Enzymatic synthesis of a soluble polyphenol derivative from 4,4′-biphenyldiol

Enzymatic oxidative polymerization of 4,4′-biphenyldiol was performed in an aqueous organic solvent using horseradish peroxidase as catalyst. In the polymerization using a mixture of 1,4-dioxane and phosphate buffer (pH 7.0) (80:20 vol-%) as solvent, the monomer was quantitatively consumed to give powdery polymeric materials in a high yield. The resulting polymer is soluble in polar solvents such as N,N-dimethylformamide, dimethyl sulfoxide, and acetone. The molecular weight of the methylated product is 7.3 × 10³. The polymer exhibits high thermal stability under nitrogen.     

Oxidative polymerization of phenylenediamines catalyzed by horseradish peroxidase

Ortho-, meta-, and para-phenylenediamines were polymerized using hydrogen peroxide as an oxidant and horseradish peroxidase as a catalyst in mixed solvents of 1,4-dioxane and water. The yield of the polymers was strongly dependent on solvent composition, and maximum yields were obtained at 15–30% 1,4-dioxane. The analysis of circular dichroic spectra of the enzyme suggested that enzyme structure was significantly modified at high 1,4-dioxane contents, which may be responsible for the decrease of catalytic activity of the enzyme. On the basis of IR and electronic spectra of the polymers, it was considered that o- and p-phenylenediamine polymers retain disubstituted benzene nuclei, which suggests that the polymerization proceeded mainly via N—N coupling. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2593–2600, 1998     

Living cationic polymerization of vinyl ethers with carboxylic acid/tin tetrahalide initiating systems. I. New initiating systems based on acetic acid and selection of Lewis acid and basic additive leading to living polymers with low polydispersity

Cationic polymerization of isobutyl vinyl ether (IBVE) with acetic acid (CH₃COOH)/tin tetrahalide (SnX₄: X = Cl, Br, I) initiating systems in toluene solvent at 0°C was investigated, and the reaction conditions for living polymerization of IBVE with the new initiating systems were established. Among these tin tetrahalides, SnBr₄ was found to be the most suitable Lewis acid to obtain living poly(IBVE) with a narrow molecular weight distribution (MWD). The polymerization with the CH₃COOH/SnBr₄ system, however, was accompanied with the formation of a small amount of another polymer fraction of very broad MWD, probably due to the occurrence of an uncontrolled initiation by SnBr₄ coupled with protonic impurity. Addition of 1,4-dioxane (1–1.25 vol %) or 2,6-di-tert-butylpyridine (0.1–0.6mM) to the polymerization mixture completely eliminated the uncontrolled polymer to give only the living polymer with very narrow MWD (M _w/M _n ≤ 1.1; M _w, weight-average molecular weight; M _n, number-average molecular weight). The M _n of the polymers increased in direct proportion to monomer conversion, continued to increase upon sequential addition of a fresh monomer feed, and was in good agreement with the calculated values assuming that one CH₃COOH molecule formed one polymer chain. Along with these results, kinetic study and direct ¹H-NMR observation of the living polymerization indicated that CH₃COOH and SnBr₄ act as so-called “initiator” and “activator”, respectively, and the living polymerization proceeds via an activation of the acetate dormant species. The basic additives such as 1,4-dioxane and 2,6-di-tert-butylpyridine would serve mainly as a “suppressor” of the uncontrolled initiation by SnBr₄. The polymers produced after quenching the living polymerization with methanol possessed the acetate dormant terminal and they induced living polymerization of IBVE in conjunction with SnBr₄ in the presence of 1,4-dioxane. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 3173–3185, 1998     

Lipase-catalyzed polycondensation of dicarboxylic acid–divinyl esters and glycols to aliphatic polyesters

Lipase-catalyzed polymerization of dicarboxylic acid–divinyl esters with glycols has been performed. The vinyl esters used were divinyl adipate and divinyl sebacate. Lipases derived from Candida antarctica, Mucor miehei, Pseudomonas cepacia, and P. fluorescens showed high catalytic activity toward the present polymerization. Effects of solvent, reaction temperature, and enzyme amount were systematically investigated. A combination of divinyl adipate, 1,4-butanediol, and P. cepacia lipase afforded the highest molecular weight (2.1 × 10⁴). The yield of the polymer from divinyl sebacate was higher than that from divinyl adipate, whereas the opposite tendency was observed in the polymer molecular weight. Methylene chain length of α,ω-alkylene glycol also affected the polymerization behavior. The enzymatic polymerization of divinyl sebacate with cis-2-butene-1,4-diol and 2-butyne-1,4-diol resulted in the polymer containing unsaturated group in the polymer backbone. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2737–2745, 1999     

