Synthesis and characterization of functional aliphatic copolyesters

Functional aliphatic copolyesters of succinic acid (SA) and citric acid (CA) were synthesized via direct copolycondensation in the presence of 1,4‐butanediol, with titanium(IV) butoxide as a catalyst. The effects of the comonomer and comonomer ratio on the polycondensation and the melting and glass‐transition temperatures were investigated. The melting temperature was very sensitive to the molar ratio of the SA–CA comonomer units. The chain extension of this poly(butylene succinate citrate) was carried out with hexamethylene diisocyanate. The intrinsic viscosity, crystallinity percentage, and rheological properties of these copolyesters were also studied. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3232–3239, 2002     

Synthesis and properties of triaryl diamine‐based hole‐transporting monomer and polymer

The synthesis and properties of hole‐transporting triaryl diamine‐based low‐molar‐mass compounds and polymer are reported. Comparative study on their thermal, optical, and photoelectrical properties is presented. All the synthesized compounds are found to form glasses with the glass transition temperatures in the range of 43–119 °C as characterized by differential scanning calorimetry. The ionization potentials of these compounds range from 5.31 to 5.40 eV as determined by electron photoemission method. Hole‐drift mobilities in the films of the synthesized compounds were estimated by the xerographic time‐of‐flight technique. They were found to reach 10^?3 cm²/Vs at electric field of 6.4 × 10⁵ V/cm. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4674–4680, 2008     

Synthesis of polyester and copolyesters having amino acid moieties in the main chain

N, N-di (2-hydroxyethyl)-3-aminopropionic acid (M3) was synthesized and used for the preparation of a series of polyesters having amino acid moieties in the main chain and carboxyl groups as the side group. Polycondensation of M3 , diols, bisphenol A, and isophthaloyl dichloride were performed in the presence of tertiary amine by solution and interfacial methods. Molecular weights of the polymers obtained by the solution method were not high, because oligomers produced at the early stage of reaction are ionized by H⁺ ions from the by-product, and become nonreactive triethylamine hydrochloride. Polymers with high M?_w (1–10 × 10⁴) were obtained in a high yield by organic/organic two-phase interfacial polycondensation using DMAc and n-heptane as solvents. The combined nucleophilic and basic complex catalytic action of N, N, N′, N′-tetramethyl ethyiene diamine (TEMED) is suggested for the present organic phase/organic phase interfacial polycondensation. This method can be applied for the preparation of novel functional polyesters. © 1994 John Wiley & Sons, Inc.     

Biodegradable aliphatic/aromatic copolyesters based on terephthalic acid and poly(L-lactic acid): Synthesis, characterization and hydrolytic degradation

<正>Biodegradable aliphatic/aromatic copolyesters,poly(butylene terephthalate-co-lactate)(PBTL) were prepared via direct melt polycondensation of terephthalic acid(TPA),1,4-butanediol(BDO) and poly(L-lactic acid) oligomer(OLLA). The effects of polymerization time and temperature,as well as aliphatic/aromatic moiety ratio on the physical and thermal properties were investigated.The largest molecular weight of the copolyesters was up to 64100 with molecular weight distribution index of 2.09 when the polycondensation was carried out at 230℃for 6 h.DSC,XRD,DMA and TGA analysis clearly indicated that the degree of crystallinity,glass-transition temperature,melting point,decomposition temperature, tensile strength,elongation and Young's modulus were influenced by the ratio between TPA and OLLA in the final copolyesters.Hydrolytic degradation results demonstrated that the incorporation of biodegradable lactate moieties into the aromatic polyester could efficiently improve hydrolytic degradability of the copolymer even though it still had many aromatic units in the main chains.     

Synthesis, characterization and degradation of well-defined crosslinkable aliphatic polyesters end-capped by biomesogenic units

Novel biodegradable-cum-crosslinkable polyesters end-capped by biomesogenic units, cinnamic acid (CA) and ferulic acid (FA), were synthesized via chain-growth polycondensation in solid-liquid phase. The chemical structure of synthesized polymers was characterized by Fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance spectroscopy (¹H NMR). The composition of polyesters, which was calculated by ¹H NMR, was in agreement with the feed ratios. The thermal properties and crystallinity of polyesters were measured by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), wide angle X-ray diffraction (WXRD) and polarizing-light microscopy (PLM). It was found that the polyesters possessed good crystallinity. Furthermore, the obtained polyesters could be crosslinked with methyl methacrylate (MMA), n-butyl acrylate (BA) and styrene (St) under thermal condition. The crosslinked products possessed degradability in phosphate buffer solution at 37 °C, which might be potentially applied as biomaterials.     

