Controlled Synthesis of Branched Polystyrene via RAFT Technique in the Presence of Chain Transfer Monomer p-Vinyl Benzene Sulfonyl Chloride

Cui-Ping Li,Jia-Qiang Wang,Yan Shi,Zan Liu,Jun Lin,Zhi-Feng Fu 한국고분자학회 2012 Macromolecular Research Vol.20 No.8

Branched polystyrene was first obtained via a reversible addition-fragmentation chain transfer (RAFT)process in the presence of chain transfer monomer p-vinyl benzene sulfonyl chloride (VBSC) in benzene at 60 oC with 2-(ethoxycarbonyl)prop-2-yl dithiobenzoate as the RAFT agent and 2,2-azobisisobutyronitrile as an initiator. During the RAFT polymerization, VBSC played the role of branching agent. It could not only copolymerized but also acted as a chain transfer agent due to the polymerizable vinyl group and sulfonyl chloride chain transfer group in the VBSC. Gel permeation chromatography (GPC) traces demonstrated that the number-average molecular weights and molecular weight distributions increased along with monomer conversion. Compared with the RAFT process without VBSC, the resulting polymers had broad molecular weight distributions and the sulfonyl functionality of the resultant polymer at the branching point, indicating the formation of branched polystyrene. The structure of the obtained polystyrene was further analyzed by proton nuclear magnetic resonance (1H NMR) spectroscopy. The findings indicated that the branched polystyrene was mainly formed via the RAFT copolymerization of VBSC and styrene firstly to form polystyrene bearing pendant sulfonyl chloride group, and then the pendant sulfonyl chloride group acted as the chain transfer agent to generate the branched structure. In addition, the degree of branching and VBSC unit in copolymer increased along with the VBSC in the feed, implying that composition and structure of the branched polystyrenes could be tuned by the amount of VBSC in the feed.

Influence of a reversible addition–fragmentation chain transfer agent in the dispersion polymerization of styrene

Saikia, Prakash J.,Lee, Jung Min,Lee, Byung H.,Choe, Soonja Wiley Subscription Services, Inc., A Wiley Company 2007 Journal of polymer science Part A, Polymer chemist Vol.45 No.3

<P>Dispersion polymerization was applied to the controlled/living free-radical polymerization of styrene with a reversible addition–fragmentation chain transfer (RAFT) polymerization agent in the presence of poly(N-vinylpyrrolidone) and 2,2′-azobisisobutyronitrile in an ethanol medium. The effects of the polymerization temperature and the postaddition of RAFT on the polymerization kinetics, molecular weight, polydispersity index (PDI), particle size, and particle size distribution were investigated. The polymerization was strongly dependent on both the temperature and postaddition of RAFT, and typical living behavior was observed when a low PDI was obtained with a linearly increased molecular weight. The rate of polymerization, molecular weight, and PDI, as well as the final particle size, decreased with an increased amount of the RAFT agent in comparison with those of traditional dispersion polymerization. Thus, the results suggest that the RAFT agent plays an important role in the dispersion polymerization of styrene, not only reducing the PDI from 3.34 to 1.28 but also producing monodisperse polystyrene microspheres. This appears to be the first instance in which a living character has been demonstrated in a RAFT-mediated dispersion polymerization of styrene while the colloidal stability is maintained in comparison with conventional dispersion polymerization. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 348–360, 2007</P> <B>Graphic Abstract</B> <P>Dispersion polymerization was applied to the controlled/living free-radical polymerization of styrene with a reversible addition–fragmentation chain transfer polymerization (RAFT) agent in the presence of poly(N-vinylpyrrolidone) and 2,2′-azobisisobutyronitrile in an ethanol medium. The effects of the polymerization temperature and the postaddition of RAFT on the polymerization kinetics, molecular weight, polydispersity index, particle size, and particle size distribution were investigated and found to be strongly dependent on both the temperature and postaddition of RAFT. <img src='wiley_img/0887624X-2007-45-3-POLA21834-gra001.gif' alt='wiley_img/0887624X-2007-45-3-POLA21834-gra001'> </P>

Dependence of Cross-Termination Rate on RAFT Agent Concentration in RAFT Polymerization

Yanggang Gao,Ling Lv,Gang Zou,Qijin Zhang 한국고분자학회 2017 Macromolecular Research Vol.25 No.9

Rate retardation is an intrinsic property of reversible addition-fragmentation chain transfer (RAFT) radical polymerization. One of reasons for this phenomenon is cross-termination reaction between intermediate radicals and other active radicals. With the help of Stationary State Model and experimentally controlling on kt,cross, the kinetics of styrene RAFT polymerization were performed at different concentrations of RAFT agent. Results show that there is a difference in two effects of cross-termination rate coefficient and concentration of intermediate radicals on cross-termination at different RAFT agent concentrations: at the low concentration range, the cross-termination reaction is mainly affected by its rate coefficient, and at the high concentration range, the cross-termination reaction is mainly affected by the concentration of the intermediate radicals. It shows that there is an optimal concentrations of RAFT agent for a RAFT polymerization with the least rate retardation by considering the balance between these two effects.

