Reversible Addition-fragmentation Chain Transfer Polymerization Agent Research Articles

A new method for synthesis of modified cellulose‐graft‐poly(acrylic acid) copolymer using 4‐cyano‐4‐[(phenylcarbothioyl)solfanyl]pentanoic acid to serve as RAFT agent

AbstractIn this study, cellulose was first treated with 4‐cyano‐4‐((phenyl carbonothioyl)solfanyl) pentanoic acid to serve as the reversible addition‐fragmentation chain transfer polymerization (RAFT) agent, then the controlled grafting polymerization of acrylic acid was successfully performed. A well‐defined, cellulose‐graft‐acrylic acid copolymer (Cell‐g‐PAA), has been prepared by RAFT polymerization technique using three different approaches: RAFT agent was prepared by substitution of dithiobenzoate magnesium bromide with 4,4'‐azobis(4‐cyanopentanoic acid) in ethyl acetate as a solvent, mediated cellulose (Cell) block as the macromolecular Cell‐RAFT agent and (cellulose‐co‐acrylic acid) copolymer with alternating sequence. The resulting (Cell‐RAFT) for “living” free radical polymerization was then heated in the adjacent acrylic acid monomer for the development of the controlled graft copolymer onto cellulose. The structures of the intermediate, graft copolymer were investigated by FT‐IR, DSC, 1H NMR, scanning electron microscopy, and thermo gravimetric. The results demonstrate that the preparation of graft copolymers was successfully confirmed. This approach would provide an extensive classification of molecular designs to obtain modern types of tailored hybrid materials derived from natural polysaccharides and synthetic polymers. Also, using a macro‐initiator is an excellent method for synthesizing new materials.

Mechanical modification of RAFT-based living polymer networks by photo-growth with crosslinker

Abstract In this work we present a study into the usage of crosslinker growth of Reversible addition-fragmentation chain-transfer polymerization (RAFT)-based Living Polymer Networks (LPNs) for the purpose of mechanical strengthening. Previous work with LPNs has thoroughly covered growth with monomers for various goals, and has touched on using a small amount of crosslinker during growth to retain mechanical strength after growth. Herein, we demonstrate growth with both purely crosslinker and purely monomer for the sake of comparison. We also show this across both symmetries of RAFT agent to see how their different growth behaviors affect the results. The asymmetric RAFT underwent a mesh-filling process during growth which resulted in both crosslinker and monomer strengthening the parent network to a similar degree. However, with the symmetric RAFT agent we saw that the crosslinker and monomer growth caused opposite effects due to their impact on the average crosslinking density; while monomer growth lowered it, growth with crosslinker increased it and strengthened the gel accordingly.

Near-Infrared-Triggered Photothermal Aggregation of Polymer-Grafted Gold Nanorods in a Simulated Blood Fluid.

Gold nanorods were decorated with thermoresponsive copolymers of tailored architecture and constructed from N-isopropyl acrylamide and acrylamide. The copolymers were prepared via reversible addition-fragmentation chain transfer polymerization (RAFT) and immobilized on the gold nanorod surface taking advantage of the aurophilicity of its inherently formed trithiocarbonate groups. The topology as well as the average molecular weight of the copolymers was altered using either a monofunctional or 3-arm star RAFT agent. Two-dimensional arrays of the self-assembled core-shell nanostructures were fabricated by drop-casting showing tunable interparticle spacings. In a simulated blood fluid, the lower critical solution temperature of the nanohybrids could be modified over a significant temperature range around body temperature by adjusting the copolymer composition, the architecture, and/or the size of the polymer. The intrinsic photothermal properties of the gold nanorods were utilized to trigger particle aggregation by irradiation at 808 nm in the optical window of human tissues. In effect, a new nanohybrid system with remotely controllable aggregation via an external NIR-light stimulus for nanomedical applications was developed.

