Polymer Chemistry
·
2016
·Vol. 7
·期 22
·3756-3765
·
IF 5.687
Mingguang Yu,Jianbo Tan,Jianwen Yang,Zhaohua Zeng
In a common RAFT dispersion polymerization induced self-assembly (PISA) formulation, R-type macro-RAFT agents with a solvophilic chain attached at the leaving group side are normally used to mediate the polymerization, meanwhile Z-type macro-RAFT agents with a solvophilic chain attached at the Z-group side are seldom employed. In this paper, we have tried to use a Z-type macro-RAFT agent (mPEG113-BTPA) to mediate RAFT dispersion polymerization of styrene, and found that the process exhibited a poorer PISA tendency and weaker molecular weight control. In comparison, we have conducted the same process mediated with an R-type macro-RAFT agent (mPEG113-DDMAT), and found that the formulation exhibited a typical PISA process, and nanoparticles were produced in situ. Further experiments suggest that the location of RAFT groups plays a key role for the PISA process in RAFT dispersion polymerization. The RAFT groups will be embedded in the produced particles when an R-type macro-RAFT agent is employed, but locate on the particle surface in the case of the Z-type macro-RAFT agent. We have tried to employ the RAFT groups on the surface of the mPEG113-BTPA stabilized particles to modify the particle surface, and successfully removed the solvophilic block via breaking the RAFT group, and generated the poly(dimethylacrylamide) block by surface-initiated RAFT polymerization. Based on the above mechanism perspective, we have designed a preliminary experiment, and found that well-defined monodisperse nanospheres could be prepared by heterogeneous RAFT dispersion polymerization mediated with a Z-type macro-RAFT agent-based block copolymer which was synthesized via pre-polymerization of styrene in 1,4-dioxane mediated with mPEG113-BTPA.
研究领域:
高分子化学
·
胶体与界面科学
·
纳米材料
·
可控自由基聚合
·
自组装
·
药物递送系统
✓ 已验证
DOI
高影响因子
Journal of Macromolecular Science Part A-Pure and Applied Chemistry
·
2020
·
IF 1.349
Jia Liu,Jian Li,Chen Yi Wang,Qiang Ren
The effect of the hydrophobicity of block copolymer macro-RAFT agents on the controllability of RAFT surfactant-free cationic emulsion polymerization of styrene was investigated. Three different copolymers, poly(dimethyl aminoethyl acrylate) (PDMAEA), poly(dimethyl aminoethyl acrylate-co-styrene)-b-(butyl acrylate) (P(DMAEA-co-St)-b-PBA) and poly(dimethyl aminoethyl acrylate-co-styrene)-b-(hexafluorobutyl acrylate) (P(DMAEA-co-St)-b-PHFBA), which had different hydrophobicity in their hydrophobic segments, were synthesized and used as the macro-RAFT agents. When P(DMAEA-co-St)-b-PHFBA and P(DMAEA-co-St)-b-PBA were used as macro-RAFT agents, the RAFT surfactant-free cationic emulsion polymerization of styrene underwent very fast. But when the PDMAEA was used as the macro-RAFT agent, no polymerization of styrene was observed. The controllability of styrene polymerization with P(DMAEA-co-St)-b-PHFBA as the RAFT agent showed much better than that with P(DMAEA-co-St)-b-PBA as the macro RAFT agent. This was ascribed to hydrophobicity difference of the hydrophobic segment between P(DMAEA-co-St)-b-PHFBA and P(DMAEA-co-St)-b-PBA macro-RAFT agents. A mechanism explanation for the controllability of emulsion polymerization was proposed. The location of the active trithiocarbonate group of the macro-RAFT agent in micelle was supposed to be a key factor affecting the controllability of RAFT surfactant-free cationic emulsion polymerization of styrene. The hydrophobicity of the RAFT agent and nature of medium had impact on the location of the active trithiocarbonate group of the macro-RAFT agent in micelle and affected the polymerization controllability.