Polydiacetone Acrylamide as Precursors to Polymer Side-Chain Conjugates

Hongzhen Tan,Zhipeng Yu,Junjie Xiao,Xi Wang,Chunwang Yi,Shengpei Su 한국고분자학회 2018 폴리머 Vol.42 No.4

Polydiacetone acrylamide (PDAAM), a reactive polymer containing pendant ketone groups was synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. Kinetic studies indicated a well-controlled behavior of this RAFT polymerization. The characteristics of this RAFT polymerization was also confirmed by a wellcontrolled chain-extending RAFT polymerization using the above-synthesized PDAAM as a macromolecular chain transfer agent. Acid-catalyzed ketalization of PDAAM with trimethylol propane (TMP) was carried out to obtain the polymer containing pendant cyclic ketal groups and hydroxyl groups, PDAAM-TMP. PCL was grafted from PDAAM-TMP by ring-opening polymerization (ROP) in the presence of tin 2-ethylhexanoate as a catalyst to obtain graft copolymer. Basecatalyzed aldol condensation of PDAAM with benzaldehyde was also used to obtain poly[N-(1,1-dimethyl-3-oxo-5-phenyl-pent-4-enyl)-acrylamide] (PDMOPPEAM) having cinnamoyl groups, and the photoreactivity of polymer with cinnamoyl group was studied by UV-visible and IR absorption spectroscopy. Both of these two polymers prepared from PDAAM were characterized by FTIR and 1H NMR spectroscopy. PDAAM can be a multifunctional platform that can undergo further polymerization by ketalization and aldol condensation.

Synthesis of 9H-fluoren-9-yl benzodithioates and their application as reversible addition–fragmentation chain transfer agents in living radical polymerization of styrene

Yong Liu,Yu-Zi Jin,Chun-He Lee,Jian Huo,이연식 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.2

The reversible addition–fragmentation chain transfer (RAFT) polymerization is one of living radical polymerizations. In this study, four different 9H-fluoren-9-yl benzodithiolates (FBDTs) were synthesized,and used along with azobis(isobutyronitrile) (AIBN), a radical initiator, in polymerization of styrene (ST)at the molar ratio of 3:1. This new transfer agent exhibited the typical characteristic living free radical polymerization behaviors such as good control of molecule weight and narrow molecule weight distribution. It was concluded that the FBDTs can be used as the RAFT agents in free radical polymerization of vinyl monomers.

Ultrasound-promoted direct functionalization of multi-walled carbon nanotubes in water via Diels-Alder “click chemistry”

Le, Cuong M.Q.,Cao, Xuan Thang,Lim, Kwon Taek Elsevier 2017 Ultrasonics sonochemistry Vol.39 No.-

<P><B>Abstract</B></P> <P>A facile and environmentally friendly strategy for grafting polymers onto the surface of multi-walled carbon nanotubes (CNTs) was demonstrated by Diels-Alder “click chemistry”. Firstly, the copolymers of poly(styrene-<I>alt</I>-maleic anhydride) (PSM) were prepared by the reversible addition-fragmentation chain transfer (RAFT) polymerization and subsequently functionalized with furfuryl amine to introduce anchoring groups. The copolymers were then grafted on CNTs via the Diels-Alder reaction in water through a conventional heating-stirring route and ultrasound-assisted method. The obtained nanocomposite materials were characterized by thermogravimetric analysis, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy and transmission electron microscopy. The results indicated that the reaction rate under ultrasound irradiation was accelerated about 12 times than the one under the conventional heating-stirring condition without losing the grafting efficiency. The direct functionalization of CNTs formed a stably dispersed solution in water, promising a green and effective method for industrial process.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The reaction rate was significantly accelerated by ultrasound irradiation. </LI> <LI> Direct functionalization of carbon nanotubes in water without catalyst. </LI> <LI> The process is simple and is not involving any hazardous chemicals. </LI> </UL> </P>

Kinetic Investigations of RAFT Polymerization: Difunctional RAFT Agent Mediated Polymerization of Methyl Methacrylate and Styrene

Jianying Ma,Hui Xuan Zhang 한국고분자학회 2015 Macromolecular Research Vol.23 No.1

A difunctional reversible addition-fragmentation transfer (RAFT) agent, S,S′-bis (α,α′-dimethylacetic acid)trithiocarbonate (BDAT) is synthesized and used as chain transfer agent (CTA) to mediate homopolymerization ofmethyl methacrylate (MMA) and random copolymerization of methyl methacrylate-styrene (St) system, respectively. Kinetic factors of these two polymerizations, which influence polymerization process and characteristics ofpolymers, are investigated. Experimental results show that molecular weights of polymers increase linearly withmonomer conversions and these two polymerization kinetics behaviors exhibit “controlled/living” characteristics. Forthe homopolymerization of MMA, molecular weights increase gradually and are close to their theoretical values. Wherever, for the random copolymerization of MMA-St system, the presence of St has important influence on thekinetics of copolymerization. Addition of St to this system induces an induction period and this period increase withincreasing content of St in monomer composition.

