POLYMER
·
2024
·
IF 4.1
Jincheng Sui,Xiaoyu Miao,Xin Cao,Qiuyu Ding,Longqiang Xiao,Linxi Hou
The polymer dispersity index (PDI) is a vital metric for characterizing molecular weight distribution, significantly influencing polymer material performance. However, achieving precise control over PDI in polymer synthesis remains a substantial challenge. In this study, we introduce an approach for modifying the PDI of poly(methyl acrylate) (PMA) in switchable reversible addition-fragmentation chain transfer radical polymerizations (RAFT). The devised strategy involves the utilization of photoresponsive hexaarylbiimidazole (HABI) as a mediator, coupled with temporal programming, to cyclically deactivate and reactivate propagating radicals at distinct stages throughout the polymerization process. The precise timing of the light stimulus is facilitated through computer-controlled single-chip microcomputer technology, ensuring automatic modulation of the optical state and mitigating operational inaccuracies. By manipulating external light conditions, the PDI of PMAs can be systematically adjusted within the range of 1.80–2.59. Validation through successful chain-extension experiments and analysis via MALDI-TOF MS confirm the preservation of good chain-end fidelity across PMAs with varying PDIs fabricated through this methodology.
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
CELLULOSE
·
2018
·Vol. 25
·期 3
·1705-1714
·
IF 3.809
Liu Ting,Ding Enyong,Xue Feng
Polymer grafting is an efficient way to obtain functional cellulose nanocrystals. In this work, we used a “macro-RAFT (macromolecular reversible addition–fragmentation chain transfer) agent-assisted” strategy, which adds extra amount of amphiphilic macro-RAFT agent with low molecular weight to graft poly(N,N-dimethylacrylamide) (PDMA) from cellulose nanocrystals. Successful grafting was evidenced by different characterization methods, and a high weight ratio of grafted PDMA was obtained (77.6%). The grafting process was studied through the weight ratio of grafted PDMA, monomer conversion, and the molecular weight of free and grafted PDMA at different reaction time. As a result, we have suggested that there were three types of grafted polymer chains on cellulose nanocrystals in this reaction system and discussed their evolution during the grafting reaction. Finally, we summarized several key factors for successful grafting in this macro-RAFT agent-assisted strategy.
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
JOURNAL OF POLYMER SCIENCE
·
2024
·
IF 3.9
Weijie Zhang,Yuxiang Zhang,Jingjing Xiao,Xiaowei Wang,Lei Liu,Jibin Han,Hui Wang,Anchao Feng
Lead halide perovskite has currently emerged as a research hotspot in the field of photocatalysis due to its exceptional photovoltaic characteristics. Despite its potential, the susceptibility to degradation under harsh conditions such as light, humidity, and polar solvents poses a significant challenge. To counteract this, a strategy employing silica to shield the perovskite surface is conducted, thereby enhancing its stability. The resulting composite MAPbBr 3 @SiO 2 is then deployed as a photocatalyst in the photoinduced electron/energy transfer reversible addition fragmentation chain transfer (PET-RAFT) polymerization of butyl acrylate within polar solvents. The catalytic performance across different RAFT polymerization systems including varying the RAFT reagents, catalyst concentrations, and solvent types is meticulously examined. Remarkably, with a photocatalyst loading of merely 0.004 wt% and under a blue light intensity of 6 mW/cm 2 , over 80% monomer conversion can be achieved in 4 h. Moreover, the molecular weight distribution ( Đ ) consistently remains within the narrow range of 1.0–1.2 across all experimental setups, which proves the controllable nature of the PET-RAFT process. Owning the advantages of low photocatalyst requirement, compatibility with polar solvents, and narrow molecular weight distribution, PET-RAFT polymerization mediated by MAPbBr 3 @SiO 2 holds promise for scalable manufacturing and industrial-scale applications. Graphical Silica-coated hybrid lead halide perovskite nanocrystals are prepared and applied as photocatalysts in a PET-RAFT polymerization within polar solvents. High monomer conversion rates and polymers with narrow molecular weight distribution can be achieved. The polymerization process is notably efficient and can be conducted with minimal photocatalyst amounts, underscoring the superior efficiency and broad applicability of our novel photocatalyst system.