Poly[(sodium sulfamate/carboxylate)isoprene‐b‐2‐vinyl pyridine] block polyampholytes: Synthesis and self‐assembly in aqueous media

We report on the synthesis of poly[(sodium sulfamate/carboxylate) isoprene‐b‐2‐vinyl pyridine] block polyampholytes (SCPI‐P2VP), utilizing anionic polymerization and post polymerization functionalization reactions. The precursor poly(isoprene‐b‐(2‐vinylpyridine)) diblock copolymers (PI‐P2VP), containing a polyisoprene (PI) block with high 1,4 microstructure, were prepared by anionic polymerization high vacuum techniques, in two steps, involving change of the polymerization solvent. Subsequent functionalization of the PI block with chlorosulfonyl isocyanate, introduced sulfamate and carboxylate groups in the polymer chains and produced the desired block polyampholytes. The successful synthesis of the polyampolytes was corroborated by elemental analysis and IR spectroscopy measurements. The self‐assembly behaviour of the aforementioned polyampholytes was studied in aqueous solutions as a function of pH, by aid of dynamic and static light scattering, zeta potential, fluorescence spectroscopy and atomic force microscopy. Experimental results indicate that the block polyampholytes form micellar structures with P2VP cores and SCPI coronas at pH > 6, whereas more compact nanoparticles are formed at pH < 4 from the complexation of positively charged P2VP and SCPI, stabilized by excess negative charges of uncomplexed SCI segments. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Manganese(III) acetate‐catalyzed synthesis of polyguaiacol

Polyguaiacol was synthesized in the mixtures of water and various organic solvents using manganese(III) acetate as a new catalyst for radical polymerization and a biomimetic model for manganese peroxidase. Aqueous solutions of 30–70% (v/v) acetonitrile, 1,4‐dioxane, and methanol were used as model solvent mixtures. The polymer yield in the methanol (<30%) solution was lower than that in the acetonitrile or 1,4‐dioxane solution (60–90%). The average molecular weight of the polymer was also lowest in the methanol solution. Difference UV absorption spectroscopy analysis revealed that nonhydrated guaiacol clusters were found to be dominant in acetonitrile and 1,4‐dioxane solutions, especially when the content of 1,4‐dioxane was 50% (v/v) or higher. In the methanol solution, only the hydrated guaiacol clusters were observed. From the comparison of ¹H NMR data for polyguaiacol and products of guaiacol oxidation by manganese(III) acetate, 3‐(4‐hydroxy‐3‐methoxy‐phenyl)‐5,3′‐dimethoxy‐4,4′‐biphenol and a mixture of 5‐(4‐hydroxy‐3‐methoxyphenyl)‐3,3′‐dimethoxy‐4,4′‐biphenoquinone and 3‐(4‐hydroxy‐3‐methoxyphenyl)‐5,3′‐dimethoxy‐4,4′‐biphenoquinone were found to be the major structural units of polyguaiacol. Water molecule is not involved in the formation of these compounds. Therefore, the polymerization should take place readily not in methanol but in acetonitrile and 1,4‐dioxane solutions. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6009–6015, 2008     

Synthesis of polycarbonates by a silicon-assisted alkoxy/carbonylimidazolide coupling reaction

The investigation of a silicon-mediated coupling reaction between hydroxyl and carbonylimidazolide functional groups in the preparation of carbonate linkages is described. Application of this reaction to the formation of aliphatic polycarbonates was accomplished by the polymerization of an AB monomer unit, which was composed of 1,4-cyclohexanediol, where one of the hydroxyl groups was protected as a dimethylphenylsilyl ether and the other carried the carbonylimidazolide functionality. Reaction of this monomer with cesium fluoride removed the silicon protecting group and the resulting alkoxy anion promoted polymerization. Poly(1,4-cyclohexanecarbonate)s with typical molecular weights of M_w = 20,000 and M_n = 7300 a.m.u. (from GPC based upon polystyrene standards) were prepared in ca. 65% yield. The polymer showed a glass transition temperature at 138°C by DSC. TGA gave 85% mass loss between 275 and 350°C. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1133–1137, 1997.     

