Synthesis of isosorbide-based polycarbonates via melt polycondensation catalyzed by quaternary ammonium ionic liquids

A series of quaternary ammonium ionic liquids(ILs)were synthesized and employed as catalysts for the production of poly(isosorbide carbonate)(PIC)from diphenyl carbonate and isosorbide via a melt polycondensation process.The relationship between the anions of the ILs and the catalytic activities was investigated,and the readily‐prepared IL tetraethylammonium imidazolate(TEAI)was found to exhibit the highest catalytic activity.After optimizing the reaction conditions,a PIC with a weight‐average molecular weight(Mw)of25600g/mol was obtained,in conjunction with an isosorbide conversion of92%.As a means of modifying the molecular flexibility and thermal properties of the PIC,poly(aliphatic diol‐co‐isosorbide carbonate)s(PAIC)s were successfully synthesized,again using TEAI,and polymers with Mw values ranging from29000to112000g/mol were obtained.13C NMR analyses determined that the PAIC specimens had random microstructures,while differential scanning calorimetry demonstrated that each of the PAICs were amorphous and had glass transition temperatures ranging from50to115°C.Thermogravimetric analyses found Td‐5%values ranging from316to332°C for these polymers.Based on these data,it is evident that the incorporation of linear or cyclohexane‐based diol repeating units changed the thermal properties of the PIC.

Preparation and characterization of biodegradable aliphatic-aromatic copolyesters/nano-SiO_2 hybrids via in situ melt polycondensation

In situ melt polycondensation was proposed to prepare biodegradable aliphatic-aromatic copolyesters/nano-SiO2 hybrids based on terephthalic acid （TPA）, poly（L-lactic acid） oligomer （OLLA）, 1,4-butanediol （BDO） and nano-SiO2. TEM and FT-IR characterizations confirmed that TPA, OLLA and BDO copolymerized to obtain biodegradable copolyesters, poly（butylene terepbthalate-co-lactate） （PBTL）, and the abundant hydroxyl groups on the surface of nano-SiO2 provided potential sites for in situ grafting with the simultaneous resulted PBTL. The nano-SiO2 particles were chemically wrapped with PBTL to form PBTL/nano- SiO2 hybrids. Due to the good dispersion and interfacial adhesion of nano-SiO2 particles with the copolyester matrix, the tensile strength and the Young＇s modulus increased from 5.4 and 5.6 MPa for neat PBTL to 16 and 390 MPa for PBTL/nano-SiO2 hybrids with 5 wt.% nano-SiO2, respectively. The mechanical properties of PBTL/nano-SiO2 hybrids were substantially improved.

Synthesis and Characterization of Novel Hydrolytically Degradable Polyesters

Six novel hydrolytically degradable polyesters were synthesized from thiodipropionic acid(TDPA)and five diols by melt polycondensation,and characterized by FT-IR,1H NMR,gel permeation chromatography,differential scanning calorimetry and thermogravimetry analysis.The polystyrene-equivalent number-average(Mn)and weight-average molecular weight(Mw)of these polyesters ranged from 4900-11100 Da and 7900-20879 Da,respectively,with PDI values of 1.48-1.98.The melting point varied from 62.3-127.9℃,and the 50%mass-loss temperature ranged between 387-417℃.The degradation of these polyesters was studied in terms of relative weight loss in distilled water at different pH.Weight losses of 14%-26%were obtained at pH 7.0,26%-38%at pH 6.0,and 32%-43%at pH 8.3 over a 20-week period.The ecotoxicity study suggested that safety of the synthesized polyesters for the eisenia foetida.These results indicate that these polyesters have a combination of good thermal and degradability behaviors,which can be tailored through selection of the diol monomers used in the synthesis.

Synthesis,Characterization and Water Absorption Analysis of Highly Hygroscopic Bio-based Co-polyamides 56/66

This study aims to develop highly hygroscopic bio-based co-polyamides(CPs)by melt co-polycondensation of polyamide(PA)56 salt and PA66 salt with varying molar fractions.The functional groups and the chemical structure of the prepared samples were determined by Fourier transform infrared(FTIR)spectroscopy and proton nuclear magnetic resonance(^(1)H-NMR)spectroscopy.The relative viscosity was determined with an Ubbelohde viscometer.The melting behavior and the thermal stability of CPs were investigated by differential scanning calorimetry(DSC)and thermogravimetric analysis(TGA).Furthermore,the water absorption behavior of CP hot-pressed film was studied.The results reveal that the melting point,the crystallization temperature and the crystallinity of CPs firstly decrease and then increase with the molar fraction of PA66 in CPs.The copolymerization of PA56 with PA66 leads to an obvious increase in water absorption.The CPs with PA66 molar fraction of 50%possess a high saturated water absorption rate of 17.6%,compared to 11.6%for pure PA56 and 7.8%for pure PA66.

BIODEGRADABLE ALIPHATIC/AROMATIC COPOLYESTERS BASED ON TEREPHTHALIC ACID AND POLY(L-LACTIC ACID):SYNTHESIS,CHARACTERIZATION AND HYDROLYTIC DEGRADATION

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 and Characterisation of Sorbitol Based Copolyesters for Biomedical Applications

In this investigation we report on the synthesis and characterisation of certain polyester elastomers namely as Poly（Sorbitol succinate-co-ethylene glycol succinate） （PSSEG）, Poly（sorbitol succinate-co-butane diol succinate） （PSSBD） and Poly（sorbitol succinate-co-hexane diol succinate） （PSSHD） by carrying out catalyst free melt polycondensation.. The synthesised polyesters were characterised by solubility, FT-IR, -H NMR and 13C NMR spectral methods. The thermal properties were analysed by differential scanning calorimetry and thermogravimetric analysis. The mechanical properties evaluated for the polyester films in the tensile mode shows that the polymer has characteristics of elastomers and stiff thermosets. We demonstrate that the chemical structure, physical integrity and mechanical property of synthesized copolyester can be controlled by simply changing the monomers and suit them for the requirements of various biomedical and soft tissue engineering applications.

Functionalization of polyhedral oligomeric silsesquioxanes with bis(hydroxyethyl) ester and preparation of the corresponding degradable nanohybrids

One novel difunctionalized polyhedral oligomeric silsesquioxanes （POSS） derivative was designed and synthesized by a convenient method with high yield. 1H NMR and P＇r-IR characterizations suggested that Michael addition reaction successfully took place between 2-hydroxyethyl acrylate （HEA） and aminopropylisobutyl POSS （POSS-NH2） under mild conditions, which finally formed bi（hydroxyethyl） ester-functionalized POSS derivatives （BH-POSS）. Due to the similar functional groups and high reactivity, BH-POSS could be easily incorporated into the main-chain of biodegradable aliphatic-aromatic copolyesters PBTL via in situ melt polycondensation to prepare corresponding degradable nanohybrids with high mechanical properties.