研究领域:
材料科学
·
高分子化学
·
光催化领域
✓ 已验证
产品关联
DOI
高影响因子
Polymers
·
2019
·Vol. 11
·期 5
·892
·
IF 3.164
Huazhen Tao,Lei Xia,Guang Chen,Tianyou Zeng,Xuan Nie,Ze Zhang,Yezi You
Photocatalyzed polymerization using organic molecules as catalysts has attracted broad interest because of its easy operation in ambient environments and low toxicity compared with metallic catalysts. In this work, we reported that 4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole (DTBT) can act as an efficient photoredox catalyst for photoinduced electron transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization under green light irradiation. Well-defined (co)polymers can be obtained using this technique without any additional additives like noble metals and electron donors or acceptors. The living characteristics of polymerization were verified by kinetic study and the narrow dispersity (Đ) of the produced polymer. Excellent chain-end fidelity was demonstrated through chain extension as well. In addition, this technique showed great potential for various RAFT agents and monomers including acrylates and acrylamides.Keywords:organic photoredox catalyst;green light;PET-RAFT polymerization
研究领域:
高分子化学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
POLYMER
·
2014
·Vol. 55
·期 10
·2380-2388
·
IF 3.766
Jianbo Tan,Xin Rao,Dan Jiang,Jianwen Yang,Zhaohua Zeng
One-stage photoinitiated RAFT dispersion polymerization (PRDP) has been studied. It was found that the structure of the RAFT agent has a strong influence on the particle morphology . Carboxyl-functionalized trithiocarbonates, including S,S′-bis(α,α′-dimethyl-α″-acetic acid) trithiocarbonate (BDMAT), S-1-dodecyl-S′-(α,α′-dimethyl-α″-acetic acid) trithiocarbonate (DDMAT), S-1-ethyl-S′-(α,α′-dimethyl-α″-acetic acid) trithiocarbonate (EDMAT), were found to be suitable RAFT agents for preparing highly monodisperse microspheres . GPC traces suggested that the polymerization does not follow the typical controlled/living process due to the low RAFT agent concentration in comparison with photoinitiator concentration. Particle size and uniformity changed very little with a wide range of concentrations of the stabilizer and photoinitiator. Highly monodisperse microspheres were obtained even at low stabilizer concentration (5 wt% PVP). Increasing the monomer concentration led to an increase in particle diameter with an exponent of 0.63, which is similar in scale to conventional dispersion polymerization . The microspheres were monodisperse at monomer concentrations ranging from 5 to 15 wt%.
研究领域:
高分子化学
·
材料科学
·
大分子化学
·
纳米材料
✓ 已验证
产品关联
DOI
高影响因子
MACROMOLECULES
·
2024
·
IF 5.1
Priyanka Chohan,Csilla György,Oleksandr O. Mykhaylyk,Giles M. Prentice,Sorin V. Filip,Marc J. Payne,Gouranga Manna,Steven P. Armes
We report the reversible addition–fragmentation chain transfer (RAFT) dispersion polymerization of 2-hydroxyethyl methacrylate (HEMA) in n-dodecane using a poly(lauryl methacrylate) (PLMA) precursor at 90 °C. This formulation is an example of polymerization-induced self-assembly (PISA), which leads to the formation of a colloidal dispersion of spherical PLMA–PHEMA nanoparticles at 10–20% w/w solids. PISA syntheses involving polar monomers in non-polar media have been previously reported but this particular system offers some unexpected and interesting challenges in terms of both synthesis and characterization. First, GPC analysis requires chemical derivatization of the pendent hydroxyl groups in the PHEMA block using excess acetyl chloride to ensure that both blocks are fully soluble in chloroform. Second, DLS, TEM and 1H NMR spectroscopy studies of the periodically sampled polymerizing mixture indicate the transient formation of anomalously large, colloidally unstable aggregates at around 50% conversion, which approximately corresponds to the maximum rate of polymerization. Remarkably, such aggregates immediately break up to form well-defined nanoparticles, which remain colloidally stable at the end of the HEMA polymerization. Moreover, depending on the target degree of polymerization (DP) for the PHEMA block, TEM studies typically indicate bimodal particle size distributions for PLMA–PHEMA nanoparticles prepared using a one-shot batch protocol. This is attributed to a side-reaction between HEMA monomer and the dithiobenzoate-based RAFT agent. Fortunately, this problem can be prevented by conducting such PISA syntheses under monomer-starved conditions by continuous addition of the HEMA monomer using a syringe pump. Alternatively, unimodal spheres can also be produced via adding HEMA in multiple batches. This PISA formulation has been optimized to produce monomodal particle size distributions while targeting a PHEMA DP of up to 1000 at the maximum possible copolymer concentration. Finally, time-resolved small-angle X-ray scattering (SAXS) studies indicate the rapid formation of well-defined near-monodisperse spheres when targeting PLMA14–PHEMA50 nanoparticles.
