin Zhu

Polymer Chemistry 2015 vol. 6(Issue 11) pp:1937-1943

Publication Date(Web):23 Dec 2014

DOI:10.1039/C4PY01456A

In this work, a surfactant-free emulsion RAFT polymerization of methyl methacrylate (MMA) without any hydrophilic macro-RAFT agent was successfully carried out in a continuous tubular flow reactor with a mixed solvent of water and dimethyl formamide (DMF), which allowed the system to form an emulsion in situ, using 4-cyano-4-(thiobenzoylthio)pentanoic acid (CTBCOOH) as the chain transfer agent and emulsion stabilizer under the synergistic effect of sodium hydroxide (NaOH), and 2,2′-azobisisobutyronitrile (AIBN) as the initiator. The resulting latexes showed good stability and the polymerization demonstrated typical “living”/controlled characteristics of RAFT polymerization: first-order kinetics, linear increase of molecular weights with monomer conversion and narrow molecular weight distributions for the resulting PMMA. NMR spectroscopy and chain-extension experiments confirmed the attachment and livingness of the RAFT terminal group in the obtained polymer chain ends.

Diffusion-Regulated Phase-Transfer Catalysis for Atom Transfer Radical Polymerization of Methyl Methacrylate in an Aqueous/Organic Biphasic System

Co-reporter:Mingqiang Ding;Xiaowu Jiang;Jinying Peng;Zhenping Cheng;Xiulin Zhu

Macromolecular Rapid Communications 2015 Volume 36( Issue 6) pp:538-546

Publication Date(Web):

DOI:10.1002/marc.201400639

Recent Progress on Transition Metal Catalyst Separation and Recycling in ATRP

Co-reporter:Mingqiang Ding;Xiaowu Jiang;Zhenping Cheng;Xiulin Zhu

Macromolecular Rapid Communications 2015 Volume 36( Issue 19) pp:1702-1721

Publication Date(Web):

DOI:10.1002/marc.201500085

Facile and universal photo-induced living radical polymerization system mediated by iniferter agent and copper(II) acetate at ambient temperature

Co-reporter:Liangfang Fan, Hongjuan Jiang, Lifen Zhang, Zhenping Cheng and Xiulin Zhu

RSC Advances 2015 vol. 5(Issue 40) pp:31657-31663

Publication Date(Web):27 Mar 2015

DOI:10.1039/C5RA03264D

A facile and universal photo-induced living radical polymerization system suitable for various types of monomers, such as oil-soluble methyl methacrylate (MMA), n-butyl acrylate (n-BA) and styrene (St) as well as water-soluble poly(ethylene glycol) monomethyl ether methacrylate (PEGMA) and 2-(dimethylamino)ethyl methacrylate (DMAEMA), was successfully developed with iniferter agent 1-cyano-1-methylethyl diethyldithiocarbamate (MANDC) and organic catalyst copper(II) acetate (Cu(OAc)2) under UV irradiation at ambient temperature. The polymerization kinetics with different molar ratios ([MMA]0/[MANDC]0/[Cu(OAc)2]0 = 500/1/x (x = 0.1 (200 ppm), 0.01 (20 ppm), 0.0025 (5 ppm))) indicated that the novel polymerization system showed typical “living”/controlled radical polymerization features, indicated by a linear increase of molecular weights with monomer conversion while keeping relatively narrow molecular weight distributions (Mw/Mn = 1.19–1.45) for the resultant polymers. Even when the amount of Cu(OAc)2 was minimized to only 1 ppm level, the polymerization system still showed living character. The living features of the obtained polymers were further confirmed by a successful chain-extension experiment. In addition, a possible polymerization mechanism was discussed in this work.

Iron-mediated AGET ATRP with crown ether as both ligand and solvent

Co-reporter:Jinying Peng, Mingqiang Ding, Zhenping Cheng, Lifen Zhang and Xiulin Zhu