Efficient Heterodifunctional Unimolecular Ring‐Closure Method for Cyclic Polymers by Combining RAFT and SuFEx Click Reactions

A novel ring-closure strategy for cyclic polymers by combining reversible addition-fragmentation chain transfer polymerization (RAFT) and the sulfur(VI)-fluoride exchange (SuFEx) click reaction is presented. Herein, a new heterodifunctional trithiocarbonate RAFT agent, 2-((tert-butyldimethylsilyl)oxy)ethyl (4-(fluorosulfonyl)benzyl) carbonotrithioate (TBDMS-FSBCT), containing both tert-butyldimethylsilyl ether and sulfonyl fluoride moieties, is developed. The polymerization behavior of TBDMS-FSBCT is first demonstrated by a standard RAFT polymerization procedure for two types of vinyl monomers, N-isopropylacrylamide (NIPAAm) (conjugated vinyl monomer) and N-vinylpyrrolidone (NVP) (unconjugated vinyl monomer). The tert-butyldimethylsilyl ether and sulfonyl fluoride groups at the α and ω positions of the obtained linear polymer precursors (L-PNIPAAm and L-PVP) are verified by 1 H, 13 C, and 19 F NMR spectra. Subsequent intramolecular SuFEx click cyclization of the α,ω-heterofunctionalized linear precursors in air at room temperature conveniently yields the corresponding cyclic polymers (C-PNIPAAm and C-PVP). Overall, this is the first report on the preparation of cyclic polymers based on the SuFEx reaction under ambient conditions. It is envisioned that the approach may open an avenue for the formation of cyclic polymers.

Statistical copolymerization of N-vinyl-pyrrolidone and alkyl methacrylates via RAFT: reactivity ratios and thermal analysis

The synthesis of statistical copolymers of N-vinylpyrrolidone (NVP) with the alkyl methacrylates: hexyl methacrylate (HMA) and stearyl methacrylate (SMA), is conducted by reversible addition-fragmentation chain transfer polymerization (RAFT), employing [(O-ethylxanthyl) methyl]benzene and [1-(O-ethylxanthyl) ethyl]benzene as the RAFT agents. The reactivity ratios are estimated using the Fineman-Ross, inverted Fineman-Ross, Kelen-Tudos and Barson-Fenn graphical methods as well as the computer program COPOINT, modified to both the terminal and the penultimate model. In all cases, the NVP reactivity ratio is significantly lower than that of the methacrylates. Structural parameters of the copolymers are obtained by calculating the dyad and triad sequence fractions and the mean sequence length. The thermal properties of the copolymers are studied by Differential Scanning Calorimetry and Thermogravimetric Analysis, and the results are compared with those of the respective homopolymers. In spite of the relatively small amount of NVP in the copolymers, copolymer thermal properties are influenced by both monomers.

Non-ionic fluorinated amphiphilic block copolymer via RAFT polymerization and their application as surfactant in emulsion polymerization

This investigation reports the synthesis of block copolymer of poly(ethylene glycol) methyl ether methacrylate (PPEGMA) with poly(heptafluorobutyl acrylate) (PHFBA). The blockcopolymer was prepared via reversible addition-fragmentation chain transfer polymerization (RAFT). The RAFT end-capped poly[poly(ethylene glycol) methyl ether methacrylate] (PPEGMA) macro-chain transfer agent (CTA) was prepared using 2-cyano-2-propyl dithiobenzoate (CPBT) as RAFT agent. The synthesized PPEGMA was later used as macro-RAFT agent for the polymerization of 2,2,3,3,4,4,4-heptafluorobutyl acrylate (HFBA) which yielded well-defined block copolymers of varied lengths. The PPEGMA-b-PHFBA block copolymer self-assembles in water produces spherical micelles with core-shell nano-structure where the core made of hydrophobic block (PHFBA) and shell is of hydrophilic block (PPEGMA). The synthesized block copolymers, PPEGMA−b−PHFBA, an amphiphilic block copolymers were used as surfactant in the surfactant free emulsion polymerization of styrene. Aqueous micellar solutions of the block copolymers were characterized by DLS and TEM analyses. The CMC value of polymeric surfactant was 0.046 mg. mL−1, determined by surface tension analysis. The block copolymers were characterized by GPC, 1H NMR, FT-IR, DSC analyses.

Statistical copolymers of N-vinylpyrrolidone and benzyl methacrylate via RAFT: Monomer reactivity ratios, thermal properties and kinetics of thermal decomposition

