Thermosensitive polymer structures based on segmented copolymer networks

Segmented polymer networks with LCST‐behavior have been prepared by free radical initiated copolymerization of α,ω‐bis‐methacrylate terminated poly(methyl vinyl ether) (PMVE) with 2‐hydroxy ethyl methacrylate (HEMA) or butyl acrylate (BA). The PMVE bis‐macromonomers have been obtained via a semi‐continuous process by end‐capping the living cationic polymerization of methyl vinyl ether (MVE) with HEMA. The phase separation temperature can be varied by changing the PMVE/comonomer ratio. Incorporation of PMVE‐grafts in the hydrogels increases the rate of deswelling and improves the mechanical properties. The application of the segmented networks for thermo‐controllable solid phase extraction has been demonstrated by their thermosensitive adsorption behavior of toluene from a water solution.     

Poly(vinyl ethers) as building blocks for new materials

The living cationic polymerization of vinyl ethers has been used to prepare a number of new polymers with special properties. Sequential polymerization of the hydrophilic methyl vinyl ether (MVE) and the hydrophobic octadecyl vinyl ether (ODVE) has lead to amphiphilic block-copolymers with emulsifying properties for water/decane mixtures. Poly(vinyl-ether) macromonomers were obtained by end-capping of living polymers with hydroxyethyl acrylate. Copolymerization of polyODVE-macromonomer with usual acrylates lead to highly branched hydrophobic polymers. When the end-capping was performed with bifunctionally living polymers, the corresponding “bis-macromonomers” were obtained. Copolymerization of such bis-macromonomers with styrene or butyl acrylate, leads to the formation of segmented polymer networks. In the case of polyODVE-poly(butyl acrylate), these networks showed a pronounced phase separation. Due to the crystallinity of the polyODVE domains, these materials showed shape memory properties.     

Stimuli‐responsive reversible physical networks. I. Synthesis and physical network properties of amphiphilic block and random copolymers with long alkyl chains by living cationic polymerization

The living cationic polymerization of octadecyl vinyl ether (ODVE) was achieved with an 1‐(isobutoxy)ethyl acetate [CH₃CH(OiBu)OCOCH₃]/EtAlCl₂ initiating system in hexane in the presence of an added weak Lewis base at 30 °C. In contrast to conventional polymers, poly(octadecyl vinyl ether) underwent upper‐critical‐solution‐temperature‐type phase separation in various solvents, such as hexane, toluene, CH₂Cl₂, and tetrahydrofuran, because of the crystallization of octadecyl chains. Amphiphilic block and random copolymers with crystallizable substituents of ODVE and 2‐methoxyethyl vinyl ether (MOVE) were synthesized via living cationic polymerization under similar conditions. Aqueous solutions of the copolymers yielded physical gels upon cooling because of strong interactions between ODVE units, regardless of the copolymer structure. The product gels, however, exhibited different viscoelastic properties: A 20 wt % solution of a block copolymer (400/20 MOVE/ODVE) became a soft physical gel that behaved like a typical gel, whereas the corresponding random copolymer gave a transparent but stiff gel with a certain relaxation time. Differential scanning calorimetry analysis confirmed that the crystalline–amorphous transition of the octadecyl chains was a key step for inducing such physical gelation. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1155–1165, 2005     

Synthesis of various stimuli‐responsive gradient copolymers by living cationic polymerization and their thermally or solvent induced association behavior

Stimuli‐responsive gradient copolymers, composed of various monomers, were synthesized by living cationic polymerization in the presence of base. The monomers included thermosensitive 2‐ethoxyethyl vinyl ether (EOVE) and 2‐methoxyethyl vinyl ether (MOVE), hydrophobic isobutyl vinyl ether (IBVE) and 2‐phenoxyethyl vinyl ether (PhOVE), crystalline octadecyl vinyl ether (ODVE), and hydrophilic 2‐hydroxyethyl vinyl ether (HOVE). The synthesis of gradient copolymers was conducted using a semibatch reaction method. Living cationic polymerization of the first monomer was initiated using a conventional syringe technique, followed by an immediate and continuous addition of a second monomer using a syringe pump at regulated feed rates. This simple method permitted precise control of the sequence distribution of gradient copolymers, even for a pair of monomers with very different relative monomer reactivities. The stimuli‐responsive gradient, block and random copolymers exhibited different self‐association behavior. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6444–6454, 2008     

