Star-shaped polymers by living cationic polymerization. VII. Amphiphilic graft polymers of vinyl ethers with hydroxyl groups: Synthesis and host–guest interaction

Amphiphilic graft polymers of vinyl ethers (VEs) ( 6 ) where each branch consists of a hydrophilic polyalcohol and a hydrophobic poly(alkyl vinyl ether) segment were prepared on the basis of living cationic polymerization, and their properties and functions were compared with the corresponding amphiphilic star-shaped polymers. In toluene at ?15°C, the HI/ZnI₂-initiated living block polymer 2 of an ester-containing VE (CH₂? CHOCH₂CH₂OCOCH₃) and isobutyl VE (IBVE) was terminated with the diethyl 2-(vinyloxy)ethylmalonate anion [ 3 ; ^ΦC(COOEt)₂CH₂CH₂OCH ? CH₂] ( 2/3 = 1/2 mole ratio) to give a macromonomer ( 4 ), H[CH₂CH(OCH₂CH₂OCOCH₃)] _m-[CH₂CH(OiBu)]_n? C(COOEt)₂CH₂CH₂OCH ? CH₂ (m = 5, n = 15; M?_n = 2600, M?_w/M?_n = 1.13, 1.10 vinyl groups/chain). Subsequently, 4 was homopolymerized with HI/ZnI₂ in toluene at ?15°C. In 3 h, 85% of 4 was consumed and a graft polymer ( 5 ) was obtained [M?_w = 15000, DP_n (for 4 ) = 6]. The apparent M?_w (10,900) of 5 by size-exclusion chromatography (SEC) is smaller than that by light scattering as well as that (18,300) by SEC of the corresponding linear polymer with the almost same molecular weight, indicating the formation of a multi-branched structure. Hydrolysis of the pendant esters in 5 gave the amphiphilic graft polymer 6 where each branch consists of a hydrophilic polyalcohol and a hydrophobic poly(IBVE) segment. The graft polymer 6 was found to interact specifically with small organic molecules (guests) with polar functional groups, and 6 differed in solubility and host-guest interaction from the corresponding star-shaped polymer. © 1993 John Wiley & Sons, Inc.     

Synthesis of highly water soluble C60 end‐capped vinyl ether oligomers with well‐defined structure

Highly water soluble [60]fullerene (C₆₀) end‐capped vinyl ether (VE) oligomers with well‐defined structure were synthesized by living cationic polymerization technique. The addition reaction between 1‐octynylfulleride anion and oligomeric cationic species of VEs with pendant acetoxyl or malonic ester functions afforded the precursor C₆₀ end‐capped oligomers. The living VE oligomers were prepared by living cationic polymerization of diethyl 2‐(vinyloxy)ethylmalonate (VOEM) and 2‐acetoxyethyl vinyl ether (AcOVE) by the CH₃CH(OR)Cl/ZnI₂ [R = CH₂CH₂OCOCH₃ and CH₂CH₂CH(COOEt)₂, respectively] initiating system. The precursors were obtained as dark brown gummy solid in 33 and 72% yield for AcOVE and VOEM, respectively. UV‐vis and ¹³C NMR spectroscopy indicated the formation of 1,2‐disubstituted dihydrofullerene derivatives. Hydrolysis of the precursors proceeded quantitatively to give the water‐soluble C₆₀ end‐capped oligomers having oligo(sodium 2‐vinyloxyethylmalonate) [oligo(VOEMNa)] and oligo(2‐hydroxyethyl vinyl ether) [oligo(HOVE)] moieties. Solubility measurements revealed the water‐soluble C₆₀ end‐capped oligomer with oligo(VOEMNa) chain to have the excellent aqueous solubility compared to that of the water‐soluble C₆₀ derivatives thus far known; the maximum solubility in water is 96.6 mg/mL, which corresponds to 25.9 mg/mL of the C₆₀ moiety. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3578–3585, 2000     

Multifunctional coupling agents for living cationic polymerization. I. Sodiomalonate anions for vinyl ethers