Macrocycles 27: Cyclic aliphatic polyesters of isosorbide

Numerous polycondensations of isosorbide and suberoyl chloride or other aliphatic dicarboxylic acid dichlorides were performed with pyridine as a catalyst and HCl acceptor. The reaction conditions were varied to optimize both the molecular weight and the fraction of cyclic oligo‐ and polyesters. Furthermore, we attempted to obtain the cyclic monomer by catalyzed back‐biting degradation of the molten cyclic polyesters above 220 °C in vacuo. The polyesters were characterized by viscosity and size exclusion chromatographic measurements as well as matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. In selected cases, mixtures of linear and cyclic polyesters were treated with a hot solution of partially methylated β‐cyclodextrin in methanol. This treatment allowed for a selective extraction of the linear chains up to approximately 5000 Da. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3414–3424, 2003     

Synthesis of High Molecular Weight Polyesters via In Vacuo Dehydrogenation Polymerization of Diols

The Milstein catalyst has proven to be highly effective for the conversion of alcohols to esters, as well as alcohols and amines to amides and polyamides. We have recently found that the catalyst's range can be extended to very efficient in vacuo dehydrogenation polymerization of α,ω‐diols to generate polyesters. The gaseous hydrogen byproduct that is produced is easily removed to drive the equilibrium toward product, which leads to the formation of high molecular weight polymer ( up to 145 000 g mol⁻¹). This optimized methodology works well to polymerize diols with a spacer of six carbons or more. Diols with fewer carbons are cyclized to lactone; the dividing point is the dehydrogenation of 1,5‐pentanediol, which leads to a mixture of polyester and lactone. Reported herein is the synthesis and characterization of five aliphatic polyesters prepared via this novel dehydrogenation polymerization approach.     

Synthesis and ring‐opening polymerization of co‐cyclic(aromatic aliphatic disulfide) oligomers

An effective approach was presented for the synthesis of co‐cyclic(aromatic aliphatic disulfide) oligomers by catalytic oxidation of aromatic and aliphatic dithiols with oxygen in the presence of a copper‐amine catalyst. The aromatic dithiols can be 4,4′‐oxybis(benzenethiol), 4,4′‐diphenyl dithiol, 4,4′‐diphenylsulfone dithiol. The aliphatic dithiols can be 1,2‐ethanedithiol, 2,3‐butanedithiol, 1,6‐hexane dithiol. The co‐cyclic(aromatic aliphatic disulfide) oligomers were characterized by gradient HPLC, MALDI‐TOF‐MS, GPC, ¹H‐NMR, TGA, and DSC techniques. The glass transition temperatures of these co‐cyclics ranged from ?11.3 to 56.6°C. In general, these co‐cyclic(aromatic aliphatic disulfide) oligomers are soluble in common organic solvents, such as CHCl₃, THF, DMF, DMAc. These co‐cyclic oligomers readily underwent free radical ring‐opening polymerization in the melt at 180°C, producing linear, tough and high molecular weight poly(aromatic aliphatic disulfide)s. The glass transition temperatures of these polymers ranged from ?3.7 to 107.8°C that are higher than those of corresponding co‐cyclics. Copyright © 2003 John Wiley & Sons, Ltd.     

Butylene copolyesters based on aldaric and terephthalic acids. Synthesis and characterization

The synthesis, characterization, and some properties of new copolyesters analogous to poly(butylene terephthalate) (PBT), based on L ‐arabinaric and galactaric acids, are described. These copolyesters were obtained by polycondensation reaction in the melt of mixtures of methyl 2,3,4‐tri‐O‐methyl‐L ‐arabinarate or methyl 2,3,4,5‐tetra‐O‐methyl‐galactarate and dimethyl terephthalate with 1,4‐butanediol. Their weight‐average molecular weights ranged between 10,000 and 34,000, with polydispersities ranging from 1.4 to 2.2. The composition of all the copolymers was analyzed by NMR, and was found to have a statistical microstructure. All these copolyesters were thermally stable, with degradation temperatures well above 300 °C. The melting temperature and crystallinity decreased in both series, and the glass transition temperature increased and decreased respectively, for the PBTGa and PBTAr series with increasing amounts of aldaric units in the copolyester chain. Only PBT‐derived copolyesters containing a maximum of 30% aldaric units showed discrete scattering characteristic of crystalline material. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1168–1177, 2009     

Synthesis of repeating sequence copolymers of lactic,glycolic, and caprolactic acids