研究领域:
材料科学
·
高分子化学
✓ 已验证
DOI
PubMed
高影响因子
MACROMOLECULAR CHEMISTRY AND PHYSICS
·
2013
·Vol. 214
·期 20
·2266-2275
·
IF 2.386
Jixian Liu,Zhen Liu,Xiong Luo,Xidan Zong,Jingquan Liu
The preparation of biodegradable and positively charged graphene–polymer nanocomposite for DNA uptake and release is presented. A pyrene-terminated poly(2-(dimethylamino) ethyl acrylate) is firstly synthesized via reversible addition–fragmentation chain transfer (RAFT) polymerization, followed by the attachment onto the graphene surface via the π–π stacking interaction. The positively charged polymer brushes benefit the uptake of the negatively charged DNA fragment via static interaction and the built-in disulfide linkage between the polymer chain and graphene surface allows the biodegradable release of DNA in the presence of reducing agents. X-ray photoelectron spectroscopy manifests the binding of DNA molecules to the polymer chains and agarose gel electrophoresis confirms the release of DNA.
研究领域:
材料科学
·
生物医学工程
✓ 已验证
产品关联
DOI
高影响因子
MACROMOLECULES
·
2016
·
IF 5.554
Shaoning Liang,Xiaohui Li,Wen-Jun Wang,Bo-Geng Li,Shiping Zhu
We report the reversible addition–fragmentation chain transfer (RAFT) solution copolymerization of methyl methacrylate (MMA) with a cleavable divinyl comonomer, bis(2-methacryloyl)oxyethyl disulfide (BMAODS). 2-Cyano-2-propyldodecyl trithiocarbonate was used as a RAFT chain transfer agent and 2,2′-azobis(2-methylpropionitrile) as an initiator. The selective cleavage of BMAODS disulfide bonds was used to collect primary chains for the determination of the branching density (BD). The effects of initial monomer concentration, vinyl/divinyl ratio, and primary chain length on the branching and cyclization reactions were thoroughly investigated. It was found that more than 50% pendent double bonds from BMAODS were consumed in cyclization rather than in branching. The BD increased linearly with the conversion up to approximately 60% conversion. The monomer concentration was found to be the most efficient parameter in promoting branching. Increasing divinyl monomer ratio and primary chain length favored cyclization over branching. The work provides experimental evidence to support the random branching mechanism in RAFT copolymerization of vinyl and divinyl monomers.
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
CHINESE CHEMICAL LETTERS
·
2010
·
IF 0.643
Li Ping Wang,Li Min Zhao,Wen Zhi Li,Rui Qing Chu,Long Tan,Xiu Xiu Zhao,Gang Wang
The triple-shelled hollow spheres with optical properties were prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization. After removal the core templates of the poly (styrene), the hollow silica spheres were obtained. The coating process of poly (methyl methacrylate) (PMMA) on the hollow silica spheres surface via surface RAFT polymerization was performed subsequently. The polymers coated on the hollow spheres surfaces were end-functionalized by trithiocarbonate , and they were used as RAFT agent to proceed the chain extension polymerization using Tb complex as monomer . The samples were characterized by FT-IR, SEM and luminescence spectroscopy respectively. The results indicated that the triple-shelled hollow spheres had been prepared successfully and the average diameter of the hollow core was about 1 μm.