A series of multifunctional malonate anions, [Na^⊕?C(COOEt)₂CH₂]_mC₆H_6?m(I; m = 2–4), were examined as polymer coupling agents for the living cationic polymerization of vinyl ethers initiated with the hydrogen iodide/zinc iodide (HI/ZnI₂) initiating system. The bifunctional anion ( 2 ;I, m = 2), 1,4-[Na^⊕?C(COOEt)₂CH₂]₂C₆H₄, terminated living polymers of isobutyl vinyl ether (IBVE) (DP _n = 10) almost quantitatively in toluene at ?15°C to give coupled living polymers with doubled molecular weights in 96% yield; the dianion 2 was dissolved in tetrahydrofuran containing 18-crown-6 for maintaining the solution homogeneous. The yield of the coupled polymers was increased with shorter living chains or in less polar solvents. Also by coupling via 2 , ABA block copolymers were obtained from living AB block polymers of IBVE and an ester-functionalized vinyl ether (CH₂?CHOCH₂CH₂OCOCH₃). Coupling of living poly(IBVE) with the trifunctional anion ( 3 ; I, m = 3) led to tri-armed polymers in 56% yield, whereas with the tetrafunctional version ( 4 ; I, m = 4), only three out of the four anions reacted to give another tri-armed polymer in 85% yield. © 1993 John Wiley & Sons, Inc.     

Selective vinyl cationic polymerization of monomers with two cationically polymerizable groups. IV. New initiating systems for selective and living polymerization of p-isopropenylphenyl glycidyl ether

A variety of cationic initiators were employed for p-isopropenylphenyl glycidyl ether (IPGE), an α-methylstyrene derivative with an epoxy pendant, and optimum initiators and reaction conditions were evaluated in terms of its selective vinyl polymerization and living polymerization. Despite the coexistence of two cationically polymerizable groups in IPGE, binary initiating systems (HI, CF₃COOH, or CH₃CH(OiBu)-OCOCH₃, each coupled with ZnI₂) and sulfonic acids (CF₃SO₃H and CH₃SO₃H) selectively polymerized the vinyl group of IPGE in CH₂Cl₂ at ?78°C to produce soluble polymers with epoxy pendant groups in high yield. Metal halides (BF₃OEt₂ and AlEtCl₂) polymerized both the vinyl and epoxy groups of IPGE to give crosslinked insoluble polymers. In contrast, under these conditions, the HI/ZnI₂ system also led to a long-lived polymer, the molecular weight of which increased upon addition of a fresh feed of monomer to a completely polymerized reaction mixture, whereas the use of other initiators resulted in nonliving polymers. At higher temperatures (?40 and ?15°C), soluble poly(IPGE) was also obtained with HI/ZnI₂, but the polymer yield decreased with raising temperature, because of the occurrence of termination reaction.     

Synthesis of poly(vinyl ether) polyols with pendant oxyethylene chains and properties of hydrophilic,thermo‐responsive polyurethanes prepared therefrom

Hydroxy‐terminated telechelic poly(vinyl ether)s with pendant oxyethylene chains were synthesized by the reaction of the CH₃CH(OCOCH₃)? O[CH₂]₄O? CH(OCOCH₃)CH₃/Et_1.5AlCl_1.5/THF‐based bifunctional living cationic polymers of 2‐methoxyethyl vinyl ether (MOVE), 2‐ethoxyethyl vinyl ether (EOVE), and 2‐(2‐methoxyethoxy)ethyl vinyl ether (MOEOVE) with water and the subsequent reduction of the aldehyde polymer terminals with NaBH₄. The obtained poly(vinyl ether) polyols were reacted with an equimolar amount of toluene diisocyanates [a mixture of 2,4‐ (80%) and 2,6‐ (20%) isomers] to give water‐soluble polyurethanes. The aqueous solutions of these polyurethanes caused thermally induced precipitation at a particular temperature depending on the sort of the thermosensitive poly(vinyl ether) segments containing oxyethylene side chains. These polyurethanes also function as polymeric surfactants, lowered the surface tension of their aqueous solutions. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1641–1648, 2010     

