Effect of silica nanoparticle loading and surface modification on the kinetics of RAFT polymerization

Abstract S-(thiobenzoyl)thioglycolic acid was used to synthesize poly(methyl methacrylate) via reversible addition-fragmentation chain transfer (RAFT) polymerization. To study the polymerization kinetics, in situ polymerization reactions were performed with different loading of nanoparticles. To investigate the effect of surface modification on the polymerization kinetics, similar reactions were performed with 3-methacryloxypropyldimethylchlorosilane-modified nanoparticles. Conversion, reaction rate, molecular weight and polydispersity index (PDI) were monitored during polymerization. According to results, pseudo-first order kinetics is achieved, but the rate constant of chain transfer reaction to the RAFT agent (Ctr) has a very small value. Adding nanoparticles causes no considerable change in the kinetic curves, while there is an optimum value for nanoparticles loading in which the polymerization rate reaches its maximum level. A similar trend is observed for molecular weight; however, increasing silica content results in an increase in PDI values. In comparison with pristine silica nanoparticles, the polymerization rate increases slowly in the case of modified particles. Also, molecular weight and PDI for free and graft chains are studied separately. The molecular weight of free chains increases with increasing nanoparticles loading up to 7 wt% and then decreases, while PDI values increase continually by adding nanoparticles. However, for graft chains, molecular weight and PDI values increase with increasing nanoparticle content.

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Synthesis and characterization of triphenylamine and Bbis(indolyl)methane center-functionalized polymer via reversible addition-fragmentation chain transfer polymerization

e-Polymers ◽

10.1515/epoly.2008.8.1.256 ◽

2008 ◽

Vol 8 (1) ◽

Cited By ~ 1

Author(s):

Jie Xu ◽

Wei Shang ◽

Jian Zhu ◽

Zhenping Cheng ◽

Nianchen Zhou ◽

...

Keyword(s):

Molecular Weight ◽

Chain Transfer ◽

Raft Polymerization ◽

Chloroform Solution ◽

Monomer Conversion ◽

Benzyl Ester ◽

Chain Extension ◽

Reversible Addition ◽

Raft Agent ◽

Cyclic Voltammetry Method

AbstractA novel bis-functional reversible addition-fragmentation chain transfer (RAFT) agent bearing triphenylamine (TPA) and bis(indolyl)methane (BIM) groups, {4-[bis(1-carbodithioic acid benzyl ester-indol-3-yl)methyl]phenyl}diphenylamine (BCIMPDPA), was synthesized and successfully used as the RAFT agent to mediate the polymerization of styrene (St). The polymerization results showed that reversible addition-fragmentation chain transfer (RAFT) polymerization of St could be well controlled. The kinetic plot showed it was of first order and the numberaverage molecular weight (Mn(GPC)) of the polymer measured by GPC increased linearly with monomer conversion, simultaneously, the molecular weight distribution of the polymer was also relatively narrow. In addition, the existence of the TPA and BIM groups in the middle of polymer chain was confirmed by chain extension reaction and 1H NMR spectrum. The optical properties of the functionalized polystyrene (PS) in chloroform solution were also investigated. Furthermore, the redox process of the RAFT agent and the functionalized PS were studied by cyclic voltammetry method.

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Living free radical polymerization of styrene with 2-cyanoprop-2-yl dithionaphthalate as RAFT agent

e-Polymers ◽

10.1515/epoly.2003.3.1.576 ◽

2003 ◽

Vol 3 (1) ◽

Author(s):

Zhu Jian ◽

Zhu Xiulin ◽

Zhou Di ◽

Chen Jianying

Keyword(s):

