Novel lipase-catalyzed ring-opening copolymerization of oxiranes and dicarboxylic anhydride forming polyesters bearing carboxyl groups and their physicochemical properties and biodegradability

Oxiranes, such as benzyl glycidate and glycidyl phenyl ether, were copolymerized with dicarboxylic anhydride by lipase at a temperature between 60 and 80 °C to yield the corresponding polyesters bearing carboxyl or phenyl groups. Bulk polymerization, especially at 80 °C, and preferably using porcine pancreatic lipase, gave biodegradable polyesters with a molecular weight of greater than 10000. Poly(sodium carboxylate)s containing ester linkages in the backbone prepared in this study were readily biodegradable by the activated sludge and exhibited a calcium ion sequestration capacity.     

Parent homopolymers of liquid crystalline polyesters

A method that combines multi-temperature powder X-ray diffraction and molecular modelling is used to determine the high temperature crystal structures for poly-(p-phenylene terephthalate) (PPT) and poly-(p-hydroxybenzoic acid) (PHBA). Both have high temperature structures characterized by a degree of rotational disorder. In the case of PHBA there is a distinct high temperature phase above a well defined transition at 350°C, whereas the rotational disorder in ‘as polymerized’ PPT increases gradually between 370 and 475°C. The interchain packing at high temperatures still maintains phenyl edge to phenyl face correlations and, to some degree, carbonyl carbon to carbonyl oxygen contacts. The findings are relevant to the molecular structure and phase behaviour of liquid-crystalline polyesters as a class.     

Synthesis and Characterization of Soluble Polyester Based on Calixarene Dicarboxylic Acid with Tertiary Butyl Pendant Groups

A series of new polycalixesters(PCES) were synthesized by polyesterification of calixarene dicarboxylic acid derivatives having tertiary butyl pendant groups at the upper rim using five different diols. All polyesters were readily soluble in polar solvents such as NMP(N-methylpyrrolidone), DMF(dimethylformamide), DMSO(dimethylsulfoxide), pyridine, THF(tetrahydrofurane), HMPA(hexamethylenephosphoramide) and DMAC(dimethylacetamide). The PCES were also partially soluble in TCE(tetrachloroethane) and ethanol and they were unsoluble in aceton. The glass transition temperatures of polyesters were between 80-184 °C, the crystallinity temperatures of polyesters were between 130–212 °C and the melting temperatures of polyesters were between 185–234 °C, as determined by differential scanning calorimeter(DSC). The inherent viscosities of polyesters were obtained from 0.55 dL/mg to 0.61 dL/mg. The temperatures at 10% weight loss of polyesters ranged from 182 °C to 237 °C. The temperatures at 25% weight loss of polyesters ranged from 258 °C to 331 °C. The half weight loss(50%) temperatures of polyesters were among 315 °C to 371 °C and the char yields at 600 °C were determined within 13% to 22.3% in N2 atmosphere, as determined by thermo gravimetric analysis(TGA). The polyester, PES3, has the higher melting point(234 °C) and higher inherent viscosity(molecular weight) than the other polyesters.     

Influence of aryl substituents on the thermal and solubility behavior of poly(p-phenylene terephthalate) and poly(p-phenylene terephthalamide)

The substitution of poly(p-phenylene terephthalate) and poly(p-phenylene terephthalamide) with phenyl and biphenylyl substituents (4-biphenylyl and 2-biphenylyl) in the terephthalic acid unit lowers the melting temperatures and crystallization tendency and increases the solubility. The melting temperatures of the polyesters are in the range of 285–350°C. Melting of the polyamides occurs between 440–490°C. The polyamides begin to decompose in the same temperature range. In polyesters as well as in polyamides the 2-biphenylyl substituent was found to be more effective in decreasing the crystallinity, lowering the melt transition temperatures and increasing the solubility.     