RSC Advances 2015 vol. 5(Issue 127) pp:104733-104739

Publication Date(Web):26 Nov 2015

DOI:10.1039/C5RA20480A

It is well known that crown ethers can selectively complex with metal ions due to their unique structure, and they have been widely used as an ion carrier and in phase-transfer catalysis in organic synthesis. In this work, crown ethers such as 18-crown-6 or 15-crown-5 were introduced into an iron-mediated AGET ATRP (Activators Generated by Electron Transfer for Atom Transfer Radical Polymerization) system as both ligand and solvent for the first time. Herein, FeCl3·6H2O was used as the catalyst, ethyl alpha-bromophenylacetate (EBPA) as the initiator, Na2S2O4 as the reducing agent, and methyl methacrylate (MMA) as the model monomer, and then the method was extended to styrene (St), acrylonitrile (AN) and tert-butyl acrylate (t-BA), without any additional ligands. The effect of various factors, such as the type of reducing agents, the amounts of 18-crown-6, and polymerization temperatures (60–90 °C) on the polymerization were investigated. Furthermore, the polymerization kinetics revealed the typical “living” features of this polymerization system. For example, the molecular weights of PMMA increased linearly with the monomer conversion while maintaining a relatively low molecular weight distribution (Mw/Mn < 1.31). As well as this, the “living” feature of this polymerization system was further confirmed by chain-end analysis (1H NMR, MALDI-TOF) and chain extension experiments.

Reversible addition-fragmentation chain transfer polymerization of vinyl acetate under high pressure

Co-reporter:Jing Chen;Xiaoning Zhao;Zhenping Cheng;Xiulin Zhu

Journal of Polymer Science Part A: Polymer Chemistry 2015 Volume 53( Issue 12) pp:1430-1436

Publication Date(Web):

DOI:10.1002/pola.27582

ABSTRACT

In this work, high molecular weight polyvinyl acetate (PVAc) (M_n,GPC = 123,000 g/mol, M_w/M_n = 1.28) was synthesized by reversible addition-fragmentation chain transfer polymerization (RAFT) under high pressure (5 kbar), using benzoyl peroxide and N,N-dimethylaniline as initiator mediated by (S)-2-(ethyl propionate)-(O-ethyl xanthate) (X1) at 35 °C. Polymerization kinetic study with RAFT agent showed pseudo-first order kinetics. Additionally, the polymerization rate of VAc under high pressure increased greatly than that under atmospheric pressure. The “living” feature of the resultant PVAc was confirmed by ¹H NMR spectroscopy and chain extension experiments. Well-defined PVAc with high molecular weight and narrow molecular weight distribution can be obtained relatively fast by using RAFT polymerization at 5 kbar. © 2015 Wiley Periodicals, Inc. J. Polym. Sci. Part A: Polym. Chem. 2015, 53, 1430–1436

Bulk AGET ATRP of methyl methacrylate using iron(III) acetylacetonate as a catalyst

Co-reporter:Yuan Liu, Tianchi Xu, Lifen Zhang, Zhenping Cheng and Xiulin Zhu

Polymer Chemistry 2014 vol. 5(Issue 23) pp:6804-6810

Publication Date(Web):13 Aug 2014

DOI:10.1039/C4PY00968A

In this work, polymerization of methyl methacrylate (MMA) was successfully conducted by atom transfer radical polymerization with activators generated by electron transfer (AGET ATRP) at 90 °C, using iron(III) acetylacetonate (Fe(acac)3) as a catalyst, ethyl alpha-bromophenylacetate (EBPA) as an initiator, ascorbic acid (AsAc) as a reducing agent and triphenyl phosphine (PPh3) as a ligand. The polymerization kinetics showed that the polymerization rate (the conversion reached up to 98.1% after 60 min) was much higher than that mediated by inorganic iron salts and it was affected by the feed of the iron catalyst. Moreover, the kinetic plots were linear, and the molecular weights of the resulting polymers with molecular weight distribution around 1.2, increased linearly with monomer conversions, indicating good features of “living”/controlled radical polymerizations. The end-functionality of the polymers was confirmed by 1H NMR spectroscopy and a chain extension experiment.

Living cationic polymerization of bisazobenzene-containing vinyl ether and synthesis of a graft copolymer by combination with ATRP

Co-reporter:Ming Li, Lifen Zhang, Meixia Tao, Zhenping Cheng and Xiulin Zhu

Polymer Chemistry 2014 vol. 5(Issue 13) pp:4076-4082

Publication Date(Web):14 Mar 2014

DOI:10.1039/C4PY00162A

Cationic polymerizable bisazobenzene-containing vinyl ether, which is being referred to as VEBiB, was synthesized and its cationic copolymerization with isobutyl vinyl ether (IBVE) using Et1.5AlCl1.5 as the catalyst, ethyl acetate as the added base, and 1-isobutoxyethyl acetate (IBEA) as the initiator was investigated at 0 °C. The copolymerization showed living features, which was confirmed by the linear increase of the molecular weight of the obtained copolymer with monomer conversion and relatively narrow molecular weight distribution. Furthermore, the resultant copolymer could be used as a macroinitiator for the atom transfer radical polymerization with activators generated by electron transfer (AGET ATRP) of methyl methacrylates (MMA) due to the presence of ATRP initiator moieties in the side chains of PVEBiB. A well defined graft copolymer was obtained and its photoresponsive behaviors were studied using UV-vis spectroscopy.