A Novel Hybrid Random Copolymer Poly(MAPOSS-co-NIPAM-co-OEGMA-co-2VP): Synthesis, Characterization, Self-Assembly Behaviors and Multiple Responsive Properties

Yiting Xu,Jianjie Xie,Lingnan Chen,Conghui Yuan,Yinyin Pan,Ling Cheng,Weiang Luo,Birong Zeng,Lizong Dai 한국고분자학회 2013 Macromolecular Research Vol.21 No.12

A novel organic/inorganic hybrid amphiphilic random copolymer poly(methacrylate isobutyl POSS-co-N-isopropylacrylamide-co-oligo(ethylene glycol) methyl ether methacrylate-co-2-vinylpyridine), poly(MAPOSS-co-NIPAM-co-OEGMA-co-2VP), was synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. The self-assembly behavior of random copolymers in aqueous solution was investigated by dynamic light scattering (DLS) as well as transmission electron microscopy (TEM). The results indicate the novel random copolymer in water could self-assemble into spherical aggregates and the self-aggregate size displays a remarkable dependence on pH. The stimuli-responsive characteristics of these assembles were tested by means of UV-vis spectra,DLS and TEM. There is a critic Zn2+ concentration over which the aggregates can be coordinated into well-define spherical aggregate clusters. The critic Zn2+ concentration can be tuned finely through adjusting solution concentration or 2VP amount. Results from UV-vis and DLS reveal that the copolymer solutions exhibit a sharp and intensive lower critical solution temperature (LCST). Some factors such as the solution concentration, molecular weight, pH and copolymer generation, which could affect the cloud point, were studied systematically. The essentially predetermined LCST can be achieved by altering the content of 2VP or pH. In addition, these novel hybrid aggregates can undergo an association/disassociation cycle with the heating and cooling of solution and the degree of reversibility shows a strong concentration dependence. As a novel organic-inorganic hybrid material which can respond to multiple external stimuli including temperature, pH, metal ions with sharp stimuli-responsive behaviors, it is potentially used for biomedicine, catalysis, diagnostics, bioseparations, biosensors and for fundamental investigation.

2-(2-Cyanopropyl) Dithiobenzoate-mediated Grafting Polymerization of Methyl Methacrylate from Vinyl Modified Silica

Deling Li,Guanghui Li,Qing Zhang,Guixian Su,Hongxia Zhang 한국고분자학회 2016 폴리머 Vol.40 No.4

Grafting polymerization of methyl methacrylate (MMA) from vinyl modified silica mediated by 2-(2-cyanopropyl) dithiobenzoate was first conducted. Surface radicals generated by the addition reaction of “free” polymeric radicals with surface vinyl could initiate reversible addition-fragmentation chain transfer (RAFT) grafting polymerization of MMA from silica. The RAFT grafting polymerization of MMA from silica exhibited a living character, evident from the linear relationship of grafting ratio with monomer conversion. Grafting polymerization rate appeared dependent on target molecular weight and initiator concentration because of diffusion-controlled RAFT process on silica. The PMMA-grafted silica allowed for a second-step grafting polymerization due to the existence of dithioester group on the chain ends of grafted PMMA. In this case, surface radicals were generated by the reaction of “free” polymeric radicals with the surface RAFT agents, which differed from the RAFT process of grafting polymerization from vinyl modified silica. This method could be extended to prepare a variety of block copolymers from silica.

Synthesis of ArF Photoresist Polymer Composed of Three Methacrylate Monomers via Reversible Addition-Fragmentation Chain Transfer (RAFT) Polymerization

손해성,차상호,이원기,김동균,윤효진,김명선,김부득,김영호,이재우,김정식,김덕배,김재현,이종찬 한국고분자학회 2011 Macromolecular Research Vol.19 No.7

ArF photoresist polymers were prepared via reversible addition-fragmentation chain transfer (RAFT)polymerization and free radical polymerization (FRP). Three methacrylates with lithographic functionalities including 2-ethyl-2-adamantyl methacrylate (EAdMA), α-gamma-butyrolactone methacrylate (GBLMA), and 3-hydroxy-1-adamantyl methacrylate (HAdMA), were used as monomer components and 2-cyanoprop-2-yl-1-dithionaphthalate (CPDN) was used as the chain transfer agent (CTA). In both polymerizations, the order of monomer reactivity was GBLMA>HAdMA>>EAdMA. This caused a composition gradient in RAFT polymerization as well as composition inhomogeneity in FRP. The polymers prepared by RAFT polymerization had lower molecular weight distributions and more uniform compositions. The improvement in molecular weight distribution and composition uniformity of the polymers prepared by RAFT polymerization should be beneficial for the ArF lithography process.