ABSTRACTStatistical copolymers of N-vinylpyrrolidone (NVP) with benzyl methacrylate (BzMA) were prepared by Reversible Addition-Fragmentation chain Transfer Polymerization (RAFT), employing three different xanthates as RAFT agents: [(O-ethylxanthyl)methyl]benzene, [1-(O-ethylxanthyl)ethyl]benzene and O-ethyl S-(phthalimidylmethyl) xanthate. The reactivity ratios were estimated using the Fineman-Ross, inverted Fineman-Ross, Kelen-Tüdos and extended Kelen-Tüdos linear graphical methods, as well as the computer program COPOINT. Structural parameters of the copolymers were obtained by calculating the dyad sequence fractions and the mean sequence length. All the methods are in agreement that the probability for the incorporation of BzMA units is much greater than for that of NVP units. The glass-transition temperature (Tg) values of the copolymers were measured by Differential Scanning Calorimetry and examined by means of several theoretical equations, allowing for the prediction of these Tg values. Subsequently, a systematic and detailed investigation of the thermal degradation of these copolymers compared with that of the respective homopolymers, was carried out by Thermogravimetric Analysis, within the framework of the Ozawa-Flynn-Wall and Kissinger methodologies. As expected, the thermal stability of the copolymers is influenced by the structure of the substituents of the thiocarbonylthio end groups due to the RAFT agents.

Synthesis and Characterization of NBR´s by RAFT Technique and their use as Rubber Precursor in ABS Type Resins

<p>Different rubbers based on polybutadiene were synthesized in solution by the reversible addition-fragmentation chain-transfer polymerization (RAFT) technique using 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl] entanoic acid as RAFT agent and 1,1’-azobiscyclohexanecarbonitrile (Vazo-88) as initiator. The results obtained in the polymerization of polybutadiene and poly(butadiene-<em>co</em>-acrylonitrile) (NBR) are discussed in terms of molecular weight distribution, composition and microstructure. Composition of polybutadiene in NBR´s was kept constant along the copolymerization, and the vinyl, <em>cis</em> and <em>trans</em> isomers are shown in values of around 12, 26 and 62% in all cases. Resulting rubbers were used to synthesize acrylonitrilebutadiene-styrene (ABS) type resins through an <em>in situ</em> bulk polymerization. Dynamic-mechanical properties and the morphology were analyzed in all the different ABS resins. In DMA analyses, the rubber component presented two transitions as well as an increase in the magnitude of the transition located around -75 °C, which is explained by the significant amount of SAN occlusions in the morphology, analyzed by TEM.</p>

Styrenation of air blown linseed oil via RAFT–mediated miniemulsion polymerization

Abstract In this study styrenated oil products were prepared under miniemulsion conditions by reversible addition-fragmentation chain transfer polymerization (RAFT) technique using phenacyl morpholine dithiocarbamate (PMDC) as a RAFT agent. First, hydroperoxide groups were formed on the oil structure by air-blowing process. Then the prepared miniemulsion of air blown linseed oil (ABLO)-styrene mixture was subjected to styrenation in the presence of the RAFT agent. Miniemulsion was prepared by means of ultrasonication by using cetyl trimethyl ammonium bromide (CTAB) and hexadecane (HD) as surfactant and co-surfactant, respectively. The best miniemulsion conditions were determined by a new strategy based on the determination of the conditions ensuring not to change of droplet/particle size throughout the polymerization. In this way, the conditions for the elimination of monomer diffusion between droplets were established. The styrenated oil product obtained under optimum conditions was characterized by FT-IR, 1 H NMR and GPC measurements. In order to understand the effect of miniemulsion conditions on molecular weight and polydispersity index (PDI), styrenated oil samples were also prepared in solvent (dioxane) medium. Tests for film properties of product prepared by RAFT in miniemulsion medium were applied according to related standards. The styrenated oil obtained in this study exhibited molecular weight distribution values lower than styrenated oil products obtained by the classical RAFT polymerization in solvent medium. The film properties showed that these styrenated oil samples could be used as an oil based binder.

Statistical copolymers of N‐vinylpyrrolidone and 2‐(dimethylamino)ethyl methacrylate via RAFT: Monomer reactivity ratios, thermal properties, and kinetics of thermal decomposition