Stimuli‐responsive reversible physical networks. II. Design and properties of homogeneous physical networks consisting of periodic copolymers synthesized by living cationic polymerization

The design and precision synthesis of physical networks consisting of copolymers with crystallizable pendant groups are described in this work. Amphiphilic periodic, statistical, and gradient copolymers consisting of octadecyl vinyl ether (ODVE) units were synthesized via living cationic polymerization. The synthesis involved the copolymerization of ODVE and 2‐methoxyethyl vinyl ether (hydrophilic) with an 1‐(isobutoxy)ethyl acetate [CH₃CH(OiBu)OCOCH₃]/Et_1.5AlCl_1.5 initiating system in the presence of a weak Lewis base to yield copolymers with very narrow molecular weight distributions (weight‐average molecular weight/number‐average molecular weight ? 1.2). All aqueous solutions of the copolymers behaved as a viscous liquid above 50 °C. When cooled below 25 °C, the solutions turned into transparent, transient physical gels (exhibiting terminal flow), regardless of the sequence distribution. Viscoelastic studies showed that a periodic copolymer gave a hard gel that was more brittle than the gels obtained from the corresponding statistical and gradient copolymers. This difference and the differences in the relaxation time and relaxation mode distribution of the copolymer gels were consistent with the sequence distributions of ODVE in the respective copolymers. These results indicate that the mechanical properties of a physical network can be controlled by the primary polymer structures. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2712‐2722, 2005     

Synthesis of biocompatible and biodegradable block copolymers of polyvinyl alcohol‐block‐poly(ε‐caprolactone) using metal‐free living cationic polymerization

Applications of metal‐free living cationic polymerization of vinyl ethers using HCl · Et₂O are reported. Product of poly(vinyl ether)s possessing functional end groups such as hydroxyethyl groups with predicted molecular weights was used as a macroinitiator in activated monomer cationic polymerization of ε‐caprolactone (CL) with HCl · Et₂O as a ring‐opening polymerization. This combination method is a metal‐free polymerization using HCl · Et₂O. The formation of poly(isobutyl vinyl ether)‐b‐poly(ε‐caprolactone) (PIBVE‐b‐PCL) and poly(tert‐butyl vinyl ether)‐b‐poly(ε‐caprolactone) (PTBVE‐b‐PCL) from two vinyl ethers and CL was successful. Therefore, we synthesized novel amphiphilic, biocompatible, and biodegradable block copolymers comprised polyvinyl alcohol and PCL, namely PVA‐b‐PCL by transformation of acid hydrolysis of tert‐butoxy moiety of PTBVE in PTBVE‐b‐PCL. The synthesized copolymers showed well‐defined structure and narrow molecular weight distribution. The structure of resulting block copolymers was confirmed by ¹H NMR, size exclusion chromatography, and differential scanning calorimetry. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5169–5179, 2009     

Polymer networks containing crystallizable poly(octadecyl vinyl ether) segments for shape‐memory materials

New polymer networks were prepared by free radical initiated copolymerization of crystallizable α,ω‐bismethacrylate‐terminated poly(octadecyl vinyl ether) (polyODVE) with butyl acrylate (BA). The polyODVE bismacromonomers were obtained by end‐capping the bifunctionally living cationic polymerization of ODVE with 2‐hydroxyethyl methacrylate (HEMA). The segmented networks show a high degree of phase separation over a wide range of compositions. The shape memory properties of a material containing 20 wt.‐% of polyODVE are reported.     

Cationic RAFT Polymerization Using ppm Concentrations of Organic Acid

A metal‐free, cationic, reversible addition–fragmentation chain‐transfer (RAFT) polymerization was proposed and realized. A series of thiocarbonylthio compounds were used in the presence of a small amount of triflic acid for isobutyl vinyl ether to give polymers with controlled molecular weight of up to 1×10⁵ and narrow molecular‐weight distributions (M_w/M_n<1.1). This “living” or controlled cationic polymerization is applicable to various electron‐rich monomers including vinyl ethers, p‐methoxystyrene, and even p‐hydroxystyrene that possesses an unprotected phenol group. A transformation from cationic to radical RAFT polymerization enables the synthesis of block copolymers between cationically and radically polymerizable monomers, such as vinyl ether and vinyl acetate or methyl acrylate.     