Design and initiators of living cationic polymerization of vinyl monomers

This paper discusses recent developments in living cationic polymerization of vinyl monomers, specifically focusing on (a) new initiating systems, (b) kinetics and mechanism, and (c) controlled polymer synthesis. The new initiating systems were based on nucleophilic stabilization of the growing carbocations, either by counteranions (as in phosphate/ZnI₂ and Me₃SiI/ZnI₂ systems) or by added Lewis bases (as 2,6-dimethylpyridine for EtAlCl₂). The kinetic study included the determination of the lifetime of living cationic polymers. The controlled polymer synthesis by living cationic processes led to not only end- and pendant-functionalized polymers of narrow molecular weight distributions but also star-shaped polymers and sequence-regulated vinyl ether oligomers with functional groups.     

Synthesis of new,functionalized poly(butyl vinyl ether) oligomers and novel copolymers containing these materials

This paper reports the synthesis and characterization of new, functionalized poly(alkyl vinyl ether) oligomers, and block copolymers containing poly(alkyl vinyl ether) and poly(methyl methacrylate). Using the HI/ZnI₂ initiating system in nonpolar solvents (hexane, toluene) at −20°C, both monofunctional and difunctional poly(alkyl vinyl ether) oligomers of predicted molecular weights precisely terminated with aldehyde, primary hydroxyl and ester endgroups have been prepared. Novel diblock copolymers comprised of poly(methyl methacrylate) and poly(butyl vinyl ether) have also been synthesized using a combination of living cationic and living group transfer polymerization.     

Gel formation in cationic polymerization of divinyl ethers. II. 2,2-Bis{4-[(2-vinyloxy)ethoxy]phenyl}propane

Cationic polymerization of 2,2-bis{4-[(2-vinyloxy)ethoxy]phenyl}propane [CH₂CH O CH₂CH₂O C₆H₄ C(CH₃)₂ C₆H₄ OCH₂CH₂ O CHCH₂; 2], a divinyl ether with oxyethylene units adjacent to the polymerizable vinyl ether groups and a bulky central spacer, was investigated in CH₂Cl₂ at 0°C with the diphenyl phosphate [(C₆H₅O)₂P(O)OH]/zinc chloride (ZnCl₂) initiating system. The polymerization proceeded quantitatively and gave soluble polymers up to 85% monomer conversion. In the same fashion as the polymerization of 1,4-bis[2-vinyloxy(ethoxy)]benzene (CH₂CH O CH₂CH₂O C₆H₄ OCH₂CH₂ O CHCH₂; 1) that we already studied, the content of the unreacted pendant vinyl ether groups of the produced soluble polymers decreased with monomer conversion, and almost all the pendant vinyl ether groups were consumed in the soluble products prior to gelation. Alternatively, endo-type double bonds were gradually formed in the polymer main chains by chain transfer reactions and other side reactions as the polymerization proceeded. The polymerization behavior of isobutyl vinyl ether (3), a monofunctional vinyl ether, under the same conditions, showed that the endo-type olefins in the polymer backbones are of no polymerization ability with the growing active species involved in the present polymerization systems. These results indicate that the intermolecular crosslinking reactions occurred primarily by the pendant vinyl ether groups, and the final stage of crosslinking process leading to gelation also may occur by the small amount of the residual pendant vinyl ether groups (supposedly less than 2%). The formation of the soluble polymers that almost lack the unreacted pendant vinyl ether groups is most likely due to the frequent occurrence of intramolecular crosslinking reactions. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1931–1941, 1999     