ABSTRACTStatistical copolymers of N‐vinylpyrrolidone (NVP) with 2‐(dimethylamino)ethyl methacrylate (DMAEMA) were prepared by Reversible Addition‐Fragmentation chain Transfer Polymerization (RAFT), employing three different RAFT agents: [(O‐ethylxanthyl)methyl]benzene, [1‐(O‐ethylxanthyl)ethyl]benzene, and O‐ethyl S‐(phthalimidylmethyl) xanthate. The reactivity ratios were estimated using the Fineman‐Ross, inverted Fineman‐Ross, Kelen‐Tüdos, and extended Kelen‐Tüdos graphical methods, along with the computer program COPOINT. Structural parameters of the copolymers were obtained by calculating the dyad sequence fractions and the mean sequence length. All the methods indicate that the DMAEMA reactivity ratio is much greater than the one of NVP, thus, the statistical copolymers are in fact pseudo‐diblocks. The glass‐transition temperature (Tg) values of the copolymers were measured by Differential Scanning Calorimetry. Furthermore, a systematic and detailed investigation has been done, on the thermal degradation of the copolymers compared with the respective homopolymers, by Thermogravimetric Analysis, within the framework of the Ozawa‐Flynn‐Wall and Kissinger methodologies. Apparently, the thermal stability of the copolymers is influenced by both monomers and by the structure of the thiocarbonylthio end groups due to the RAFT agents. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 3776–3787

Molecularly imprinted polymer prepared with polyhedral oligomeric silsesquioxane through reversible addition-fragmentation chain transfer polymerization.

Polyhedral oligomeric silsesquioxane (POSS) was utilized to prepare imprinted polymer through reversible addition-fragmentation chain transfer polymerization (RAFT) successfully. The imprinted polymer was made with a mixture of RAFT agent, 4-vinylpyridine (4-VP), POSS monomer [PSS-(1-propylmethacrylate)-heptaisobutyl substituted, MA 0702], and ethylene glycol dimethacrylate (EDMA), with ketoprofen (KET) as template. The influence of polymerization variables, the amount of RAFT agent and POSS monomer, the ratio of KET to 4-VP, and the ratio of 4-VP to EDMA, were investigated on the retention factor and imprinting effect. The greatest imprinting factor of the RAFT agent-based POSS MIP was 15.2, about 1.5 times higher than the RAFT agent-free agent POSS MIP. The permeability, surface morphology, as well as pore size distribution of POSS MIP monoliths made with RAFT agent and without RAFT agent were also studied. The optimal MIP was applied to solid phase extraction for KET from commercial tablets. The mean recoveries of KET for RAFT-based POSS MIP was 85.2% with a relative standard deviation of 2.6%.

Grafting of diallyldimethylammonium chloride on graphene oxide by RAFT polymerization for modification of nanocomposite polysulfone membranes using in water treatment

In this study, functionalized grapheme oxide (GO) was utilized as an additive for the preparation of nanocomposite membrane. For growing the polymer chains on the graphene oxide surface, the control living radical polymerization (reversible addition fragmentation chain transfer polymerization (RAFT) technique), was applied. The RAFT agent, O-ethyl xanthate was grafted on the grapheme oxide surface and then the chains of PDADMAC grew from modified sites. GO-PDADMAC was investigated by FTIR, HNMR, FESEM, TGA and DSC techniques. The effect of GO-PDADMAC on the morphology and surface property of the polysulfone (PSf) membranes was examined using scanning electron microscopy (FESEM) and atomic force microscopy (AFM). The contact angle (CA), pure water flux (PWF) and antifouling properties of modified membranes were also used to investigate the membranes performance. The results suggested that the water flux of membrane increased to 443.22Lm−2h−1 which related to 7wt% GO-PDADMAC/20% PSf membrane as well as the highest rejection for different heavy metals, namely Cu2+ (86.68%), and Cd2+ (88.68%) assigned to 5wt% GO-PDADMAC/20% PSf and 3wt% GO-PDADMAC/23% PSf, membranes, respectively.

Fabrication of mPEGylated graphene oxide/poly(2‐dimethyl aminoethyl methacrylate) nanohybrids and their primary application for small interfering RNA delivery

ABSTRACTGraphene oxide (GO)‐based nanohybrids were designed for small interfering RNA (siRNA) delivery for their high water dispensability, good biocompatibility, easily tunable surface functionalization, and particular optical properties. In this study, novel nanohybrids based on GO were fabricated. Methoxypoly(ethylene glycol) (mPEG) was covalently conjugated to GO via amide bonds. Then, poly(2‐dimethyl aminoethyl methacrylate) (PDMAEMA), which was synthesized via reversible addition–fragmentation chain transfer polymerization (RAFT) with 2‐(dodecyl thiocarbonothioyl thio)‐2‐methyl propionic acid (DTM) as the RAFT agent, was attached onto GO via physical interaction between DTM and GO. Compared with Lipofectamine 2000, the novel mPEG–GO/PDMAEMA nanohybrids showed comparable gene transfection efficiency and a low cytotoxicity. Moreover, the mPEG–GO/PDMAEMA nanohybrids showed enhanced optical properties compared to the original GO because of the presence of mPEG and PDMAEMA. Our work encouraged further exploration of the novel nanovector for combined photothermal and siRNA delivery. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43303.