Thermosensitive polyalcohols: Synthesis via living cationic polymerization of vinyl ethers with a silyloxy group

Thermosensitive homopolymers and copolymers with hydroxy groups were synthesized via the living cationic polymerization of Si‐containing vinyl ethers. The cationic homopolymerization and copolymerization of five vinyl ethers with silyloxy groups, each with a different spacer length, were examined with a cationogen/Et_1.5AlCl_1.5 initiating system in the presence of an added base. When an appropriate base was added, the living cationic polymerization of Si‐containing monomers became feasible, giving polymers with narrow molecular weight distributions and various block copolymers. Subsequent desilylation gave well‐defined polyalcohols, in both water‐soluble and water‐insoluble forms. One of these polyalcohols, poly(4‐hydroxybutyl vinyl ether), underwent lower‐critical‐solution‐temperature‐type thermally induced phase separation in water at a critical temperature (T_PS) of 42 °C. This phase separation was quite sensitive and reversible on heating and cooling. The phase separation also occurred sensitively with random copolymers of thermosensitive and hydrophilic or hydrophobic units, the T_PS values of which in water could be controlled by the monomer feed ratio. The thermal responsiveness of this polyalcohol unit made it possible to prepare novel thermosensitive block and random copolymers consisting solely of alcohol units. One example prepared in this study was a 20 wt % aqueous solution of a diblock copolymer consisting of thermosensitive poly(4‐hydroxybutyl vinyl ether) and water‐soluble poly(2‐hydroxyethyl vinyl ether) segments, which transformed into a physical gel above 42 °C. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3300–3312, 2003     

Syntheses of amphiphilic block copolymers by living cationic polymerization of vinyl ethers and their selective solvent‐induced physical gelation

Amphiphilic diblock copolymers were prepared by the living cationic polymerization of vinyl ethers in the presence of added bases, and their selective solvent‐induced physical gelation behavior was investigated. The block copolymerization of 2‐phenoxyethyl vinyl ether (PhOVE) and 2‐methoxyethyl vinyl ether (MOVE) was carried out in the presence of ethyl acetate with Et_1.5AlCl_1.5 in toluene at 0 °C. Despite the rate difference, diblock copolymers with a very narrow molecular weight distribution were obtained, quantitatively. By adding the selective solvent, water, to the acetone solution of the diblock copolymer, PhOVE₂₀₀‐b‐MOVE₄₀₀, physical gelation occurred suddenly and the system ceased to flow, maintaining transparency. Viscoelastic measurements and transmission electron microscopic observations were performed to examine the characteristic gelation behavior and structure of the obtained gels. Various gelation conditions and physical gelation by other amphiphilic block copolymers were also designed on the basis of the solubility of each block segment. Further, new forms of physical gelation, accompanied by the solubilization of immiscible organic compounds, were achieved using similar diblock copolymers. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3190–3197, 2001     

Controlled random and alternating copolymerization of (meth)acrylates,acrylonitrile, and (meth)acrylamides with vinyl ethers by organotellurium‐, organostibine‐, and organobismuthine‐mediated living radical polymerization reactions