Living cationic polymerization of 2‐adamantyl vinyl ether

Living cationic polymerization of 2‐adamantyl vinyl ether (2‐vinyloxytricyclo[3.3.1.1]^3,7decane; 2‐AdVE) was achieved with the CH₃CH(OiBu)OCOCH₃/ethylaluminum sesquichloride/ethyl acetate [CH₃CH(OiBu)OCOCH₃/Et_1.5AlCl_1.5/CH₃COOEt] initiating system in toluene at 0 °C. The number‐average molecular weights (M_n's) of the obtained poly(2‐AdVE)s increased in direct proportion to monomer conversion and produced the polymers with narrow molecular weight distributions (MWDs) (M_w/M_n = ～1.1). When a second monomer feed was added to the almost polymerized reaction mixture, the added monomer was completely consumed and the M_n's of the polymers showed a direct increase against conversion of the added monomer. Block and statistical copolymerization of 2‐AdVE with n‐butyl vinyl ether (CH₂?CH? O? CH₂ CH₂CH₂CH₃; NBVE) were possible via living process based on the same initiating system to give the corresponding copolymers with narrow MWDs. Grass transition temperature (T_g) and thermal decomposition temperature (T_d) of the poly(2‐AdVE) (e.g., M_n = 22,000, M_w/M_n = 1.17) were 178 and 323 °C, respectively. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1629–1637, 2008     

Synthesis and reactivity of metal-containing monomers

Optically active mixed alkoxy orthotitanates with general formula Ti(OR¹)₂(OR²)(OR³) (R¹=Et, Buⁿ; R²=CH₂CH₂OCOC(Me)=CH₂; R³=menthyl, CH(Me)CH₂Me, CH(Ph)CH(NHMe)Me, CH(C₉H₆N)(C₉H₁₄N)) were obtained for the first time by transesterification. The Ti^IV monomers synthesized were characterized by elemental analysis, ozonolysis, and¹H and¹³C NMR and IR spectroscopy. Polymer products with optical activity were obtained by liquid phase radical copolymerization of Ti^IV-containing monomers. For Part 51, see Ref. 1. Deceased. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1739–1743, September, 1999.     

Amphiphilic block copolymers of vinyl ethers by living cationic polymerization. II. Synthesis and surface activity of macromolecular amphiphiles with pendant amino groups

Amphiphilic block polymers of vinyl ethers (VEs). $\rlap{--} [{\rm CH}_{\rm 2} {\rm CH}\left( {{\rm OCH}_{\rm 2} {\rm CH}_{\rm 2} {\rm NH}_{\rm 2} } \right)\rlap{--} ]_m \rlap{--} [{\rm CH}_{\rm 2} {\rm CH}\left( {{\rm OR}} \right)\rlap{--} ]_n \left( {{\rm R: }n{\rm - C}_{{\rm 16}} {\rm H}_{{\rm 33}} ,{\rm }n{\rm - C}_{\rm 4} {\rm H}_{\rm 9} ;m \simeq 40,{\rm n} = 1 - 10} \right)$ were prepared, each of which consists of a hydrophilic segment with pendant primary amino groups and a hydrophobic poly(alkyl VE) segment. Their precursors were obtained by the HI/I₂-initiated sequential living cationic polymerization of an alkyl VE and a VE with a phthalimide pendant (CH₂ = CHOCH₂CH₂Im; Im; phthalimide group), where the segment molecular weights and compositions (m/n ratio) could be controlled by regulating the feed ratio of two monomers and the concentration of hydrogen iodide. Hydrazinolysis of the imide functions gave the target polymers which were readily soluble in water under neutral conditions at room temperature. These amphiphilic block polymers lowered the surface tension of their aqueous solutions (0.1 wt%, 25°C) to a minimum ? 30 dyn/cm when the hydrophobic pendant R was n-C₄H₉ (n = 4–9). The polymers with n-C₄H₉ pendants in the hydrophobic segment exhibited a higher surface activity than those with n-C₁₆ H₃₃ pendants. The surface activity of the polymers also depended on the pH of the polymer solutions; the surface activity increased in more basic solutions where the ionization of the amino group (? NH₂)2? NH₃^⊕) is suppressed.     