Synthesis and Characterization of Four‐Arm Star Polystyrene Based on a Novel Tetrafunctional RAFT Agent

Reversible addition fragmentation chain transfer polymerization (RAFT) is a very versatile polymerization technique whereby the topology of the final polymer can be tailored using specific RAFT agents. The tetrafunctional RAFT agent, tetrabenzyl(1,3‐dithietane‐2,2,4,4‐tetrayl)­tetracarbanotrithioate, has not previously been used to synthesize polymers. Poly­styrene (PS) is synthesized using this tetrafunctional RAFT agent and advanced characterization is performed using spectroscopic and separation methods. In situ 1H nuclear magnetic resonance spectroscopy (NMR) and size‐exclusion chromatography (SEC) are used to determine the topology of the resultant PS. The polymerization is followed by in situ 1H NMR, using styrene‐d8 rather than hydrogenous styrene. In situ 1H NMR spectra show that the RAFT agent is incorporated into the polymer as a terminal group. Aminolysis of the star‐shaped PS is performed and the SEC and NMR results before and after aminolysis are compared. These results indicate that the expected star‐shaped topology of the polymer is achieved. image

Reversible addition‐fragmentation chain transfer polymerization of vinyl acetate under high pressure

ABSTRACTIn this work, high molecular weight polyvinyl acetate (PVAc) (Mn,GPC = 123,000 g/mol, Mw/Mn = 1.28) was synthesized by reversible addition‐fragmentation chain transfer polymerization (RAFT) under high pressure (5 kbar), using benzoyl peroxide and N,N‐dimethylaniline as initiator mediated by (S)‐2‐(ethyl propionate)‐(O‐ethyl xanthate) (X1) at 35 °C. Polymerization kinetic study with RAFT agent showed pseudo‐first order kinetics. Additionally, the polymerization rate of VAc under high pressure increased greatly than that under atmospheric pressure. The “living” feature of the resultant PVAc was confirmed by 1H NMR spectroscopy and chain extension experiments. Well‐defined PVAc with high molecular weight and narrow molecular weight distribution can be obtained relatively fast by using RAFT polymerization at 5 kbar. © 2015 Wiley Periodicals, Inc. J. Polym. Sci. Part A: Polym. Chem. 2015, 53, 1430–1436

Preparation of PMAM-B-PNVP and its Hydrolysate by RAFT Polymerization: Structure Characterization and its CO<sub>2</sub> Permeation Performance

Macromolecules chain transfer agents (MCTA) were synthesized through the reversible addition fragmentation chain transfer polymerization (RAFT) by using S-l-Dodecyl-S′-(α, α′-dimethyl-α-acetic acid) trithiocarbonate(MTTCD), S, S′-bis (2-hydroxyethyl-2′-dimethylacrylate) trihiocarbonate (BDATC), 2-cyanoprop-2-yl dithiobenzoate (CPDB) as the chain transfer agents, methacrylamide (MAM) as the first polymerization monomer. The results showed that the structures of the end-group of dithiocarbamates had significant effects on the activity of dithiocarbamates for the polymerization of PMAM. The derived block copolymer (PMAM-b-PNVP) was prepared by using the above mentioned polymer as macromolecular RAFT agent and NVP as the second polymerization monomer. N-vinyl-γ-sodium aminobutyrate-sodium methacrylate copolymer (VSA-MSA) containing -NH2 and -COOH as the CO2 facilitated carrier, a kind of new fixed carrier membrane material for CO2 separation, was synthesized by hydrolysis of the resulted PMAM-b-PNVP. The chemical composition and structure of PMAM-CTA, PMAM-b-PNVP, MSA-VSA were analyzed by FTIR, 1HNMR and DSC, the molecular weight and polydispersity index were analyzed by GPC. The Relative molecular mass of polymer was controllable. The polydispersity index (1.2~1.3) of the obtained polymer was narrow via using MTTCD and BDATC. The VSA-MSA/PS composite membranes were prepared. The CO2 and N2 permeation performance were tested at different pressure. The results showed that the resulted composited membrane had a CO2 permeation rate of 1.2×10-4 cm3 (STP) cm-2s-1cmHg-1 and a N2 permeation rate of 8.57×10-7 cm3 (STP) cm-2s-1cmHg-1 and an ideal CO2/ N2 selectivity of 140.02 at a feed gas pressure of 7.6 cmHg and 30 °C.