Cu(II)-Mediated Atom Transfer Radical Polymerization of Methyl Methacrylate via a Strategy of Thermo-Regulated Phase-Separable Catalysis in a Liquid/Liquid Biphasic System: Homogeneous Catalysis, Facile Heterogeneous Separation, and Recycling

Co-reporter:Jinlong Pan;Bingjie Zhang;Xiaowu Jiang;Zhenping Cheng;Xiulin Zhu

Macromolecular Rapid Communications 2014 Volume 35( Issue 18) pp:1615-1621

Publication Date(Web):

DOI:10.1002/marc.201400277

Photo-induced living cationic copolymerization of isobutyl vinyl ether and vinyl ether with carbazolyl groups

Co-reporter:Ming Li;Li-fen Zhang 张丽芬;Mei-xia Tao

Chinese Journal of Polymer Science 2014 Volume 32( Issue 11) pp:1564-1574

Publication Date(Web):2014 November

DOI:10.1007/s10118-014-1540-8

In this work, a fluorescent monomer 2-(9-carbazolyl) ethyl vinyl ether (CEVE) was synthesized in our lab, and its photo-induced living cationic copolymerization behavior with isobutyl vinyl ether (IBVE) was investigated in detail using diphenyliodonium chloride (DPICl)/2,2-dimethoxy-2-phenylacetophenone (DMPA) and zinc bromide (ZnBr2) initiating system in dichloromethane solution at 5 °C, −5 °C, and −15 °C, respectively. The living nature of this copolymerization system was confirmed by adding fresh comonomer method after the copolymerization almost finished. In addition, the obtained fluorescent copolymer poly(IBVE-co-CEVE) has a low glass transition temperature (Tg), below −10 °C.

Iron-mediated (dual) concurrent ATRP–RAFT polymerization of water-soluble poly(ethylene glycol) monomethyl ether methacrylate

Co-reporter:Jinlong Pan, Jie Miao, Lifen Zhang, Zhangyong Si, Changwen Zhang, Zhenping Cheng and Xiulin Zhu

Polymer Chemistry 2013 vol. 4(Issue 23) pp:5664-5670

Publication Date(Web):01 Jul 2013

DOI:10.1039/C3PY00671A

In this work, the iron-mediated (dual) concurrent ATRP–RAFT polymerization of water-soluble poly(ethylene glycol) monomethyl ether methacrylate (PEGMA) was investigated at different polymerization temperatures (from 90 °C to 30 °C), using 2-cyanoprop-2-yl-1-dithionaphthalate (CPDN) as an alkyl pseudohalide initiator, ethyl 2-bromoisobutyrate (EBiB) as a co-initiator, and FeCl3·6H2O/PPh3 complex as the catalyst. The polymerization kinetics was studied in detail at polymerization temperatures of 90 °C and 30 °C. The results showed that the concurrent ATRP–RAFT polymerization (using only CPDN as the initiator) of PEGMA could be carried out successfully, even if the polymerization temperature was reduced to 30 °C. Furthermore, the polymerization rate was remarkably enhanced via dual concurrent ATRP–RAFT polymerization (using CPDN and EBiB as co-initiators). For example, the monomer conversion could be higher than 70% in the dual concurrent ATRP–RAFT polymerization system in 65.5 h, while a conversion of only 22% could be obtained after 167 h for the concurrent ATRP–RAFT polymerization system at 30 °C. The “living” features of dual concurrent ATRP–RAFT polymerization of PEGMA were verified by chain end analysis and chain-extension experiments.

Facile Iron-Mediated Dispersant-Free Suspension Polymerization of Methyl Methacrylate via Reverse ATRP in Water

Co-reporter:Jun Cao;Xiaowu Jiang;Chun Tian;Xiaoning Zhao;Qi Ke;Xiangqiang Pan;Zhenping Cheng;Xiulin Zhu

Macromolecular Rapid Communications 2013 Volume 34( Issue 22) pp:1747-1754

Publication Date(Web):

DOI:10.1002/marc.201300513

Fabrication of magnetic nanofibers via surface-initiated RAFT polymerization and coaxial electrospinning

Co-reporter:Shaogan Niu, Lifen Zhang, Nan Wang, Jian Zhu, Wei Zhang, Zhenping Cheng, Xiulin Zhu

Reactive and Functional Polymers 2013 73(11) pp: 1447-1454

Publication Date(Web):November 2013

DOI:10.1016/j.reactfunctpolym.2013.07.011

Synthesis of well-defined copolymer of acrylonitrile and maleic anhydride via RAFT polymerization