Synthesis and properties of soluble,fluorescent polyesters and polyethers with substituted m‐terphenyl segments in the main chain

A new series of rigid polyesters and semiflexible polyethers were synthesized from 4,4″‐dihydroxy‐5′‐phenyl or anthracenyl‐m‐terphenyl. The polymers were characterized by viscometry, Fourier transform infrared, NMR, X‐ray, differential scanning calorimetry, thermomechanical analysis, thermogravimetric analysis, ultraviolet–visible, and luminescence spectroscopy. The polyesters were amorphous, whereas some of the polyethers showed a low degree of crystallinity. All the polymers displayed an enhanced solubility even in 1,1,2,2‐tetrachloroethane and tetrahydrofuran. The glass‐transition temperatures were 123–146 °C for the polyesters and 45–117 °C for the polyethers. The polymers were stable up to 213–340 °C and afforded anaerobic char yields of 36–62% at 800 °C. Their optical properties were investigated both in solution and in the solid state. They showed ultraviolet fluorescence, violet‐blue fluorescence, or both with emission maxima at 333–487 nm. The polymers with anthracenyl pendent groups exhibited higher fluorescence quantum yields and emission maxima redshifted compared with the corresponding polymers with phenyl pendent groups. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2381–2391, 2000     

Lipase-catalyzed ring-opening polymerization of lactide

The six-membered lactide was polymerized using the ring-opening polymerization with lipase as a catalyst at a temperature between 80 and 130°C in bulk to yield the corresponding polylactide with weight-average molecular weights of up to 126000. The most preferable conditions with respect to the molecular weight of the polylactide are the bulk polymerization using lipase PS at a temperature of 100°C. The D ,L -lactide gave higher molecular weight compared to the D ,D - and L ,L -lactide.     

Enzymatic polyesterification in organic media. Enzyme-catalyzed synthesis of linear polyesters. I. Condensation polymerization of linear hydroxyesters. II. Ring-opening polymerization of ϵ-caprolactone

With the object to synthesize polyesters by enzymatic catalysis in organic media, two directions have been investigated: (1) the condensation polymerization of linear ω-hydroxyesters and (2) the ring-opening polymerization of lactones. The commercially-available crude porcine pancreatic lipase (PPL), suspended in organic solvents, was the preferred enzyme for the reactions. In order to determine the optimal conditions for the condensation polymerization, the bifunctional methyl 6-hydroxyhexanoate was used as a model compound to study the influence of the following parameters: type of the enzymecatalyst, kind of solvent, concentration, temperature, duration, size of the reaction mixture, and stirring. Film-forming polyesters with a degree of polymerization (DP) up to about 100 were obtained from linear aliphatic hydroxyesters in n-hexane at reflux temperature (69°C). Yet concurrently with the intermolecular condensation polymerization, macrolactones were also formed by intramolecular reaction. Two aromatic hydroxyesters did not react under these conditions. For the ring-opening polymerization of lactones the reaction of ?-caprolactone with methanol as the preferred nucleophile, was studied. Polyesters with a DP of up to 35 were obtained in n-hexane at temperatures between 25 and 40°C. The degrees of polymerization of the polyesters were determined by comparative analyses of the end groups in the ¹H-NMR spectra and by determination of molecular weights either by vapor phase osmometry, gel permeation chromatography, or intrinsic viscosity. © 1993 John Wiley & Sons, Inc.     

Poly(ethylene terephthalate) reinforced by N,N′‐diphenyl biphenyl‐3,3′,4,4′‐tetracarboxydiimide moieties

Starting with 3,3′,4,4′‐biphenyltetracarboxylic dianhydride and methyl aminobenzoate, we synthesized a novel rodlike imide‐containing monomer, N,N′‐bis[p‐(methoxy carbonyl) phenyl]‐biphenyl‐3,3′,4,4′‐tetracarboxydiimide (BMBI). The polycondensation of BMBI with dimethyl terephthalate and ethylene glycol yielded a series of copoly(ester imide)s based on the BMBI‐modified poly(ethylene terephthalate) (PET) backbone. Compared with PET, these BMBI‐modified polyesters had higher glass‐transition temperatures and higher stiffness and strength. In particular, the poly(ethylene terephthalate imide) PETI‐5, which contained 5 mol % of the imide moieties, had a glass‐transition temperature of 89.9 °C (11 °C higher than the glass‐transition temperature of PET), a tensile modulus of 869.4 MPa (20.2 % higher than that of PET), and a tensile strength of 80.8 MPa (38.8 % higher than that of PET). Therefore, a significant reinforcing effect was observed in these imide‐modified polyesters, and a new approach to higher property polyesters was suggested. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 852–863, 2002; DOI 10.1002/pola.10169     

Synthesis and characterization of new soluble cardo polyesters derived from 1,1‐bis‐[4‐(4‐chlorocarboxyphenoxy)phenyl]‐4‐tert‐butylcyclohexane with various bisphenols by solution polycondensation