Molecular Weight ◽

Reaction Temperature ◽

Raft Polymerization ◽

Monomer Concentration ◽

Gel Permeation Chromatography ◽

Monomer Conversion ◽

Bulk Polymerization ◽

Polymerization Rate ◽

Chain Extension ◽

Raft Agent

Abstract The reversible addition-fragmentation chain transfer (RAFT) bulk polymerization of styrene was studied using 2-cyanoprop-2-yl dithionaphthalate (CPDN) as RAFT agent in the presence or absence of 2,2’-azoisobutyronitrile (AIBN). The results of both thermally and AIBN-initiated styrene (St) polymerizations show that St can be polymerized in a controlled way using CPDN as RAFT agent; i.e., the polymerization rate is first order with respect to monomer concentration, and molecular weight increases linearly with monomer conversion. The molecular weights obtained from gel permeation chromatography are close to the theoretical values and molecular weight distributions are relatively narrow (Mw/Mn < 1.2). It is confirmed by chain extension reaction that the polymer prepared via RAFT polymerization can be used as a macroRAFT agent. The effects of reaction temperature and mole ratios [St]0/[CPDN]0/[AIBN]0 on the polymerization were investigated. The results indicate that the reaction temperature has a positive effect on the polymerization rate, but little effect on molecular weight and molecular weight distribution, and the optimum mole ratios were found to be [CPDN]0/[AIBN]0 > 4/3 and [St]0/[CPDN]0 < 800.

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Synthesis of azobenzene-centered (co)polymers via reversible addition-fragmentation chain transfer (RAFT) polymerization

e-Polymers ◽

10.1515/epoly.2007.7.1.1059 ◽

2007 ◽

Vol 7 (1) ◽

Author(s):

Yu Liping ◽

Zhu Jian ◽

Cheng Zhenping ◽

Zhang Zhengbiao ◽

Zhang Wei ◽

...

Keyword(s):

Molecular Weight ◽

Chain Transfer ◽

Raft Polymerization ◽

Gel Permeation Chromatography ◽

Polymer Chains ◽

Dimethyl Formamide ◽

Reversible Addition ◽

Raft Agent ◽

Pentablock Copolymers ◽

Ft Ir

Abstract An azobenzene-based dithiocarbamate, 4,4'-bis[2-(carbazole-N-dithio formatyl)-2-methyl-propionatyl]-azobenzene (CDMPA), was synthesized and used as the chain transfer agent (CTA) for reversible addition-fragmentation chain transfer (RAFT) polymerization of styrene in anisole solution. Well-defined azobenzene-centered and carbazole-ended polystyrene (PS) with well-controlled molecular weight (Mn) and narrow molecular weight distributions (Mw/Mn) was obtained. The good agreement between the theoretical molecular weight (Mn,th) and the 1H NMR determined molecular weight (Mn,NMR) indicated that most of the polymer chains contained an azo-functional center-group end-capped with the carbazole moieties, which were derived from the RAFT agent. The obtained polystyrene (PS) showed a strong ultraviolet absorption in tetrahydrofuran (THF) and emitted fluorescence after excited by UV-irradiation in N,N’-dimethyl formamide (DMF) solutions. The PS was used as the macro-RAFT agent to carry out the polymerization of methyl acrylate (MA) and N-isopropylacrylamide (NIPAAM). Triblock copolymers (PMA-b-PS-b-PMA), and pentablock copolymers (PNIPAAM-b-PMA-b-PS-b-PMA-b-PNIPAAM) were obtained, respectively. These copolymers were characterized by gel permeation chromatography (GPC), FT-IR spectroscopy and NMR spectroscopy.

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Nano-Assemblies from Amphiphilic PnBA-b-POEGA Copolymers as Drug Nanocarriers

Polymers ◽

10.3390/polym13071164 ◽

2021 ◽

Vol 13 (7) ◽

pp. 1164

Author(s):

Angeliki Chroni ◽

Thomas Mavromoustakos ◽

Stergios Pispas

Keyword(s):

