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

Polymers ◽  
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.

scholarly journals Influence of structure and solubility of chain transfer agents on the RAFT control of dispersion polymerisation in scCO2

2021 ◽  
Author(s):  
Ana A. C. Pacheco ◽  
Arnaldo F. da Silva Filho ◽  
Kristoffer Kortsen ◽  
Magnus W. D. Hanson-Heine ◽  
Vincenzo Taresco ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Methyl Methacrylate ◽  
Chain Transfer ◽  
Good Control ◽  
Chain Transfer Agent ◽  
Methylpropionic Acid ◽  
Transfer Agents

RAFT dispersion polymerisation of methyl methacrylate is performed in scCO2 with 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid (DDMAT) present as chain transfer agent (CTA) and surprisingly shows good control over PMMA molecular weight.

RAFT Graft Polymerization of 2-(Dimethylaminoethyl) Methacrylate onto Cellulose Fibre

2006 ◽  
Vol 59 (10) ◽  
pp. 737 ◽  
Author(s):  
Debashish Roy ◽  
James T. Guthrie ◽  
Sébastien Perrier
Keyword(s):  
Graft Polymerization ◽  
Chain Transfer ◽  
Raft Polymerization ◽  
Cellulose Fibre ◽  
Monomer Conversion ◽  
Living System ◽  
Degree Of Polymerization ◽  
Polymerization Time ◽  
Grafted Polymer ◽  
Reversible Addition

Poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) was grafted from cellulose by reversible addition–fragmentation chain transfer (RAFT) polymerization. The use of a free chain transfer agent in solution allowed for a better control over graft ratio, chain length of grafted polymer, monomer conversion, and homopolymer formation in solution. An increase in polymerization time or degree of polymerization led to an increase in graft ratio, as expected from a living system.

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

2012 ◽  
Vol 32 (1) ◽  
Author(s):  
Mehdi Salami-Kalajahi ◽  
Vahid Haddadi-Asl ◽  
Farid Behboodi-Sadabad ◽  
Saeid Rahimi-Razin ◽  
Hossein Roghani-Mamaqani
Keyword(s):  
Molecular Weight ◽  
Surface Modification ◽  
Chain Transfer ◽  
Raft Polymerization ◽  
Silica Nanoparticle ◽  
Maximum Level ◽  
Silica Content ◽  
Considerable Change ◽  
Polymerization Rate ◽  
Raft Agent

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.

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

e-Polymers ◽  
2008 ◽  
Vol 8 (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.

Synthesis and Evalution of Enteric Aqueous Polymethacrylate Coating Material

2013 ◽  
Vol 483 ◽  
pp. 56-60 ◽  
Author(s):  
Xiao Qi Chen ◽  
Chao Liu ◽  
Hai Jun Zhou ◽  
Xiao Lei Zhang ◽  
Fei Wang ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Dissolution Rate ◽  
Methacrylic Acid ◽  
Chain Transfer ◽  
Raw Materials ◽  
Ethyl Acrylate ◽  
Coating Material ◽  
Chain Transfer Agent ◽  
Continuous Polymerization ◽  
Enteric Coated

A kind of enteric-coated pharmaceutical coating material, which can be dissolved in pH>5.5 medium, was successfully prepared by pre-emulsionsemi-continuous polymerization methods with equal molecular mass of methacrylic acid and ethyl acrylate as main raw materials. The effects of the initiator and chain transfer agent on the molecular weight and the performance of the emulsion were discussed. The obtained compound was used as the coating material of Lansoprazole capsule, and the dissolution rate was measured. The results show that polymethacrylat emulsion with 1.83×105 of molecular weight was obtained when the dosage of the initiator and the chain transfer agent is 0.43% and 0.79% of the total monomer mass, respectively. The dissolution rate of Lansoprazole capsule coated polymethacrylat emulsion in the pH 6.8 medium was greater than 75%.

Controlled/‘living’ polymerization methods

2004 ◽  
Author(s):  
Wayne Hayes ◽  
Steve Rannard
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Chain Transfer ◽  
Living Polymerization ◽  
Degree Of Polymerization ◽  
Polymer Chains ◽  
Chain Growth ◽  
Living Polymerizations ◽  
Living Nature

Chain-growth polymerizations such as free-radical polymerizations are characterized by four key processes:(i) initiation, (ii) propagation, (iii) chain transfer, and (iv) termination. If it is possible to minimize the contribution of chain transfer and termination during the polymerization, it is possible to achieve a level of control over the resulting polymer and achieve a predetermined number average molecular weight and a narrow molecular weight distribution (polydispersity). If such an ideal scenario can be created, the number of polymer chains that are produced is equal to the number of initiator groups; the polymerization will proceed until all of the monomer has been consumed and the polymer chain ends will remain active so that further addition of monomer will lead to continued polymerization. This type of polymerization was termed a ‘living’ polymerization by Szwarc in 1956 and represents one of the ultimate goals of synthetic polymer chemists. Flory determined that in the absence of termination, the number of propagating polymer chains must remain constant and that the rate of polymerization for each growing chain must be equal. In this situation, the number average degree of polymerization (DPn) and hence the molecular weight of the polymer can be predicted by simple consideration of the monomer to initiator ratio (see eqns (1) and (2), respectively). Several key criteria are used to elucidate the ‘living’ nature of a polymerization. For a polymerization to be considered ‘living’, the rate of initiation must exceed the rate of propagation. Therefore, all the propagating polymer chains are formed simultaneously and grow at the same rate. If this situation did not occur, the first chains formed would be longer than those initiated later and the molecular weight distribution of the propagating chains would broaden. In addition, an ideal ‘living’ or ‘immortal’ polymerization must not exhibit any termination of the propagating polymer chains over the lifetime of the reaction. Consequently, ‘living’ polymerizations are characterized by very narrow molecular weight distributions (Mw/Mn < 1.2).

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

e-Polymers ◽  
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.

scholarly journals Correction: Tacticity, molecular weight, and temporal control by lanthanide triflate-catalyzed stereoselective radical polymerization of acrylamides with an organotellurium chain transfer agent

2020 ◽  
Vol 11 (46) ◽  
pp. 7439-7441
Author(s):  
Yuji Imamura ◽  
Takehiro Fujita ◽  
Yu Kobayashi ◽  
Shigeru Yamago
Keyword(s):  
Molecular Weight ◽  
Radical Polymerization ◽  
Chain Transfer ◽  
Chain Transfer Agent ◽  
Temporal Control

Correction for ‘Tacticity, molecular weight, and temporal control by lanthanide triflate-catalyzed stereoselective radical polymerization of acrylamides with an organotellurium chain transfer agent’ by Yuji Imamura et al., Polym. Chem., 2020, DOI: 10.1039/d0py01280g.

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