Random and alternating copolymerizations of acrylates, methacrylates, acrylonitorile, and acrylamides with vinyl ethers under organotellurium‐, organostibine‐, and organobismuthine‐mediated living radical polymerization (TERP, SBRP, and BIRP, respectively) have been studied. Structurally well‐controlled random and alternating copolymers with controlled molecular weights and polydispersities were synthesized. The highly alternating copolymerization occurred in a combination of acrylates and vinyl ethers and acrylonitorile and vinyl ethers by using excess amount of vinyl ethers over acrylates and acrylonitorile. On the contrary, alternating copolymerization did not occur in a combination of acrylamides and vinyl ethers even excess amount of vinyl ethers were used. The reactivity of polymer‐end radicals to a vinyl ether was estimated by the theoretical calculations, and it was suggested that the energy level of singly occupied molecular orbital (SOMO) of polymer‐end radical species determined the reactivity. By combining living random and alternating copolymerization with living radical or living cationic polymerization, new block copolymers, such as (PBA‐alt‐PIBVE)‐block‐(PtBA‐co‐PIBVE), PBA‐block‐(PBA‐alt‐PIBVE), and (PTFEA‐alt‐PIBVE)‐block‐PIBVE, with controlled macromolecular structures were successfully synthesized. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Star‐shaped cyclopolymers: A new category of star polymer with rigid cyclized arms prepared by controlled cationic cyclopolymerization and subsequent microgel formation of divinyl ethers

The combination of living/controlled cationic cyclopolymerization and crosslinking polymerization of bifunctional vinyl ethers (divinyl ethers) was applied to the synthesis of core‐crosslinked star‐shaped polymers with rigid cyclized arms. Cyclopolymerization of 4,4‐bis(vinyloxymethyl)cyclohexene ( 1 ), a divinyl ether with a cyclohexene group, was investigated with the hydrogen chloride/zinc chloride (HCl/ZnCl₂) initiating system in toluene at 0 °C. The reaction proceeded quantitatively to give soluble poly( 1 )s in organic solvents. The content of the unreacted vinyl groups in the produced polymers was less than ～3 mol%, and therefore, the degree of cyclization of the polymers was determined to be ～97%. The number‐average molecular weight (M_n) of the polymers increased in direct proportion to monomer conversion and further increased on addition of a fresh monomer feed to the almost completely polymerized reaction mixture, indicating that living cyclopolymerization of 1 occurred. The chain linking reactions among the formed living cyclopolymers with 1,4‐bis(vinyloxy)cyclohexane ( 3 ) as a crosslinker in toluene at 0 °C produced core‐crosslinked star‐shaped cyclopoly( 1 )s [star‐poly( 1 )s] in high yield (100%). Dihydroxylation of the cyclohexene double bonds of star‐poly( 1 ) gave hydrophilic water‐soluble star‐shaped polymers with rigid arm structure [star‐poly( 1 )‐OH] with thermo‐responsive function in water. T_gs of star‐poly( 1 ) and star‐poly( 1 )‐OH were 135 °C and 216 °C, respectively; these values are very high as vinyl ether‐based star‐shaped polymers. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1094–1102     

Water-soluble ABC triblock copolymers based on vinyl ethers: Synthesis by living cationic polymerization and solution characterization

Water-soluble ABC triblock copolymers of methyl vinyl ether (MVE), ethyl vinyl ether (EVE), and methyl tri(ethylene glycol) vinyl ether (MTEGVE) of various block sequences and carrying 20 monomer units in each block were synthesized by living cationic polymerization. In addition to the triblocks, one AB diblock, one BA diblock, and one statistical copolymer of MVE and MTEGVE carrying 20 units of each type of monomer were synthesized as controls. Moreover, three homopolymers each carrying 20 units of MVE and end groups of varying hydrophobicity were synthesized using three different initiators. The molecular weights and molecular weight distributions of all the polymers were determined by gel permeation chromatography (GPC) in tetrahydrofuran (THF). The number average degrees of polymerization (DP_ns) and composition of all the polymers were calculated by proton nuclear magnetic resonance (¹H-NMR) spectroscopy. The molecular weights and degrees of polymerization corresponded to the values expected from the monomer/initiator ratios. The calculated polydispersities were reasonably narrow at 1.3. Aqueous GPC studies at room temperature on the triblock copolymers showed that the polymers exist as isolated chains (unimers) in solution but they tend to assemble and form micelles in the presence of a sufficiently high salt concentration apparently due to the insolubility of the EVE units under the latter conditions. Triblocks with a different block sequence exhibited a different susceptibility to salt-induced micellization, as indicated by the retention volume of the micelles and the relative micelle/unimer peak areas. Similarly, the cloud points of the triblock copolymers covered a relatively wide temperature range from 56 to 72°C. These differences in micellization and cloud points suggest a profound effect of the location of the hydrophilic MTEGVE block on copolymer association. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1181–1195, 1997     