Preparation and properties of poly(alkyl vinyl ether-2-ethyl-2-oxazoline) diblock copolymers

A method for the synthesis of well-defined poly(alkyl vinyl ether–2-ethyl-2-oxazoline) diblock copolymers with hydrolytically stable block linkages has been developed. Monofunctional poly(alkyl vinyl ether) oligomers with nearly Poisson molecular weight distributions were prepared via a living cationic polymerization method using chloroethyl vinyl ether together with HI/ZnI₂ as the initiating system and lithium borohydride as the termination reagent. Using the resultant chloroethyl ether functional oligomers in combination with sodium iodide as macroinitiators, 2-ethyl-2-oxazoline was polymerized in chlorobenzene/NMP to afford diblock copolymers. A series of poly(methyl vinyl ether–2-ethyl-2-oxazoline) diblock materials were found to have polydispersities of ≈ 1.3–1.4 and are microphase separated as indicated by two T_g's in their DSC thermograms. These copolymers are presently being used as model materials to study fundamental parameters important for steric stabilization of dispersions in polar media. © 1993 John Wiley & Sons, Inc.     

Living cationic polymerization of an azide‐containing vinyl ether toward addressable functionalization of polymers

We first achieved the living cationic polymerization of azide‐containing monomer, 2‐azidoethyl vinyl ether (AzVE), with SnCl₄ as a catalyst (activator) in conjunction with the HCl adduct of a vinyl ether [H‐CH₂CH(OR)‐Cl; R ? CH₂CH₂Cl, CH₂CH(CH₃)₂]. Despite the potentially poisoning azide group, the produced polymers possessed controlled molecular weights and fairly narrow distributions (M_w/M_n ～ 1.2) and gave block polymers with 2‐chloroethyl vinyl ether. The pendent azide groups are easily converted into various functional groups via mild and selective reactions, such as the Staudinger reduction and copper‐catalyzed azide‐alkyne 1,3‐cycloaddition (CuAAC; a “click” reaction). These reactions led to quantitative pendent functionalization into primary amine (? NH₂), hydroxy (? OH), and carboxyl (? COOH) groups, at room temperature and without any acidic or basic treatment. Thus, poly(AzVE) is a versatile precursor for a wide variety of functional vinyl ether polymers with well‐defined structures and molecular weights. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1449–1455, 2010     

Living cationic polymerization of vinyl ether with a cyclic acetal group

The living cationic polymerization of 5‐ethyl‐2‐methyl‐5‐(vinyloxymethyl)‐1,3‐dioxane ( 1 ), a vinyl ether with a cyclic acetal unit, was investigated with various initiating systems in toluene or methylene chloride at 0 to ?30 °C. With initiating systems such as hydrogen chloride (HCl)/zinc chloride (ZnCl₂), isobutyl vinyl ether–acetic acid adduct [CH₃CH(OiBu)OCOCH₃]/tin tetrabromide (SnBr₄)/di‐tert‐butylpyridine (DTBP), and CH₃CH(OiBu)OCOCH₃/ethylaluminum sesquichloride (Et_1.5AlCl_1.5)/ethyl acetate (CH₃COOEt), the number‐average molecular weights (M_n's) of the obtained poly( 1 )s increased in direct proportion to the monomer conversion and produced polymers with relatively narrow molecular weight distributions [MWDs; weight‐average molecular weight/number‐average molecular weight (M_w/M_n) = 1.2–1.3]. To investigate the living nature of the polymerization with CH₃CH(OiBu)OCOCH₃/SnBr₄/DTBP, a second monomer feed was added to the almost polymerized reaction mixture. The added monomer was completely consumed, and the M_n values of the polymers showed a direct increase against the conversion of the added monomer, indicating the formation of a long‐lived propagating species. The glass transition temperature and thermal decomposition temperature of poly( 1 ) (e.g., M_n = 13,600, M_w/M_n = 1.30) were 29 and 308 °C, respectively. The cyclic acetal group in the pendants of the polymer of 1 could be converted to the corresponding two hydroxy groups in a 65% yield by an acid‐catalyzed hydrolysis reaction. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4855–4866, 2007     