Repeating sequence copolymers of poly(lactic‐co‐caprolactic acid) (PLCA), poly(glycolic‐co‐caprolactic acid) (PGCA), and poly(lactic‐co‐glycolic‐co‐caprolactic acid) (PLGCA) have been synthesized by polymerizing segmers with a known sequence in yields of 50–85% with M_ns ranging from 18–49 kDa. The copolymers exhibited well‐resolved NMR resonances indicating that the sequence encoded in the segmers used in their preparation is retained and that transesterification is minimal. The exact sequences allowed for unambiguous assignment of the NMR spectra, and these standards were compared with the data previously reported for random copolymers. The glass transition temperatures (T_gs) of the PLCA and PGCA copolymers were found to depend primarily on monomer ratio rather than sequence. Sequence dependent T_gs were, however, noted for the PLGCA polymers with 1:1:1 L:G:C ratios; poly LGC and poly GLC exhibited T_gs that differed by nearly 8 °C. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis and characterization of semicrystalline cycloaliphatic polyester/poly(dimethylsiloxane) segmented copolymers

High molecular weight poly(dimethylsiloxane)/semicrystalline cycloaliphatic polyester segmented copolymers based on dimethyl-1,4-cyclohexane dicarboxylate were prepared and characterized. The copolymers were synthesized using a high trans content isomer that afforded semicrystalline morphologies. Aminopropyl-terminated poly(dimethylsiloxane) (PDMS) oligomers of controlled molecular weight were synthesized, end capped with excess diester to form a diester-terminated oligomer, and incorporated via melt transesterification step reaction copolymerization. The molecular weight of the polysiloxane and chemical composition of the copolymer were systematically varied. The polysiloxane segment was efficiently incorporated into the copolymers via an amide link and its structure was unaffected by low concentrations of titanate transesterification catalyst, as shown by control melt experiments. The homopolymer and copolymers were characterized by solution, thermal, mechanical, and surface techniques. The segmented copolymers were microphase separated as determined by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and by transmission electron microscopy (TEM). It was demonstrated that relatively short poly(dimethylsiloxane) segment lengths and compositions were required to maintain single phase melt polymerization conditions. This was, in fact, the key to the successful preparation of these materials. The copolymers derived from short poly(dimethylsiloxane) segments demonstrated good mechanical properties, melt viscosities representative of single phase polymer melts, and were easily compression molded into films. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 3495–3506, 1997     

Synthesis of reactive copolyesters derived from isophthaloyl chloride,bisphenol a,and aliphatic diols with additional reactive groups

Copolycondensation of isophthaloyl chloride, bisphenol A, and aliphatic diols with additional reactive groups were performed in the presence of triethylamine by a trimethyl phosphate/cyclohexane organic/organic interfacial method. The composition of idol and bisphenol A residues in the resulting copolyesters is very close to that in the feed from the initial stage of reaction. The resulting copolyesters with reactive groups can be used for the preparation of various functional polymers. The mechanism of an organic/organic interfacial polycondensation was also discussed. © 1995 John Wiley & Sons, Inc.     

Synthesis and properties of new fluorinated polyarylates derived from 1,1-bis(4-hydroxyphenyl)-1-phenyl-2,2,2-trifluoroethane and aromatic diacid chlorides

A new series of fluorine-containing polyarylates were synthesized by interfacial or high-temperature solution polymerization of 1,1-bis(4-hydroxyphenyl)-1-phenyl-2,2,2-trifluoroethane with six aromatic diacyl chlorides. These polyarylates had inherent viscosities ranging from 0.47 to 1.37 dl/g that corresponded to weight-average and number-average molecular weights (by gel permeation chromatography) of 35,800-72,400 and 30,700-67,700, respectively. All polymers were highly soluble in a variety of solvents, and could afford tough, transparent, and colorless films via solution casting. The glass-transition temperatures of the polymers ranged from 209 to 271 °C. All of them did not show significant decomposition below 450 °C in both nitrogen and air atmospheres.     

Synthesis,thermal, rheological characteristics,and enzymatic degradation of aliphatic polyesters with lignin‐based aromatic pendant groups

This research aims to produce lignin‐based biodegradable polyesters with improved thermal quality. A series of aliphatic polyesters with lignin‐based aromatic side groups were synthesized by conventional melt‐polycondensation. Decent molecular weight (21–64 kg mol^?1) was achieved for the polymerizations. The molecular structures and thermal and mechanical properties of the obtained polyesters were characterized. As a result, the obtained polyesters are all amorphous, and their glass‐transition temperature (T_g) depends on the size of the pendant aromatic group (31–51 °C). Furthermore, according to the TGA results, the thermal decomposition temperatures of the polyesters are all above 390 °C, which make them superior compared with commercial biodegradable polyesters like polylactic acid or polyhydroxyalkanoates. Finally, rheological characteristics and enzymatic degradation of the obtained polyesters were also measured. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2314–2323     