Synthesis and nonlinear properties of poly[1,4‐bis(4‐alkylpyridinium)butadiyne triflate]

1,4‐Bis(4‐alkylpyridinium)butadiyne triflate ( 2a and 2b ) that was prepared by the reaction of 1,4‐bis(4‐pyridyl)butadiyne ( 1 ) with alkyl trifluoro‐methanesulfonate, was found to grow into a large crystal as a result of the quaternized structure. The thermal treatment of 2a and 2b gave rise to 1,4‐addition polymerization to yield the polydiacetylene. The third‐order nonlinear optical susceptibility [χ⁽³⁾] of the polymer was determined by the femto‐second Z‐scan method to exhibit the remarkable high value of 1.1 × 10^?11 esu at 650 nm. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3686–3691, 2001     

Synthesis and solution properties of poly(vinyl ether)s with long alkyl chain,biphenyl, and cholesteryl pendants

The judicious choice of reaction conditions permitted living cationic polymerization of vinyl ethers with bulky and strongly interacting pendant groups, such as crystalline long alkyl chains and liquid crystalline mesogenic structures, using appropriate combinations of Lewis acids with added bases. Thus, well‐defined random and block copolymers with various pendants were also synthesized. Highly sensitive UCST‐type phase separation in various organic solvents was achieved employing crystallization of octadecyl pendants of homopolymers and random copolymers. This phase separation behavior is unusual for a polymer‐organic solvent system. Furthermore, thermally induced reversible physical gelation was conducted using this thermosensitive behavior. These specific pendants were very effective not only in organic media but also in water, in obtaining hydrogels with relatively low polymer concentrations. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4392–4406, 2008     

Solid-state polymerization of hexaphenylcyclotrisiloxane

The anionic solid-state polymerization of triclinic crystals of hexaphenylcyclotrisiloxane (HPhTS) initiated by KOH and potassium oligo(methylphenylsiloxane) has been studied. It was found that this reaction can yield high molecular weight poly(diphenylsiloxane) (PDPhS) with a specific viscosity up to 5 (1 wt % diphenyloxide solution at 145°C). The main features of the process are as follows: (a) this is a heterogeneous reaction that proceeds inward from the surface of HPhTS crystals; (b) the crystalline polymer is obtained from the crystalline trimer; (c) OPhTS simultaneously forms along with the polymer; (d) the specific viscosity of the resulting polymer remains constant or decreases with polymerization time and, consequently, with the conversion of HPhTS; and (e) the crystallinity of polymerized PDPhS samples depends inversely on its specific viscosity. Together, these features suggest that polymerization and crystallization proceed successively. The morphologies of the resulting PDPhS phase revealed by means of scanning electron microscopy are consistent with this mechanism. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1973–1984, 1997     

Emulsion and miniemulsion polymerizations with an oil‐soluble initiator in the presence and absence of an aqueous‐phase radical scavenger

Butyl acrylate conventional emulsion (macroemulsion) and miniemulsion polymerizations were carried out with an oil‐soluble initiator (azobisisobutyronitrile) in the presence or absence of an aqueous‐phase radical scavenger. For macroemulsion polymerization, in the presence of an aqueous‐phase radical scavenger, no particle nucleation occurred, whereas in the absence of an aqueous‐phase radical scavenger, particle nucleation proceeded as expected. For miniemulsion polymerization, the rate of polymerization was much higher in the absence of an aqueous‐phase radical scavenger than in its presence. Furthermore, in the absence of an aqueous‐phase radical scavenger, the miniemulsion polymerization rate increased with reduced droplet size, whereas in the presence of an aqueous‐phase radical scavenger, the trend was reversed. It is concluded that (1) for macroemulsion polymerization, the contribution from free radicals originating in the aqueous‐phase is predominant in the micellar nucleation of particles; (2) free radicals originating in the particle phase contribute to the rate of polymerization and the contribution increases with an increase in the particle size; and (3) for polymer particles with diameters of up to approximately 100 nm, polymerization is initiated from free radicals originating in the aqueous phase. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3200–3211, 2002     

Chiroptical aggregates from block copolymer bearing amino acid moieties in aqueous solution