A new cardo diacid chloride, 1,1‐bis‐[4‐(4‐chlorocarboxyphenoxy)phenyl]‐4‐tert‐butylcyclohexane ( 4 ), was synthesized from 1,1‐bis‐[4‐(4‐carboxyphenoxy)phenyl]‐4‐tert‐butylcyclohexane in refluxing thionyl chloride. Subsequently, various new polyesters were prepared from 4 with various bisphenols by solution polycondensation in nitrobenzene using pyridine as a hydrogen chloride quencher at 150 °C. These polyesters were produced with inherent viscosities of 0.32–0.50 dL · g^?1. Most of these polyesters exhibited excellent solubility in a variety of solvents such as N,N‐dimethylformamide, tetrahydrofuran, tetrachloroethane, dimethyl sulfoxide, N,N‐dimethylacetamide, N‐methyl‐2‐pyrrolidinone, m‐cresol, o‐chlorophenol, and chloroform. These polymers showed glass‐transition temperatures (T_g's) between 144 and 197 °C. The polymer containing the adamantane group exhibited the highest T_g value. The 10% weight loss temperatures of the polyesters, measured by thermogravimetric analysis, were found to be in the range of 426–451 °C in nitrogen. These cardo polyesters exhibited higher T_g's and better solubility than bisphenol A‐based polyesters. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2951–2956, 2001     

Purification and partial characterization of a lipase from Bacillus coagulans ZJU318

An extracellular lipase was purified from the fermentation broth of Bacillus coagulans ZJU318 by CM-Sepharose chromatography, followed by Sephacryl S-200 chromatography. The lipase was purified 14.7-fold with 18% recovery and a specific activity of 141.1 U/mg. The molecular weight of the homogeneous enzyme was (32 kDa), determined by sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis. The enzyme activity was maximum at pH 9.0 and was stable over a pH range of 7.0–10.0, and the optimum temperature for the enzyme reaction was 45°C. Little activity loss (6.2%) was observed after 1 h of incubation at 40°C. However, the stability of the lipase decreased sharply at 50 and 60°C. The enzyme activity was strongly inhibited by Ag⁺ and Cu²⁺, whereas EDTA caused no inhibition. SDS, Brij 30, and Tween-80 inhibited lipase, whereas Triton X-100 did not significantly inhibit lipase activity.     

Polyesters,polyurethanes and epoxy resins derived from 2,2′-(1,4-phenylenedivinylene)bis-8-hydroxyquinaldine and 6-(4-hydroxystyryl)-3-hydroxypyridine

New polyesters and polyurethanes as well as diepoxides bearing styrylpyridine segments were prepared utilizing 2,2′-(1,4-phenylenedivinylene)bis-8-hydroxyquinaldine (PBHQ) and 6-(4-hydroxystyryl)-3-hydroxypyridine (HSHP) as starting materials. The polyesters were prepared by reacting PBHQ or HSHP with terephthaloyl dichloride in the presence of an acid acceptor utilizing the solution polycondensation method. The polyurethanes were prepared from the reactions of PBHQ and HSHP with tolylene diisocyanate and methylenebis(4-phenylisocyanate). In addition, model diesters and diurethanes were synthesized by reacting PBHQ and HSHP with benzoyl chloride and phenyl isocyanate, respectively. Model compounds and polymers were characterized by FT-IR and ¹H-NMR spectroscopy as well as by DTA and TGA. Diepoxides were also prepared from the reactions of PBHQ and HSHP with epichlorohydrin which were polymerized in the presence of 4,4′-diaminodiphenylsulfone. The polyesters were the most thermostable polymers obtained. After curing at 240°C for 20 h, they were stable in N₂ up to 345–370°C and afforded anaerobic char yields of 65–75% at 800°C. © 1993 John Wiley & Sons, Inc.     