Co-reporter:Shaogan Niu;Mingqiang Ding;Mengting Chen;Ting Feng;Liang Wei;Zhenping Cheng ;Xiulin Zhu

Journal of Polymer Science Part A: Polymer Chemistry 2013 Volume 51( Issue 24) pp:5263-5269

Publication Date(Web):

DOI:10.1002/pola.26956

ABSTRACT

Well-defined copolymer of acrylonitrile (AN) and maleic anhydride (MAn) has been successfully synthesized via reversible addition-fragmentation chain transfer polymerization. The polymerization kinetics and “living”/controlled features were thoroughly studied and confirmed. The thermal properties and spinnability of the prepared copolymers were investigated via differential scanning calorimetry, thermogravimetric analyzer, and electrospinning subsequently. When PAN-co-PMAn was used as precursors, nonwoven with “crosslinked” structures was obtained during electrospinning. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 5263–5269

Facile Soap-Free Miniemulsion Polymerization of Methyl Methacrylate via Reverse Atom Transfer Radical Polymerization

Co-reporter:Gaohua Zhu;Xiangqiang Pan;Wei Zhang;Zhenping Cheng;Xiulin Zhu

Macromolecular Rapid Communications 2012 Volume 33( Issue 24) pp:2121-2126

Publication Date(Web):

DOI:10.1002/marc.201200492

Abstract

A facile soap-free miniemulsion polymerization of methyl methacrylate (MMA) was successfully carried out via a reverse ATRP technique, using a water-soluble potassium persulfate (KPS) or 2,2′-azobis(2-methylpropionamidine) dihydrochloride (V-50) both as the initiator and the stabilizer, and using an oil-soluble N,N-n-butyldithiocarbamate copper (Cu(S₂CN(C₄H₉)₂)₂) as the catalyst without adding any additional ligand. Polymerization results demonstrated the “living”/controlled characteristics of ATRP and the resultant latexes showed good colloidal stability with average particle size around 300–700 nm in diameter. The monomer droplet nucleation mechanism was proposed. NMR spectroscopy and chain-extension experiments under UV light irradiation confirmed the attachment and livingness of UV light sensitive SC(S)N(C₄H₉)₂ group in the chain end.

Controlled Bimodal Molecular-Weight-Distribution Polymers: Facile Synthesis by RAFT Polymerization

Co-reporter:Jian Qin;Dr. Lifen Zhang;Hongjuan Jiang;Dr. Jian Zhu;Dr. Zhengbiao Zhang;Dr. Wei Zhang;Dr. Nianchen Zhou;Dr. Zhenping Cheng;Dr. Xiulin Zhu

Chemistry - A European Journal 2012 Volume 18( Issue 19) pp:6015-6021

Publication Date(Web):

DOI:10.1002/chem.201103914

Abstract

The RAFT agents RAFT-1 and RAFT-2 were used for RAFT polymerization to synthesize well-defined bimodal molecular-weight-distribution (MWD) polymers. The system showed excellent controllability and “living” characteristics toward both the higher- and lower-molecular-weight fractions. It is important that bimodal higher-molecular-weight (HMW) polymers and block copolymers with both well-controlled molecular weight (MW) and MWD could be prepared easily due to the “living” features of RAFT polymerization. The strategy realized a mixture of higher/lower-molecular-weight polymers at the molecular level but also preserved the features of living radical polymerization (LRP) of the RAFT polymerization.

A Highly Efficient Iron-Mediated AGET ATRP of Methyl Methacrylate Using Fe(0) Powder as the Reducing Agent

Co-reporter:Jian Qin;Zhenping Cheng;Zhengbiao Zhang;Jian Zhu ;Xiulin Zhu

Macromolecular Chemistry and Physics 2011 Volume 212( Issue 10) pp:999-1006

Publication Date(Web):

DOI:10.1002/macp.201000737

Modification of SEBS rubber via iron-mediated AGET ATRP in the presence of limited amounts of air

Co-reporter:Wei Xu, Zhenping Cheng, Zhengbiao Zhang, Lifen Zhang, Xiulin Zhu

Reactive and Functional Polymers 2011 71(6) pp: 634-640

Publication Date(Web):June 2011

DOI:10.1016/j.reactfunctpolym.2011.03.008

Real-time monitoring of a controlled drug delivery system in vivo: construction of a near infrared fluorescence monomer conjugated with pH-responsive polymeric micelles

Co-reporter:Li Chen, Bizheng Chen, Xiaodong Liu, Yujie Xu, Lifen Zhang, Zhenping Cheng and Xiulin Zhu