Molecular Weight ◽

Chain Transfer ◽

Raft Polymerization ◽

Polymeric Nanocarriers ◽

Reversible Addition ◽

2D Noesy ◽

Drug Nanocarriers ◽

Glycol Methyl Ether ◽

Different Molecular Weight

The focus of this study is the development of highly stable losartan potassium (LSR) polymeric nanocarriers. Two novel amphiphilic poly(n-butyl acrylate)-block-poly(oligo(ethylene glycol) methyl ether acrylate) (PnBA-b-POEGA) copolymers with different molecular weight (Mw) of PnBA are synthesized via reversible addition fragmentation chain transfer (RAFT) polymerization, followed by the encapsulation of LSR into both PnBA-b-POEGA micelles. Based on dynamic light scattering (DLS), the PnBA30-b-POEGA70 and PnBA27-b-POEGA73 (where the subscripts denote wt.% composition of the components) copolymers formed micelles of 10 nm and 24 nm in water. The LSR-loaded PnBA-b-POEGA nanocarriers presented increased size and greater mass nanostructures compared to empty micelles, implying the successful loading of LSR into the inner hydrophobic domains. A thorough NMR (nuclear magnetic resonance) characterization of the LSR-loaded PnBA-b-POEGA nanocarriers was conducted. Strong intermolecular interactions between the biphenyl ring and the butyl chain of LSR with the methylene signals of PnBA were evidenced by 2D-NOESY experiments. The highest hydrophobicity of the PnBA27-b-POEGA73 micelles contributed to an efficient encapsulation of LSR into the micelles exhibiting a greater value of %EE compared to PnBA30-b-POEGA70 + 50% LSR nanocarriers. Ultrasound release profiles of LSR signified that a great amount of the encapsulated LSR is strongly attached to both PnBA30-b-POEGA70 and PnBA27-b-POEGA73 micelles.

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Synthesis and characterization of a naphthalimide–dye end-labeled copolymer by reversible addition–fragmentation chain transfer (RAFT) polymerization

Canadian Journal of Chemistry ◽

10.1139/v10-134 ◽

2011 ◽

Vol 89 (3) ◽

pp. 317-325 ◽

Cited By ~ 10

Author(s):

Binxin Li ◽

Daniel Majonis ◽

Peng Liu ◽

Mitchell A. Winnik

Keyword(s):

Chain Transfer ◽

Raft Polymerization ◽

Polymer Composition ◽

Cooh Group ◽

Agent Based ◽

Molecular Weights ◽

Reversible Addition ◽

Raft Agent ◽

End Use ◽

Naphthalimide Dye

We describe the synthesis of an end-functionalized copolymer of N-(2-hydroxypropyl)methacrylamide (HPMA) and N-hydroxysuccinimide methacrylate (NMS) by reversible addition–fragmentation chain transfer (RAFT) polymerization. To control the polymer composition, the faster reacting monomer (NMS) was added slowly to the reaction mixture beginning 30 min after initating the polymerization (ca. 16% HPMA conversion). One RAFT agent, based on azocyanopentanoic acid, introduced a –COOH group to the chain at one end. Use of a different RAFT agent containing a 4-amino-1,8-naphthalimide dye introduced a UV–vis absorbing and fluorescent group at this chain end. The polymers obtained had molecular weights of 30 000 and 20 000, respectively, and contained about 30 mol% NMS active ester groups.

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Effect of stabilizer concentration and controller structure and composition on polymerization rate and molecular weight development in RAFT polymerization of styrene in supercritical carbon dioxide

Polymer ◽

10.1016/j.polymer.2009.08.036 ◽

2009 ◽

Vol 50 (21) ◽

pp. 5024-5030 ◽

Cited By ~ 13

Author(s):

Gabriel Jaramillo-Soto ◽

Pedro R. García-Morán ◽

Francisco J. Enríquez-Medrano ◽

Hortensia Maldonado-Textle ◽

Martha E. Albores-Velasco ◽

...

Keyword(s):

Carbon Dioxide ◽

Molecular Weight ◽

Supercritical Carbon Dioxide ◽

Raft Polymerization ◽

Polymerization Rate ◽

Stabilizer Concentration ◽

Supercritical Carbon

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Study on MMA and BA Emulsion Copolymerization Using 2,4-Diphenyl-4-methyl-1-pentene as the Irreversible Addition–Fragmentation Chain Transfer Agent

Polymers ◽

10.3390/polym12010080 ◽

2020 ◽

Vol 12 (1) ◽

pp. 80

Author(s):

Zuxin Zhang ◽

Daihui Zhang ◽

Gaowei Fu ◽

Chunpeng Wang ◽

Fuxiang Chu ◽

...