Fluorene‐rich high performance polyesters: Synthesis and characterization of 9,9‐fluorenylidene and 2,7‐fluorenylene‐based polyesters with excellent optical property

Polyesters PEs containing high content of fluorene units in their backbones were synthesized from 9,9‐diarene‐substituted fluorene diols ( 1 ) and fluorene‐based diacid chlorides ( 2 ) by high temperature polycondensation at 185 °C in diphenyl ether. The molecular weights of the polyesters PE1‐PE5 were in a range of M_w 25,000–165,000. The polyesters displayed their high thermostability: the glass transition temperatures (T_g) by differential scanning calorimetry analysis ranged from 109 to 217 °C, while the 10% weight loss temperatures (T_d10) measured by thermogravimetric analysis were over 400 °C in nitrogen and 395 °C in air. The polyesters had good solubility in most common organic solvents such as chloroform and toluene and gave tough, transparent and flexible cast films. The transmittance of the films was over 80% in the wavelength range from 450 to 700 nm in any PEs . The PEs exhibited high refractive index values around 1.65, while they had very low degree of birefringence. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2549–2556, 2008     

Self‐curable polyester by a reaction of glycidol with maleic anhydride

The controlled reaction of equimolar quantities of maleic anhydride and glycidol in dimethoxyethane gives soluble polyesters with one hydroxyl group in each repeating unit. The reaction proceeds with stepwise ring opening of the components and gives highly viscous clear solutions in relatively short periods. In the first step, monomaleate ester formation takes place around 80 °C. The ring opening of the oxirane group is the second step, and it occurs at 120 °C. The overall reaction is the formation of soluble polyesters with moderate molecular weights (6000–18,000), without the elimination of water. The soluble polyesters can be crosslinked tightly by direct heating at 190 °C without additional vinyl monomer. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2549–2555, 2003     

Ring-expansion polycondensation of 2-stanna-1,3-dioxepane (or 1,3-dioxepene) with dicarboxylic acid chlorides

2,2-Dibutyl-2-stanna-1,3-dioxepane 1 (or 1,3-dioxepene 2) were prepared from 1,4-butane (or 1,4-butene) diol and dibutyltin dimethoxide. They were polycondensed at 80°C in n-heptane with adipoyl-, suberoyl, sabacoyl chloride and with decane-1,10-dicarbonyl chloride. In the case of suberoyl chloride and 2,2-dibutyl-2-stanna-1,3-dioxepane reaction time, temperature and stoichiometry were varied to optimize both the molecular weight and the fraction of cyclic polyesters. With a slight excess of the dicarboxylic acid chlorides, only macrocyclic polyesters were obtained in all cases. The resulting cyclic polyesters were characterized by viscosity measurements, by ¹H and ¹³C NMR and by MALDI-TOF mass spectrometry.     

Temperature dependence of the conformation of isotactic polystyrene in toluene

In order to obtain information about a possible helix–coil transition of isotactic polystyrene (i-PS) at 80°C in toluene, as has been reported in other solvents, solution properties were examined at temperatures between 10 and 110°C. Use was made of viscometry, high-resolution nuclear magnetic resonance, infrared spectroscopy, calorimetry, and light scattering. No distinct transition was found at 80°C but rather a second-order transition between 62 and 65°C. A similar transition occurred in toluene solutions of atactic polystyrene. The transition may be attributed to a sudden change in the mobility of the phenyl side-group of the polymer. From this study it is concluded that i-PS has a helical conformation in toluene, the mean helix length decreasing smoothly with increasing temperature.     

Synthesis and degradabilities of polyesters from 1,4:3,6-dianhydrohexitols and aliphatic dicarboxylic acids

Six different polyesters ( 6a–6c and 7a–7c ) were prepared by the bulk polycondensations of the respective combinations of 1,4:3,6-dianhydro-D-glucitol ( 3 ) and 1,4:3,6-dianhydro-D-mannitol ( 4 ) with succinyl dichloride ( 5a ), glutaryl dichloride ( 5b ), and adipoyl dichloride ( 5c ) at 140–180°C. Polyesters having number average molecular weights up to 2.6 ×10⁴ were obtained in high yields. Only polyester 7a based on 4 and 5a was partially crystalline, whereas all the other polyesters were amorphous. Thin films of these polyesters except that of 7a were spontancously hydrolyzed in a neutral phosphate buffer solution at 50°C, whereas they were reluctant to be hydrolyzed at 27°C. The polyesters were more or less degraded at 27°C by treatment with an activated sludge or by prolonged burial in soil. © 1995 John Wiley & Sons, Inc.     