研究领域:
高分子化学
·
材料科学
·
化学工程
·
胶体与界面科学
✓ 已验证
DOI
高影响因子
MACROMOLECULES
·
2013
·
IF 5.521
Jianbo Tan,Xin Rao,Jianwen Yang,Zhaohua Zeng
Highly monodisperse PMMA microspheres have been synthesized by photoinitiated RAFT dispersion polymerization in the presence of a Macro-RAFT agent and a small molecular RAFT agent. A particle yield of over 90% was achieved within 3 h under UV irradiation at room temperature. The Macro-RAFT agent acts as a stabilizer and stabilizes the particles via formation of block copolymers in situ, and XPS analysis shows that about 29.9% of the particle surface was covered by the stabilizer. Various surface functional microspheres were prepared by using four kinds of Macro-RAFT agents, including poly(methoxy poly(ethylene glycol) acrylate)-based trithiocarbonate (P(mPEGA)-TTC), poly(methoxy poly(ethylene glycol) acrylate-co-acrylic acid)-based trithiocarbonate (P(mPEGA-co-AA)-TTC), poly(acrylic acid)-based trithiocarbonate (PAA-TTC), and poly(methoxy poly(ethylene glycol) acrylate-co-4-vinylpyridine)-based trithiocarbonate (P(mPEGA-co-4VP)-TTC). Ag/PMMA nanocomposite spheres were prepared using the P(mPEGA-co-AA)-TTC stabilized microspheres. The PAA-TTC stabilized microspheres showed pH sensitivity. The colloidal stability of the particles prepared by this photoinitiated RAFT dispersion polymerization was also investigated.
研究领域:
高分子化学
·
材料科学
·
纳米技术
·
胶体与界面科学
✓ 已验证
产品关联
DOI
高影响因子
Polymer Chemistry
·
2019
·Vol. 10
·期 9
·1150-1157
·
IF 4.76
Shuwen Qu,Ke Wang,Habib Khan,Weifeng Xiong,Wangqing Zhang
Block copolymer nano-assemblies were synthesized via initiators for continuous activator regeneration atom transfer radical polymerization (ICAR ATRP) dispersion polymerization employing the CuBr2/tris(2-pyridylmethyl)amine catalyst in an alcoholic solvent at a relatively low temperature of 45 °C. The typical poly(ethylene glycol)-block-polystyrene (PEG-b-PS) nano-assemblies synthesized via ICAR ATRP dispersion polymerization are compared with those synthesized via RAFT dispersion polymerization under other similar conditions. It is found that the PEG45-b-PS nano-assemblies, e.g., including lamellas, vesicles and vesicular clusters, synthesized via ICAR ATRP dispersion polymerization have very complicated morphologies, which are different from those synthesized via RAFT dispersion polymerization. The reasons leading to the differences are investigated, and it is conclusively supposed that the high Đ of the synthesized BCPs and the salt of the copper catalyst used in ICAR ATRP dispersion polymerization should be involved. This low temperature initiated ICAR ATRP dispersion polymerization is believed to be a valid method to prepare block copolymer nano-assemblies through polymerization-induced self-assembly.
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
MOLECULES
·
2024
·Vol. 29
·期 6
·1217
·
IF 4.2
Jingkai Nie,Hang Yin,Ruyue Cao,Changyuan Huang,Xiang Luo,Jun Ji
This paper developed a method for preparing ultrasound-responsive microgels based on reversible addition fragmentation chain transfer-hetero Diels–Alder (RAFT-HAD) dynamic covalent bonding. First, a styrene cross-linked network was successfully prepared by a Diels–Alder (DA) reaction between phosphoryl dithioester and furan using double-ended diethoxyphosphoryl dithiocarbonate (BDEPDF) for RAFT reagent-mediated styrene (St) polymerization, with a double-ended dienophile linker and copolymer of furfuryl methacrylate (FMA) and St as the dienophile. Subsequently, the microgel system was constructed by the HDA reaction between phosphoryl disulfide and furan groups using the copolymer of polyethylene glycol monomethyl ether acrylate (OEGMA) and FMA as the dienophore building block and hydrophilic segment and the polystyrene pro-dienophile linker as the cross-linker and hydrophobic segment. The number of furans in the dienophile chain and the length of the dienophile linker were regulated by RAFT polymerization to investigate the effects of the single-molecule chain functional group degree, furan/dithioester ratio, and hydrophobic cross-linker length on the microgel system. The prepared microgels can achieve the reversible transformation of materials under force responsiveness, and their preparation steps are simple and adaptive to various potential applications in biomedical materials and adaptive electrical materials.