The α-halogeno ether function: formation and use in the design of tailor-made polymers

α-Halogeno ether species, in appropriate conditions, can induce the “living” cationic polymerization of vinyl ethers. They can also be used as initiators for the “living” polymerization of styrene derivatives. Therefore, their use as intermediates in the preparation of tailor-made polymers and copolymers offers interesting opportunities in macromolecular synthesis. The main parameters which determine and control their reactivity are reviewed and discussed. The possibility to generate quantitatively these derivatives by various routes and from different organic functions such as aldehyde, ketone, acetal and hydroxyl is examined. Some of these routes have been used to generate the α-halogeno ether function directly at the end of acetal and hydroxy-terminated polymers. The latter have then been used as macroinitiators to prepare new block copolymers. The synthesis of poly(isobutyl vinyl ether-β-ethyl vinyl ether), poly(styrene-β-chloroethyl vinyl ether) and poly(chloroethyl vinyl ether-β-butadiene-β-chloroethyl vinyl ether) by this technique is described.     

Synthesis and characterization of block copolymers containing poly(di(ethylene glycol) 2‐ethylhexyl ether acrylate) by reversible addition–fragmentation chain transfer polymerization

Reversible addition–fragmentation chain transfer (RAFT) polymerization has emerged as one of the important living radical polymerization techniques. Herein, we report the polymerization of di(ethylene glycol) 2‐ethylhexyl ether acrylate (DEHEA), a commercially‐available monomer consisting of an amphiphilic side chain, via RAFT by using bis(2‐propionic acid) trithiocarbonate as the chain transfer agent (CTA) and AIBN as the radical initiator, at 70 °C. The kinetics of DEHEA polymerization was also evaluated. Synthesis of well‐defined ABA triblock copolymers consisting of poly(tert‐butyl acrylate) (PtBA) or poly(octadecyl acrylate) (PODA) middle blocks were prepared from a PDEHEA macroCTA. By starting from a PtBA macroCTA, a BAB triblock copolymer with PDEHEA as the middle block was also readily prepared. These amphiphilic block copolymers with PDEHEA segments bearing unique amphiphilic side chains could potentially be used as the precursor components for construction of self‐assembled nanostructures. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5420–5430, 2007     

Synthesis of ABA‐triblock and star‐diblock copolymers with poly(2‐adamantyl vinyl ether) and poly(n‐butyl vinyl ether) segments: New thermoplastic elastomers composed solely of poly(vinyl ether) backbones

ABA‐type triblock copolymers and AB‐type star diblock copolymers with poly(2‐adamantyl vinyl ether) [poly(2‐AdVE)] hard outer segments and poly(n‐butyl vinyl ether) [poly(NBVE)] soft inner segments were synthesized by sequential living cationic copolymerization. Although both the two polymer segments were composed solely of poly(vinyl ether) backbones and hydrocarbon side chains, they were segregated into microphase‐separated structure, so that the block copolymers formed thermoplastic elastomers. Both the ABA‐type triblock copolymers and the AB‐type star diblock copolymers exhibited rubber elasticity over wide temperature range. For example, the ABA‐type triblock copolymers showed rubber elasticity from about ?53 °C to about 165 °C and the AB‐type star diblock copolymer did from about ?47 °C to 183 °C with a similar composition of poly(2‐AdVE) and poly(NBVE) segments in the dynamic mechanical analysis. The AB‐type star diblock copolymers exhibited higher tensile strength and elongation at break than the ABA‐type triblock copolymers. The thermal decomposition temperatures of both the block copolymers were as high as 321–331 °C, indicating their high thermal stability. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Synthesis of poly(vinyl ether)‐based,ABA triblock‐type thermoplastic elastomers with functionalized soft segments and their gas permeability