Reversible Transformation between Amorphous and Crystalline States of Unsaturated Polyesters by Cis–Trans Isomerization

An aliphatic polyester has been prepared from ethylene oxide and maleic anhydride that undergoes reversible transformation between amorphous (T_g=18 °C) and crystalline (T_m=124 °C) states through cis–trans isomerization of the C=C bonds in the polymer backbone without any change in either the molecular weight or dispersity of the polymer. A similar transformation was also observed in chiral unsaturated polyesters formed from enantiopure terminal epoxides, such as epichlorohydrin, phenyl glycidyl ether, and (2,3‐epoxypropyl)benzene. These unsaturated polyesters with 100 % E‐configuration in the crystalline state were prepared by quantitative isomerization of their Z‐configuration analogues in the presence of a catalytic amount of diethylamine, while in the presence of benzophenone, irradiation with 365 nm UV light resulted in the transformation of about 30 % trans‐alkene to cis‐maleate form, thereby affording amorphous polyesters.     

ESR study of primary radical formation during mechanical degradation of poly(2,6-dimethyl-p-phenylene oxide) solid

Radical formation during mechanical degradation of solid poly(2,6-dimethyl-p-phenylene oxide) (PPO) was investigated by electron spin resonance (ESR). The ESR spectrum of PPO fractured at room temperature in air consisted of eight lines with a separation of about 5.5 gauss with g = 2.0043, indicating a small asymmetry. For PPO fractured in liquid nitrogen, a similar spectrum was observed at ?196°C in air or in vacuo. These spectra have been identified as belonging to a 2,6-dimethyl-substituted phenoxy radical and thus indicate the occurrence of main-chain rupture. The phenyl radical which was expected to be formed together with a 2,6-dimethyl-substituted phenoxy radical could not be detected, but at temperatures below ?46°C a small hump was observed at g = 2.034. By subtracting the spectrum observed after decay of this hump from the original one, the resulting curve was the characteristic asymmetric spectrum of a peroxy radical, which was presumably formed by the reaction between a phenyl radical and oxygen. The radical decay curve showed two stepwise-decaying regions; one located in the temperature region between about ?120°C and ?80°C where only a small number of radicals decayed, another located in the temperature region from about ?30°C to 100°C where almost all mechanically formed radicals decayed. The latter radical decay, which occurred considerably below the glass-transition temperature of PPO, was attributed to the molecular motions associated with the mechanical β^* relaxation on the basis of the activation energy and the temperature region.     

Synthesis and properties of phosphorus-containing polyesters derived from 2-(6-oxido-6H-dibenz〈c,e〉〈1,2〉oxaphosphorin-6-yl)-1,4- hydroxyethoxy phenylene

A series of phosphorous-containing aliphatic polyesters were synthesized by high-temperature solution condensation of 2-(6-oxido-6H-dibenz〈c,e〉〈1,2〉oxaphosphorin-6-yl)-1,4-hydroxyethoxy phenylene (III) with various aromatic acid chlorides in o-dichlorobenzene. All polyesters are amorphous and readily soluble in many organic solvents such as DMAc, NMP, DMSO, and o-dichlorobenzene at room temperature or upon heating. These polyesters are thermally quite stable. The glass transition temperatures of these aliphatic polyesters ranged from 126.6 to 162.2°C. The degradation temperatures (T_d onset) in nitrogen ranged from 424 to 448°C, and the char yields at 700°C are 20–32%. The activation energies of degradation ranged from 160.9 to 226.0 kJ/mol. The LOIs of these polyesters ranged from 36 to 43. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 3051–3061, 1998     

Photoinitiated polymerization of methacrylates comprising phenyl moieties

Investigation of photopolymerization kinetics of 4-(4-methacryloyloxyphenyl)-butan-2-one (1) in comparison with 2-phenoxyethyl methacrylate (2) and phenyl methacrylate (3) using a UV-LED emitting at 395 nm shows significantly faster polymerization of 1 compared to both 2 and 3 at 40°C. Vitrification affects photopolymerization kinetics of all methacrylates under investigation. Interestingly, quantitative final conversion is observed during photoinitiated polymerization of 1 and 2 whereas 3 shows limited conversion at about 80%. Furthermore, higher degree of polymerization is obtained by photoinitiated polymerization of 1 compared to 2 and 3. This shows that the 3-oxobutyl substituent at the phenyl ring of 1 significantly affects both polymerization kinetics and final conversion of the photoinitiated polymerization. Moreover, an additional higher molecular weight fraction is observed in case of polymerization of 1 at 85°C that is above the glass transition temperature of the polymer formed during photoinitiated polymerization. As a thermal polymerization at 85°C in the absence of light results in a high molecular weight polymer as well, an additional thermal process may be discussed as reason for the higher molecular weight polymer fraction in case of the photopolymer made at 85°C.