Features of thermal decomposition of acrylates and methacrylates based on tert-butylperoxy-α-chloroalkoxyethanes

The kinetics of thermal decomposition of acrylic and methacrylic peroxides of general formula (CH₃)₃COOCH₂CH₂OCH(R¹)OC(O(R², where R¹ = H, Me, Et and R² = CH=CH₂, (CH₃)c=CH₂, Et, in the absence of solvent was studied.     

1‐Silacyclopent‐2‐enes and 1‐silacyclohex‐2‐enes bearing functionally substituted silyl groups in 2‐positions. Novel electron‐deficient Si?H?B bridges

The reactions of alkyn‐1‐yl(vinyl)silanes R₂Si[C?C‐Si(H)Me₂]CH?CH₂ [R = Me (1a), Ph (1b)], Me₂Si[C?C‐Si(Br)Me₂]CH?CH₂ (2a), and of alkyn‐1‐yl(allyl)silanes R₂Si[C?C‐Si(H)Me₂]CH₂CH?CH₂ (R = Me (3a), R = Ph (3b)] with 9‐borabicyclo[3.3.1]nonane in a 1:1 ratio afford in high yield the 1‐silacyclopent‐2‐ene derivatives 4a, b and 5a, and the 1‐silacyclohex‐2‐ene derivatives 6a, b, respectively, all of which bear a functionally substituted silyl group in 2‐position and the boryl group in 3‐position. This is the result of selective intermolecular 1,2‐hydroboration of the vinyl or allyl group, followed by intramolecular 1,1‐organoboration of the alkynyl group. In the cases of 4a, b, potential electron‐deficient Si? H? B bridges are absent or extremely weak, whereas in 6a,b the existence of Si? H? B bridges is evident from the NMR spectroscopic data (¹H, ¹¹B, ¹³C and ²⁹Si NMR). The molecular structure of 4b was determined by X‐ray analysis. Copyright © 2005 John Wiley & Sons, Ltd.     

Neutral counterparts of the C2H7O+ isomers

The neutral counterparts of the C₂H₇O⁺ isomers CH₃O⁺ (H)CH₃, CH₃CH₂OH₂⁺ and $ {\rm C}_2 \,{\rm H}_4 \,\, \cdot \cdot \cdot \mathop {\rm H}\limits^ + \, \cdot \cdot \cdot {\rm OH}_2 $ were studied by neutralization-reionization mass spectrometry. Protonated dimethyl ether and its —O(D)⁺ analogue were produced by protonation (deuteration) of dimethyl ether and also generated as a fragment ion from (labeled) ionized CH₃OCH₂CH(OH)CH₃ by loss of CH₃CO?. It was observed that the dissociation characteristics of the ions and the stability of their neutral counterpart depended on the internal energy of the protonated ether ions. Stable neutral CH₃?(H)CH₃ was only produced from energy-rich ions. The classical protonated ethanol ion CH₃CH₂OH₂⁺ (a) was produced at threshold by the loss of CH₃CO?. from ionized butane-2,3-diol. Mixtures of a with the non-classical ion $ {\rm C}_2 \,{\rm H}_4 \,\, \cdot \cdot \cdot \mathop {\rm H}\limits^ + \, \cdot \cdot \cdot {\rm OH}_2 $ (b) were produced by reaction of C₂H₅⁺ ions with H₂O. As for the protonated ether, only high-energy a and/or b ions yielded stable hypervalent radicals. It is suggested that the stable C₂H₇?O radicals are Rydberg states.     