研究领域:
材料科学
·
生物医学工程
·
高分子化学
✓ 已验证
DOI
高影响因子
CHINESE JOURNAL OF POLYMER SCIENCE
·
2021
·Vol. 39
·期 9
·1138-1145
·
IF 3.603
Li Ruo-Yu,An Ze-Sheng
Photoenzymatic reversible addition-fragmenatation chain transfer (RAFT) emulsion polymerization, surfactant-free or ab initio, of various monomers is reported with oxygen tolerance. In surfactant-free emulsion polymerizatoin, poly( N, N -dimethylacrylamide)s were used as stabilizer blocks for emulsion polymerization of methyl acrylate, n-butyl acrylate and styrene, producing well-defined amphiphilic block copolymers, including those with an ultrahigh molecular weight, at quantitative conversions. The controlled character of surfactant-free emulsion polymerization was confirmed by kinetic studies, chain extension studies and GPC analyses. Temporal control was demonstrated by light ON/OFF experiments. In ab initio emulsion polymerization of methyl acrylate and methyl methacrylate, low-dispersity hydrophobic polymers were synthesized with predictable molecular weights. This study extends the monomer scope suitable for photoenzymatic RAFT polymerization from hydrophilic to hydrophobic monomers and demonstrates that oxygen-tolerance can be equally achieved for emulsion polymerization with excellent RAFT control.
研究领域:
高分子化学
·
材料科学
✓ 已验证
DOI
高影响因子
ANALYTICAL CHEMISTRY
·
2021
·
IF 6.986
Qiong Hu,Luofeng Su,Zhuohua Chen,Yanyu Huang,Dongdong Qin,Li Niu
Trypsin is a key proteolytic enzyme in the digestive system and its abnormal levels are indicative of some pancreatic diseases. Taking advantage of the coenzyme-mediated electrografting of ferrocenyl polymers as a novel strategy for signal amplification, herein, a signal-on cleavage-based electrochemical biosensor is reported for the highly selective interrogation of trypsin activity at ultralow levels. The construction of the trypsin biosensor involves (i) the immobilization of peptide substrates (without free carboxyl groups) via the N-terminus, (ii) the tryptic cleavage of peptide substrates, (iii) the site-specific labeling of the reversible addition–fragmentation chain transfer (RAFT) agents, and (iv) the grafting of ferrocenyl polymers through the electro-RAFT (eRAFT) polymerization, which is mediated by potentiostatic reduction of nicotinamide adenine dinucleotide (NAD+) coenzymes. Through the NAD+-mediated eRAFT (NAD+-eRAFT) polymerization of ferrocenylmethyl methacrylate (FcMMA), the presence of a few tryptic cleavage events can eventually result in the recruitment of a considerable amount of ferrocene redox tags. Obviously, the NAD+-eRAFT polymerization is low-cost and easy to operate as a highly efficient strategy for signal amplification. As expected, the as-constructed biosensor is highly selective and sensitive toward the signal-on interrogation of trypsin activity. Under optimal conditions, the detection limit can be as low as 18.2 μU/mL (∼72.8 pg/mL). The results also demonstrate that the as-constructed electrochemical trypsin biosensor is applicable to inhibitor screening and the interrogation of enzyme activity in the presence of complex sample matrices. Moreover, it is low-cost, less susceptible to false-positive results, and relatively easy to fabricate, thus holding great potential in diagnostic and therapeutic applications.