Synthesis, properties and enzymatic hydrolysis of biodegradable alicyclic/aliphatic copolyesters based on 1,3/1,4-cyclohexanedimethanol

This study synthesizes a series of cyclohexanedimethanol (CHDM)-based alicyclic/aliphatic copolyesters (PBSCs) using succinic acid, 1,4-butanediol and 1,3/1,4-CHDM at various molar ratios to investigate the effects of these compositions on crystallinity, biodegradability and the mechanical properties of PBSCs. The PBSCs were characterized using proton nuclear magnetic resonance, gel permeation chromatography, wide-angle X-ray diffraction, differential scanning calorimeter and thermogravimetric analysis. Biodegradability was evaluated by enzymatic hydrolysis with a lipase from Pseudomonas cepacia. The mechanical properties of PBSCs were determined using a tensile testing machine.Experimental results reveal that the PBSCs containing 1,3/1,4-CHDM in total diol with less than 50 mol% are crystallizable, while those containing 1,3/1,4-CHDM with more than 50 mol% are amorphous. The biodegradability test results suggest that PBSCs can be classified as surface-eroding polymers with a random endo-type scission. Surface hydrophilicity of PBSCs was the predominant effect on enzymatic hydrolysis, not crystallinity.     

Syntheses of aliphatic polyesters catalyzed by lanthanide triflates

Polycondensations of 1,6‐hexane diol and sebacic acid were conducted in bulk with addition of a lanthanide triflate as acidic catalyst. With exception of promethium triflate all lanthanide triflates were studied. A particularly low molecular weight was obtained with neodym triflate and the best results with samarium triflate. With Sm(OTf)₃ weight average (M_w) values up to 65 kDa (uncorrected SEC data) were achieved after optimization of the reaction conditions. Comparison of these results with those obtained from bismuth, magnesium, and zinc triflates, on the one hand, and comparison with the acidities of all catalysts, on the other, indicates that the esterification mechanism involves complexation of monomer by metal ions. Preparation of multiblock copoly(ether ester)s failed due to insufficient incorporation of poly(tetrahydrofuran) diols. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 170–177, 2009     

Synthesis and liquid crystalline properties of new amide‐modified poly(1,4‐cyclohexanedimethylene terephthalate)

New series of cycloaliphatic poly(ester‐amide)s, poly(1,4‐cyclohexanedimethyleneterephthalate‐co‐1,3‐cyclohexanedimethylene terephthalamide), were synthesized through solution polymerization route. The compositions of ester/amide units in the copolymers were varied from 0 to 100% by varying the amount of 1,4‐cyclohexanedimethanol and 1,3‐cyclohexanebis(methylamine) in the feed. The structures of the polymers were confirmed by NMR and FTIR, and the molecular weights were determined by inherent viscosity. The composition analysis by NMR reveals that the reactivity of the diamine toward the acid chlorides is lowered than that of diol, which results in the formation of more ester content in the poly (ester‐amides). The thermal analysis indicate that the new poly(ester‐amide)s having less than 10 mol % of amide linkages are thermotropic liquid crystalline from 200 to 250 °C and a thread like nematic phases are observed under the polarizing microscope. WXRD studies suggest that the liquid crystalline domains promote the nucleation process in the polyester chains and increases the percent crystallinity of the poly(ester‐amide)s. The glass transition temperature of the copolymers initially increases with increase in amide units because of the presence of nematic phases and subsequently follows the Flory–Fox behavior. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 42–52, 2006     

Thermally stable liquid crystalline thermosets based on aromatic copolyesters: Preparation and properties

The synthesis and physical properties are described for a thermally stable liquid crystalline (LC) thermoset based on all aromatic ester units. The persistence of the liquid crystalline phase throughout the curing process was monitored with polarizing optical microscopy. The applicability of these new liquid crystalline thermosets has been evaluated for use as an adhesive for bonding metals, namely titanium. The failure of the adhesive bonds always occurs within the polymer; thus it can be inferred that bonding at the polymer-metal interface is very good. This strong interfacial bonding is attributed to low cure shrinkage and CTE matching of the underlying substrate by the LC resins. The cohesive properties and strength of the cured resin can be greatly enhanced by the addition of filler materials. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35:1061–1067, 1997     

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     

Polymer thermal and acoustic properties using heterodyne detected transient grating technique

We investigated the acoustic and thermal features of a polymeric system by a heterodyne detected transient grating technique. We studied two polymers characterized by different molecular weights. Transient grating experiments could reveal a reliable series of information on sound velocity, acoustic damping time, and thermal diffusion of the polymers. The temperature and molecular weight dependence of the polymer acoustic and thermal properties are reported. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011