Optically active poly(ethylene glycol) monomethyl ether‐b‐poly(methacryloyl‐L ‐leucine methyl ester) (denoted as MPEG‐b‐PMALM) copolymers were prepared via atom transfer radical polymerization (ATRP), using bromine (Br) end‐capped poly(ethylene glycol) monomethyl ether (denoted as MPEG‐Br) as macroinitiator in the presence of CuBr/tris(2‐dimethylaminoethy1)amine (Me₆TREN) as catalytic system. Broad range of morphologies, such as spherical, cylindrical, and vesicular micelles, which were prepared by initially dissolving prepared polymer in organic solvent at different concentration followed by addition various amount of water before dialysis against water to remove any added solvent, was observed by transmission electron microscope (TEM). More detailed chiroptical properties of the micelles/aggregates in aqueous solution were evaluated by circular dichroism (CD) spectroscopy as a function of micelles morphologies, polymer concentration, solvents employed, temperature, etc. The micellar solutions exhibit almost the same CD spectra regardless of its morphologies. The intensity of the CD spectra of the cylindrical micelles decreased in the molar ellipticities as the micellar concentration in water was increased. The Cotton effect was markedly changed when the solvent hydrophobicity was changed by addition of trifluoromethyl ethanol (TFME) to water. The intensity of the CD spectra decreased not too much within the temperature range from 20 °C to 90 °C, indicating good stability of the micelles upon temperature variation. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1345–1355, 2009     

Synthesis and properties of an amphiphilic dithiafulvene oligomer

An amphiphilic dithiafulvene oligomer was synthesized by cycloaddition polymerization of aldothioketene generated from 1,4‐diethynylbenzene and a PEO‐grafted phenylacetylene (feed ratio 5/1). The degree of polymerization was determined as 6 by ¹H NMR analysis. The aggregation behavior of the oligomer was studied in the mixed solvent of D₂O and DMSO‐d₆. Effective charge‐transfer interaction of the oligomer and hydrophilic methyl viologen was observed in an aqueous solution. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3770–3775, 2007     

Preparation of macroporous functionalized polymer beads by a multistep polymerization and their application in zirconocene catalysts for ethylene polymerization

Macroporous functionalized polymer beads of poly(4‐vinylpyridine‐co‐1,4‐divinylbenzene) [P(VPy‐co‐DVB)] were prepared by a multistep polymerization, including a polystyrene (PS) shape template by emulsifier‐free emulsion polymerization, linear PS seeds by staged template suspension polymerization, and macroporous functionalized polymer beads of P(VPy‐co‐DVB) by multistep seeded polymerization. The polymer beads, having a cellular texture, were made of many small, spherical particles. The bead size was 10–50 μm, and the pore size was 0.1–1.5 μm. The polymer beads were used as supports for zirconocene catalysts in ethylene polymerization. They were very different from traditional polymer supports. The polymer beads could be exfoliated to yield many spherical particles dispersed in the resulting polyethylene particles during ethylene polymerization. The influence of the polymer beads on the catalytic behavior of the supported catalyst and morphology of the resulting polyethylene was investigated. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 873–880, 2003     

Anomalous solubility of polyacrylamide prepared by dispersion (precipitation) polymerization in aqueous tert‐butyl alcohol

Polyacrylamide prepared by dispersion (precipitation) polymerization in an aqueous t‐butyl alcohol (TBA) medium is only partially soluble when the TBA concentrations in the polymerization media are in the range 82 vol % < TBA < 95 vol %. Independent experiments with a soluble (linear) sample of polyacrylamide show that the polymer swells sufficiently in the aforementioned media to lower the glass‐transition temperature of the polymer below the polymerization temperature (50 °C). The anomalous solubility has been attributed to the crosslinking of polymer chains that occurs during the solid‐phase polymerization of acrylamide in the swollen polymer particles. It is postulated that some of the radical centers shift from the chain end to the chain backbone during solid‐phase polymerization by chain transfer to neighboring polymer molecules, and when pairs of such radicals come into close vicinity, crosslinking occurs. However, dispersion (precipitation) polymerization in other media such as aqueous methanol and aqueous acetone yields polymers that are soluble. This result has been attributed to the fact that the polymer radical undergoes a chain‐transfer reaction with these solvents at a much faster rate than with TBA, which overcomes the effect of the polymer‐transfer reaction. Even the addition of as little as 5% methanol to a TBA–water mixture (TBA:water = 85:10) gives rise to a soluble polymer. The chain‐transfer constants for acetone, methanol, and TBA have been determined to be 9.0 × 10^?6, 6.9 × 10^?6, and 1.48 × 10^?6, respectively, at 50 °C. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3434–3442, 2001     

Amphiphilic PEG/alkyl‐grafted comb polylactides

Amphiphilic polylactides (PLAs) with well‐defined architectures were synthesized by ring‐opening polymerization of AB monomers (glycolides) substituted with both a long chain alkyl group and a triethylene glycol segment terminated in either a methyl or benzyl group. The resulting amphiphilic PLAs had number average molecular weights >100,000 g/mol. DSC analysis revealed a first‐order phase transition at ～ 20 °C, reflecting the crystalline nature of the linear alkyl side chains. Polymeric micelles were prepared by the solvent displacement method in water. Dynamic light scattering measurements support formation of a mixture of 20‐nm‐diameter unimolecular micelles and 60‐nm particles comprised of an estimated 25 polymer molecules. UV–vis characterization of micelles formed from acetone–water solutions containing azobenzene confirmed encapsulation of the hydrophobic dye, suggesting their potential as new amphiphilic PLAs as drug delivery vehicles. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5227–5236, 2007     