研究领域:
分析化学
·
生物化学
·
生物技术
·
电化学
·
酶学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
EUROPEAN POLYMER JOURNAL
·
2018
·
IF 3.741
Xi Chen,Xiaojun Liu,Congcong Miao,Pengfei Song,Yubing Xiong
Inimer bears a polymerizable vinyl group and a reactable group, and thus has great potentials in the synthesis of branched and functional polymers. Herein, a strategy was developed for the synthesis of ionic liquid (IL)-like inimer containing a trithiocarbonate moiety and a styryl group. The newly-developed IL-like inimer could be facilely achieved via the neutralization reaction using a carboxyl-contained chain transfer agent (CTA) and an alkaline IL monomer. The IL-like inimer was characterized through proton and carbon nuclear magnetic resonance spectroscopy ( 1 H and 13 C NMR), Flourier transform infrared spectroscopy (FT-IR) and Mass spectroscopy. Moreover, the reversible addition-fragmentation chain transfer (RAFT) polymerization of N-isopropylacrylamide (NIPAM) mediated by the as-prepared IL-like inimer was investigated. The results revealed that branched PNIPAM with tunable molecular weight and degree of branching (DB) could be prepared. Additionally, lower critical solution temperature (LCST) of branched PNIPAM could be adjusted through the feed ratio of IL-like inimer and the monomer in the polymerization process. As a result, our study offers a new technique for the design of functional inimer, as well as broadens the application of ILs in the polymer field.
研究领域:
高分子化学
·
材料科学
✓ 已验证
DOI
高影响因子
Materials Science & Engineering C-Materials for Biological Applications
·
2017
·
IF 4.164
Yingge Shi,Guanjian Zeng,Dazhuang Xu,Meiying Liu,Ke Wang,Zhen Li,Lihua Fu,Qingsong Zhang,Xiaoyong Zhang,Yen Wei
Carbon nanotubes (CNTs) are a type of one-dimensional carbon nanomaterials that possess excellent physicochemical properties and have been potentially utilized for a variety of applications. Surface modification of CNTs with polymers is a general route to expand and improve the performance of CNTs and has attracted great research interest over the past few decades. Although many methods have been developed previously, most of these methods still showed some disadvantages, such as low efficiency, complex experimental procedure and harsh reaction conditions etc. In this work, we reported a practical and novel way to fabricate CNTs based polymer composites via the combination of mussel inspired chemistry and reversible addition fragmentation chain transfer (RAFT) polymerization. First, the amino group was introduced onto the surface of CNTs via self-polymerization of dopamine. Then, chain transfer agent can be immobilized on the amino groups functionalized CNTs to obtain CNT-PDA-CTA, which can be utilized for surface-initiated RAFT polymerization. A water soluble and biocompatible monomer poly(ethylene glycol) monomethyl ether methacrylate (PEGMA) was adopted to fabricate pPEGMA functionalized CNTs through RAFT polymerization. The successful preparation of CNTs based polymer composites (CNT-pPEGMA) was confirmed by transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis and X-ray photoelectron spectroscopy in details. The CNT-pPEGMA showed good dispersibility and desirable biocompatibility, making them highly potential for biomedical applications. More importantly, a large number of CNTs based polymer composites could also be fabricated through the same strategy when different monomers were used due to the good monomer adaptability of RAFT polymerization. Therefore, this strategy should be a general method for preparation of various multifunctional CNTs based polymer composites.