Synthesis of polyacetals with various main‐chain structures by the self‐polyaddition of vinyl ethers with a hydroxyl function

To establish the optimum conditions for obtaining high molecular weight polyacetals by the self‐polyaddition of vinyl ethers with a hydroxyl group, we performed the polymerization of 4‐hydroxybutyl vinyl ether (CH₂?CH? O? CH₂CH₂CH₂CH₂? OH) with various acidic catalysts [p‐toluene sulfonic acid monohydrate, p‐toluene sulfonic anhydride (TSAA), pyridinium p‐toluene sulfonate, HCl, and BF₃OEt₂] in different solvents (tetrahydrofuran and toluene) at 0 °C. All the polymerizations proceeded exclusively via the polyaddition mechanism to give polyacetals of the structure [? CH(CH₃)? O? CH₂CH₂CH₂CH₂? O? ]_n quantitatively. The reaction with TSAA in tetrahydrofuran led to the highest molecular weight polymers (number‐average molecular weight = 110,000, weight‐average molecular weight/number‐average molecular weight = 1.59). 2‐Hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, cyclohexane dimethanol monovinyl ether, and tricyclodecane dimethanol monovinyl ether were also employed as monomers, and polyacetals with various main‐chain structures were obtained. This structural variety of the main chain changed the glass‐transition temperature of the polyacetals from approximately ?70 °C to room temperature. These polyacetals were thermally stable but exhibited smooth degradation with a treatment of aqueous acid to give the corresponding diol compounds in quantitative yields. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4053–4064, 2002     

Synthesis,kinetic study,and application of Ti[O(CH2)4OCHCH2]4 in ring‐opening polymerization of ε‐caprolactone and radical polymerization

Ti[O(CH₂)₄OCH?CH₂]₄, used for the ring‐opening polymerization (ROP) of ε‐caprolactone, was synthesized through the ester‐exchange reaction of titanium n‐propoxide and 1,4‐butanediol vinyl ether, and its chemical structure was confirmed by nuclear magnetic resonance (¹H NMR) and thermogravimetric analysis (TGA). The mechanism and kinetics of Ti[O(CH₂)₄OCH?CH₂]₄‐initiated bulk polymerization of ε‐caprolactone were investigated. The results demonstrate that Ti[O (CH₂)₄OCH?CH₂]₄‐initiated polymerization of ε‐caprolactone proceeds through the coordination‐insertion mechanism, and all the four alkoxide arms in Ti[O (CH₂)₄OCH?CH₂]₄ share a similar activity in initiating ROP of ε‐caprolactone. The polymerization process can be well predicted by the obtained kinetic parameters, and the activation energy is 106 KJ/mol. Then, the rheological method was employed to investigate the feasibility of producing the crosslinked poly(ε‐caprolactone)‐poly (n‐butyl acrylate) network by using Ti[O(CH₂)₄OCH?CH₂]₄ as the ROP initiator. The tensile test demonstrates that the in situ generated crosslinked PCL‐PBA network in PMMA matrix provides the possibility of ameliorating the tensile properties of PMMA. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7773–7784, 2008     

Selective vinyl cationic polymerization of monomers with two cationically polymerizable groups. III. 2-vinyloxyethyl glycidyl ether: An epoxy-functionalized vinyl ether

Cationic polymerization of 2-vinyloxyethyl glycidyl ether (VEGE), a vinyl ether with an epoxy group, was conducted with various initiators in CH₂Cl₂ in the temperature range from +15 to ?78°C, and the possibility of its selective vinyl polymerization was investigated. BF₃OEt₂ polymerized both vinyl and epoxy groups of VEGE to yield polymers partially insoluble in organic solvents. HI/I₂, iodine, and CF₃SO₃H gave soluble, low-molecular-weight oligomers with epoxy pendants. ¹H-NMR structural analysis of the oligomeric products showed that the epoxy/vinyl ratio of the pendants decreases in the order: 100% epoxy ～ CF₃SO₃H > HI/I₂ ～ I₂ ? BF₃OEt₂. Although HI/I₂ or iodine mainly polymerized the vinyl group, the reaction of the vinyl ether-type growing end with an epoxy group of VEGE took place during the polymerization, so that the monomer conversion leveled off at about 40%.