Miniemulsion polymerization of styrene with a block copolymer surfactant

A series of miniemulsion systems based on styrene/azobisisobutyronitrile in the presence of poly(methyl methacrylate‐b‐2‐(dimethylamino)ethyl methacrylate) as a surfactant and hexadecane (HD) as a cosurfactant were developed. For comparison, a series of pseudoconventional emulsions also were carried out with the same procedure used for the aforementioned series but without the cosurfactant (HD). Both the droplet size and shelf life were also measured. Experimental results indicate that it is possible to slow the effect of Ostwald ripening and thereby produce a stable miniemulsion with the block copolymer as the surfactant and HD as the cosurfactant. In addition, the extent to which varying the surfactant concentration and copolymer composition could affect both the polymer particle size during the polymerization and the polymerization rate was examined. Variation in the polymer particle sizes during polymerization indicates that droplet and aqueous (micellar or both homogeneous) nucleation occurs in the miniemulsion polymerization. With the same concentration of the surfactant used in the miniemulsion polymerization, the polymerization rates of systems with M₁₂B₃₆ are faster than those of systems with M₁₂B₁₂. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1818–1827, 2000     

Polyepichlorohydrine stabilized core shell microspheres by dispersion polymerization

Polystyrene microspheres ranging in diameter from 2 to 10 μm were prepared by dispersion polymerization in the presence of polyepichlorohydrine as the steric stabilizer precursor in alcoholic media. To clarify the effects of the solvent mixture composition, initiator concentration and steric stabilizer amount on the microsphere characteristics, including the molar mass parameters of the polymeric material, the microsphere size, and the steric stabilizer surface density, a three-factor full factorial design involving two levels of each of the factors and replicate experiments was employed. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 681–688, 1997     

Synthesis of π‐conjugated poly(dithiafulvene) by cycloaddition polymerization of aldothioketene from a bis(1,2,3‐thiadiazole) monomer

A π‐conjugated poly(dithiafulvene) ( 2 ) was obtained by the cycloaddition polymerization of aldothioketene with its alkynethiol tautomer derived from 1,4‐bis(1,2,3‐thiadiazolyl‐4‐yl)benzene ( 1 ) in a 94% yield. To a mixure of 1 and dimethyl sulfoxide (DMSO)/ethanol (5/1, v/v), KOH was added. After stirring the mixture overnight, piperidine was added to quench the terminal thioketenes. The reaction mixture was then poured into water to obtain the product. The cycloaddition polymerization of aldothioketene derived from 1 with its alkynethiol tautomer was studied under various conditions in several solvent systems. The structure of the polymer was supported by the ¹H NMR and ¹³C NMR spectra. The number‐average degree of polymerization (DP) of 2 was 8, estimated from the ¹H NMR analysis. Optical properties and electrochemical analysis of 2 were also studied. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5872–5876, 2004     

Cationic polymerization behavior of seven-membered cyclic sulfite

Cationic ring-opening polymerization behavior of a seven-membered cyclic sulfite ( 1 ) was examined. 1 was prepared by the reaction of 1,4-butanediol with SOCl₂ in 58% yield. The cationic polymerization of 1 was carried out at 0, 25, 60, or 100°C with trifluoromethanesulfonic acid (TfOH), methyl trifluoromethanesulfonate (TfOMe), BF₃ · OEt₂, SnCl₄, methyl p-toluenesulfonate (TsOMe), or MeI as an initiator in bulk under a nitrogen atmosphere to afford the polymer with M̄_n 1000–10,400. The order of activities of the initiators for 1 was as follows, TfOH ≅ TfOMe > SnCl₄ > BF₃ · OEt₂ > TsOMe ≅ MeI. The polymerization of 1 with TfOMe afforded a poly(sulfite) below 25°C, but afforded a polymer containing an ether unit at 60°C, which was formed by a desulfoxylation. The higher the activity of the initiator was, the more easily the desulfoxylation occurred. We expected volume expansion on polymerization because cyclic sulfites have large dipole moment values, but it turned out that 1 showed 4.34% shrinkage on polymerization. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3673–3682, 1997