研究领域:
材料科学
·
生物医学工程
✓ 已验证
DOI
高影响因子
Polymer Chemistry
·
2021
·Vol. 12
·期 34
·4974-4985
·
IF 5.582
Yuejia Zhu,Luoyu Gao,Zhenjiang Li,Bo Liu,Zhihao Zhang,Haoying Tong,Yuanyuan Qu,Yusheng Quan,Xin Zou,Kai Guo
Olefin monomers are divided into cationically polymerizable ones (monomer A, such as vinyl ethers) and radically polymerizable ones (monomer B, such as acrylates); in parallel, cyclic ester monomers are polymerizable either electrophilically (monomer C, such as lactones) or nucleophilically (monomer D, such as lactides). To address the challenge of polymerizing the distinctive four types of monomers in one pot into ABCD type tetrablock copolymers, we proposed a bifunctional reversible addition–fragmentation chain transfer (RAFT) agent bearing both the RAFT polymerization site and ring-opening polymerization (ROP) site. The RAFT site was able to copolymerize A and B via switching the cationic RAFT polymerization (cRAFT) to radical RAFT polymerization (rRAFT). Subsequently, the ROP site copolymerized C and D by switching the electrophilic ROP to nucleophilic ROP. A general dual-switch strategy of both RAFT and ROP mechanism transitions successfully produced ABCD-type tetrablock quaterpolymers in one pot by sequential monomer feeding. Poly(isobutyl vinyl ether)-b-poly(methyl methacrylate)-b-poly(δ-valerolactone)-b-polylactide (PIBVE-b-PMMA-b-PVL-b-PLA) was synthesized. All synthesized homopolymers and multi-block copolymers exhibited predicted molecular weights and relatively narrow dispersities (Đ ≤ 1.45). The copolymerization strategy paved a new avenue to combine cRAFT, rRAFT and ROPs to copolymerize vinyl and cyclic ester monomers for rational design and precise synthesis of multiblock copolymers with advanced architectures and functionalities.
研究领域:
高分子化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
Polymers
·
2017
·Vol. 9
·期 12
·681
·
IF 3.364
Jianbo Tan,Xueliang Li,Jun He,Qin Xu,Yuxuan Zhang,Xiaocong Dai,Liangliang Yu,Ruiming Zeng,Li Zhang
Herein, we report a photoinitiated reversible addition-fragmentation chain transfer (RAFT) dispersion copolymerization of methyl methacrylate (MMA) and methyl methacrylic (MAA) for the preparation of highly monodisperse carboxyl-functionalized polymeric microspheres. High rates of polymerization were observed, with more than 90% particle yields being achieved within 3 h of UV irradiation. Effects of reaction parameters (e.g., MAA concentration, RAFT agent concentration, photoinitiator concentration, and solvent composition) were studied in detail, and highly monodisperse polymeric microspheres were obtained in most cases. Finally, silver (Ag) composite microspheres were prepared by in situ reduction of AgNO3using the carboxyl-functionalized polymeric microspheres as the template. The obtained Ag composite microspheres were able to catalyze the reduction of methylene blue (MB) with NaBH4as a reductant.Keywords:carboxyl-functionalized microspheres;RAFT polymerization;photoinitiated dispersion polymerization
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY
·
2016
·Vol. 55
·期 1
·164-174
·
IF 3.114
Yue Lv,Zhifen Liu,Anqi Zhu,Zesheng An
A new methodology based on glucose oxidase (GOx) deoxygenation and hydrogen peroxide/vitamin C (H 2 O 2 /Vc) redox initiation for conducting RAFT polymerization at low temperature in air is reported. GOx catalyzes reduction of oxygen in the presence of glucose to generate hydrogen peroxide, which is directly used to constitute a redox pair with Vc for the efficient generation of hydroxyl radicals to initiate RAFT polymerization in air. Various experimental parameters including temperature, stirring speed, prepolymerization incubation time, and concentrations of Vc, glucose, and GOx were evaluated with respect to monomer conversion, molecular weight, and dispersity. Efficient removal of oxygen is typically realized within 10 min before polymerization is initiated by addition of Vc, and high conversions are achieved within 5 h. Well-defined homopolymers and block copolymers have been efficiently synthesized with high monomer conversions and low dispersities (< 1.2). Using this new methodology, it is possible to conduct controlled RAFT polymerizations in both open and sealed vessels, though lower conversions but less termination by oxygen are typically observed for the sealed systems. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 164–174
研究领域:
高分子化学
·
生物催化
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）