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
BIOMACROMOLECULES
·
2014
·
IF 5.788
Yuanyuan Zhuang,Yue Su,Yu Peng,Dali Wang,Hongping Deng,Xiaodong Xi,Xinyuan Zhu,Yunfeng Lu
A novel kind of redox-responsive polymeric drug delivery system has been designed and prepared successfully through the coupling of the multithiol branched polymers and thiol-containing drugs. The branched poly((S-(4-vinyl) benzyl S′-propyltrithiocarbonate)-co-(poly(ethylene glycol) methacrylate)) (poly(VBPT-co-PEGMA)) was synthesized by one-pot reaction via reversible addition–fragmentation chain transfer (RAFT) copolymerization. Subsequently, the hydrophobic thiol-containing anticancer drug 6-mercaptopurine (MP) was conjugated to poly(VBPT-co-PEGMA) by thiol–disulfide exchange reaction, resulting in the formation of poly(VBPT-co-PEGMA)-S-S-MP conjugate. Due to its amphiphilicity, poly(VBPT-co-PEGMA)-S-S-MP conjugate self-assembled into amphiphilic micelles in aqueous solution. Under a reductive environment, the disassembly of polymeric micelles resulted in the MP release. Flow cytometry and confocal laser scanning microscopy (CLSM) measurements demonstrated that the poly(VBPT-co-PEGMA)-S-S-MP micelles could be taken up by Raji cells (a Burkitt lymphoma cell line). The viability of the Raji cells incubated with the glutathione (GSH) mediated poly(VBPT-co-PEGMA)-S-S-MP micelles was investigated by Cell Counting Kit-8 (CCK-8) assay. The experimental results showed that the viability of the glutathione monoester (GSH-OEt) pretreated cells was lower than that without pretreatment, while the viability of the buthionine sulfoximine (BSO) pretreated cells was higher than that without pretreatment. The poly(VBPT-co-PEGMA)-S-S-MP micelles could induce the apoptosis of Raji cells, and the apoptosis behavior was dose-dependent. This redox-responsive polymer–drug conjugate provides a promising platform for the delivery of thiol-containing biological molecules.
研究领域:
生物材料学
·
药剂学
·
肿瘤学
✓ 已验证
DOI
PubMed
高影响因子
Polymer Chemistry
·
2013
·Vol. 5
·期 7
·2326-2332
·
IF 5.231
Jiawei Lu,Weidong Zhang,Sarah-Jane Richards,Matthew I. Gibson,Gaojian Chen
Side-chain functionalized glycopolymers have been successfully prepared in a well-controlled manner via a copper(0)-catalyzed one-pot reaction combining living radical polymerisation and ‘click chemistry’. The polymerisation was confirmed by the first-order kinetic plots, the linear relationships between molecular weights and the monomer conversions while keeping relatively narrow polydispersity (<1.33). The click conversion and polymerisation conversion versus reaction time plots for a Cu(0)-catalyzed one-pot reaction elucidate that the rates of click reaction are significantly faster than the polymerisation rates. Modified gold nanorods (GNRs) with glycopolymeric coatings were prepared through the interaction of Au–S bonds and the glycopolymer substituted GNRs showed strong, specific molecular recognition abilities with lectin (PNA).
研究领域:
材料科学
·
生物医学工程
·
化学
✓ 已验证
DOI
高影响因子
Polymer Chemistry
·
2017
·Vol. 8
·期 41
·6407-6415
·
IF 5.375
Ke Wang,Yixin Wang,Wangqing Zhang
Diblock copolymer nano-assemblies of poly(2-hydroxypropyl methacrylate-b-benzyl methacrylate) (PHPMA-b-PBzMA) were synthesized by initiators for continuous activator regeneration atom transfer radical polymerization (ICAR ATRP) using the CuIIBr2/tris(pyridin-2-ylmethyl)-amine (TPMA) complex as a catalyst under dispersion conditions and were compared with those obtained by RAFT dispersion polymerization. It is found that these two kinds of polymerizations afford good control, as indicated by the linearly increasing molecular weight with monomer conversion and the narrow molecular weight distribution, whereas the ICAR ATRP runs a little faster than RAFT. In the two cases of dispersion polymerization, the morphologies of the PHPMA-b-PBzMA nano-assemblies are similar to each other and change from spheres to wormlike aggregates with block extension, whereas the size of the nano-assemblies by ICAR ATRP is usually larger than those obtained by RAFT. The degree of polymerization (DP) of the poly(2-hydroxypropyl methacrylate) and poly(benzyl methacrylate) blocks affecting the size and/or morphology of the PHPMA-b-PBzMA nano-assemblies is investigated, and the reason for the larger size of the PHPMA-b-PBzMA nano-assemblies by ICAR ATRP is discussed.
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
危险品化学品经营许可证（带存储）