Pushing the mechanical strength of PolyHIPEs up to the theoretical limit through living radical polymerization

High internal phase emulsion (HIPE) living polymerization was proposed in current work. Reversible addition-fragmentation chain transfer polymerization (RAFT), one of the living radical polymerization methods, was introduced to the polymerization of HIPE for the preparation of polystyrene PolyHIPEs. Living polymerization changed the crosslinking process giving a highly homogeneous polymeric wall of PolyHIPEs. The resolving of the heterogeneity problem increased the mechanical strength of PolyHIPEs significantly with the Young's modulus reaching the theoretical value of ∼45 MPa, which was more than 3 times higher than that by the conventional method. Not only the open-cellular structure of PolyHIPEs was maintained but also a higher connectivity was achieved. Both the type and the concentration of RAFT agents were found to have influence on the morphology and mechanical strength of PolyHIPEs.

Using dilatometry in the reversible addition fragmentation transfer polymerization of N-(S)-(−)-α-methylbenzyl methacryloylamine

Optically active polymers were prepared using reversible addition-fragmentation chain transfer polymerization (RAFT) of N-(S)-α-methylbenzylmethacryloylamine (N-(S)-α-MBMA), a functional optically active monomer. RAFT polymerizations were carried out at 70 °C in ethanol using AIBN as a thermal initiator and benzyl or (1-phenyl)ethyl dithiobenzoate (BDB and PEDB, respectively) as the RAFT agents. The kinetic study was performed by dilatometry. Plots of conversion vs time indicated that the polymerizations followed first order kinetics. 1H NMR, IR, and UV–vis spectrophotometric studies confirmed the presence of thiocarbonylthio moieties (−SCS-) in the polymer chains. The molecular weight distributions (MWDs) were moderately narrow with polydispersity indices between 1.3 and 1.6, which indicated that the control of the reaction was not completely achievement using BDB or PEDB as RAFT agents. The optical activity [α]D25 measurements of synthesized polymers by RAFT did not show a noticeably linear increase dependence with respect to molecular weight, as was previously reported for another controlled free radical polymerization (CRP) system.

Production of oil-based binder by RAFT polymerization technique

In this study, air-blown linseed oil was styrenated by reversible addition–fragmentation chain transfer polymerization (RAFT). For this purpose, hydroperoxide groups were formed in the structure of linseed oil by blowing air through it. The oxidized oil was used as a macroinitiator in the styrenation process by RAFT technique using phenacyl morpholine dithiocarbamate (PMDC) as a RAFT agent. The obtained samples were characterized by GPC and FT-IR measurements. The effects of various parameters, such as the amount of PMDC, the number of peroxide groups, and the reaction time were investigated on polydispersity and molecular weight. For comparison, a copolymer sample was also prepared in the absence of PMDC. The film properties of all the samples were determined according to the related standards and compared. The sample obtained by the RAFT technique exhibited better film properties and a relatively narrow polydispersity, showing that the RAFT technique provides good control over the polymerization system in this study.

Novel Degradable Polymer Networks Containing Acetal Components and Well-Defined Backbones

A novel copolymer network was successfully prepared by combining the reversible addition–fragmentation chain-transfer polymerization (RAFT) and addition reaction between hydroxyl and vinyloxy groups. 2-Hydroxyethyl methacrylate (HEMA) and methyl methacrylate (MMA) were copolymerized in 1,4-dioxane with 2,2′-azobisisobutyronitrile as initiator and 2-(ethoxycarbonyl)prop-2-yl dithiobenzoate as a RAFT agent. The molecular weight of poly(HEMA-co-MMA) was well controlled and the polydispersity was low. The hydroxyl group from the HEMA unit in the copolymer underwent an addition reaction with 1,4-cyclohexanedimethanol divinyl ether in the presence of pyridinium p-toluenesulfonate, generating a copolymer network with an acetal component in the crosslinking segment. The crosslinking time depended on the molar ratio of HEMA and MMA in the poly(HEMA-co-MMA). After being treated in strong acid, the copolymer network was able to be degraded owing to the acetal structure, but the backbone chains of poly(HEMA-co-MMA) remained intact.