The ABA‐type triblock copolymers consisting of poly(2‐adamantyl vinyl ether) [poly(2‐AdVE)] as outer hard segments and poly(6‐acetoxyhexyl vinyl ether) [poly(AcHVE)], poly(6‐hydroxyhexyl vinyl ether) [poly(HHVE)], or poly(2‐(2‐methoxyethoxy)ethyl vinyl ether) [poly(MOEOVE)] as inner soft segments were synthesized by sequential living cationic polymerization. Despite the presence of polar functional groups such as ester, hydroxyl, and oxyethylene units in their soft segments, the block copolymers formed elastomeric films. The thermal and mechanical properties and morphology of the block copolymers showed that the two polymer segments of these triblock copolymers were segregated into microphase‐separated structure. Effect of the functional groups in the soft segments on gas permeability was investigated as one of the characteristics of the new functional thermoplastic elastomers composed solely of poly(vinyl ether) backbones. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1114–1124     

Expanding vinyl ether monomer repertoire for ring-expansion cationic polymerization: Various cyclic polymers with tailored pendant groups

Herein, we clarified the ring-expansion cationic polymerization with a cyclic hemiacetal ester (HAE)-based initiator was versatile in terms of applicable vinyl ether monomers. Although there was a risk that higher reactive vinyl ethers may incur β-H elimination of the HAE-based cyclic dormant species to irreversibly give linear chains, the polymerizations were controlled to give corresponding cyclic polymers from various alkyl vinyl ethers of different reactivities. Functional vinyl ether monomers were also available, and for instance a vinyl ether monomer carrying an initiator moiety for metal-catalyzed living radical polymerization in the pendant allowed construction of ring-linear graft copolymers through the grafting-from approach. Furthermore, ring-based gel was prepared via the addition of divinyl ether at the end of the ring-expansion polymerization, where multi HAE bonds cyclic polymers or fused rings were crosslinked with each other. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3082–3089     

Living cationic polymerization of n‐butyl propenyl ether

Cationic polymerization of n‐butyl propenyl ether (BuPE; CH₃CH CHOBu, cis/trans = 64/36) was examined with the HCl–IBVE (isobutyl vinyl ether) adduct/ZnCl₂ initiating system at −15 ∼ −78 °C in nonpolar (hexane, toluene) and polar (dichloromethane) solvents, specifically focusing on the feasibility of its living polymerization. In contrast to alkyl vinyl ethers, the living nature of the growing species in the BuPE polymerization was sensitive to polymerization temperature and solvent. For example, living cationic polymerization of IBVE can be achieved even at 0 °C with HCl–IBVE/ZnCl₂, whereas for BuPE whose β‐methyl group may cause steric hindrance ideal living polymerization occurred only at −78 °C. Another interesting feature of this polymerization is that the polymerization rate in hexane is as large as in dichloromethane, much larger than in toluene. A new method in determining the ratio of the living growing ends to the deactivated ones was developed with a devised monomer‐addition experiments, in which IBVE that can be polymerized in a living fashion below 0 °C was added to the almost completely polymerized solution of BuPE. The amount of the deactivated chain ends became small in hexane even at −40 °C in contrast to other solvents. Thus hexane turned out an excellent solvent for living cationic polymerization of BuPE. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 229–236, 2000     

Living cationic polymerization of dihydrofuran and its derivatives

Cationic polymerization of 2,3‐dihydrofuran (DHF) and its derivatives was examined using base‐stabilized initiating systems with various Lewis acids. Living cationic polymerization of DHF was achieved using Et_1.5AlCl_1.5 in toluene in the presence of THF at 0 °C, whereas it has been reported that only less controlled reactions occurred at 0 °C. Monomer‐addition experiments of DHF and the block copolymerization with isobutyl vinyl ether demonstrated the livingness of the DHF polymerization: the number–average molecular weight of the polymers shifted higher with low polydispersity as the polymerization proceeded after the monomer addition. Furthermore, this base‐stabilized cationic polymerization system allowed living polymerization of ethyl 1‐propenyl ether and 4,5‐dihydro‐2‐methylfuran at ?30 and ?78 °C, respectively. In the polymerization of 2,3‐benzofuran, the long‐lived growing species were produced at ?78 °C. The obtained polymers have higher glass transition temperatures compared to poly(acyclic alkyl vinyl ether)s. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4495–4504, 2008