Keyword(s):

Molecular Weight ◽

Tensile Properties ◽

Chain Transfer ◽

Monomer Conversion ◽

Degree Of Polymerization ◽

Polymerization Rate ◽

Chain Transfer Agent ◽

Regulation Mechanism ◽

Transfer Coefficients ◽

Emulsion Copolymerization

As a chain transfer agent, 2,4-diphenyl-4-methyl-1-pentene (αMSD) was first introduced in the emulsion binary copolymerization of methyl methacrylate (MMA) and butyl acrylate (BA) based on an irreversible addition–fragmentation chain transfer (AFCT) mechanism. The effects of αMSD on molecular weight and its distribution, the degree of polymerization, polymerization rate, monomer conversion, particle size, and tensile properties of the formed latexes were systematically investigated. Its potential chain transfer mechanism was also explored according to the 1H NMR analysis. The results showed that the increase in the content of αMSD could lead to a decline in molecular weight, its distribution, and the degree of polymerization. The mass percentage of MMA in the synthesized polymers was also improved as the amounts of αMSD increased. The chain transfer coefficients of αMSD for MMA and BA were 0.62 and 0.47, respectively. The regulation mechanism of αMSD in the emulsion polymerization of acrylates was found to be consistent with Yasummasa’s theory. Additionally, monomer conversion decreased greatly to 47.3% when the concentration of αMSD was higher than 1 wt% due to the extremely low polymerization rate. Moreover, the polymerization rate was also decreased probably due to the desorption and lower reactivity of the regenerative radicals from αMSD. Finally, the tensile properties of the resulting polyacrylate films were significantly affected due to the presence of αMSD.

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Facile Access to Chain Length Dependent Termination Rate Coefficients via Reversible Addition−Fragmentation Chain Transfer (RAFT) Polymerization: Influence of the RAFT Agent Structure

Macromolecules ◽

10.1021/ma0358428 ◽

2004 ◽

Vol 37 (7) ◽

pp. 2404-2410 ◽

Cited By ~ 38

Author(s):

Achim Feldermann ◽

Martina H. Stenzel ◽

Thomas P. Davis ◽

Philipp Vana ◽

Christopher Barner-Kowollik

Keyword(s):

Chain Length ◽

Chain Transfer ◽

Raft Polymerization ◽

Rate Coefficients ◽

Termination Rate ◽

Reversible Addition ◽

Raft Agent ◽

Agent Structure

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EFFECT OF REVERSIBLE ADDITION-FRAGMENTATION CHAIN TRANSFER EMULSION STYRENE–BUTADIENE RUBBER ON THE PROPERTIES OF SILICA COMPOUNDS

Rubber Chemistry and Technology ◽

10.5254/rct.20.80432 ◽

2020 ◽

pp. 000-000 ◽

Cited By ~ 1

Author(s):

Hyunsung Mun ◽

Kiwon Hwang ◽

Gwanghoon Kwag ◽

JaeKon Suh ◽

Duseong Ahn ◽

...

Keyword(s):

Molecular Weight ◽

Molecular Weight Distribution ◽

Weight Distribution ◽

Raft Polymerization ◽

Styrene Butadiene Rubber ◽

Butadiene Rubber ◽

Narrow Molecular Weight Distribution ◽

Reversible Addition ◽

Raft Agent ◽

Styrene Butadiene

ABSTRACT In recent years, solution styrene–butadiene rubber (SSBR), which has a narrow molecular weight distribution, controllable microstructure, and chain end functionality, is mainly used as base rubber for passenger car tire tread compounds. However, SSBR has a lower molecular weight than that of emulsion SBR (ESBR) because it is difficult to increase the molecular weight of SSBR. In contrast, ESBR can easily increase the molecular weight; however, it has a broad molecular weight distribution. The reversible addition-fragmentation chain transfer (RAFT) polymerization technique is applicable to the emulsion polymerization. Polymers with narrow molecular weight distributions can be obtained by the RAFT polymerization because the RAFT agent prevents the coupling reaction of the growing chain radicals. In this case, ESBR having a narrow molecular weight distribution, which is an advantage of SSBR, and a high molecular weight, which is an advantage of ESBR, can be synthesized. Therefore, we synthesized RAFT ESBR and fabricated its compounds with silica filler. We confirmed that the physical properties of the RAFT ESBR silica compound are different from those of the ESBR silica compound. In addition to the narrow molecular weight distribution of the RAFT ESBR, the trithiocarbonyl group of the RAFT agent in the RAFT ESBR chain molecules affects the physical properties.

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