Block copolyetheresters. V. Low‐temperature properties of thermotropic block copolyetheresters

Tsai, Hong‐Bing; Lee, Da‐Kong; Liu, Jung‐Liang; Tsao, Yii‐Soong; Tsai, Ruey‐Shi

doi:10.1002/(sici)1097-4628(19960207)59:6<1027::aid-app17>3.3.co;2-h

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“…The tan δ peak from −34 to 42 °C related to loss modulus peak is contributable to the glass transition temperature of the PEEs. 31,33 Worth mentioning is that the magnitude of maximum relaxation in the tan δ curve reflects the relative amount of amorphous materials in the copolymers. 26 As the hard segment content in the PEEs increased, its peak position shifted to higher temperature and the peak intensity decreased.…”

Section: Acs Sustainable Chemistry and Engineeringmentioning

confidence: 99%

Scalable Synthesis of Poly(ester-co-ether) Elastomers via Direct Catalytic Esterification of Terephthalic Acid with Highly Active Zr–Mg Catalyst

Song

Huang

et al. 2018

ACS Sustainable Chem. Eng.

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The poly(ester-co-ether)s (PEEs) comprising poly(butylene terephthalate) and poly(tetramethylene glycol) (PTMG) segments were cost-efficiently synthesized by direct esterification of terephthalic acid (TPA) and 1,4-butandiol (BDO)/PTMG with M n of 1000 in one feeding step by a unique nontoxic Zr−Mg catalyst that is designed and synthesized in our laboratory, avoiding undesirable eco-hazardous cocatalyst and byproducts that must be produced when terephthaloyl chloride (TPC) and dimethyl terephthalate (DMT) were chosen. The structure of the Zr− Mg catalyst and PEEs was systematically analyzed by high-resolution 1 H NMR, ATR-FTIR spectroscopies, and X-ray diffraction. The size-exclusion chromatography suggested that the weight-average molecular weight of the PEEs reaches up to 60 600 g/mol. In particular, the ether-segment retention, molecular weight, melt processability, and mechanical properties of the PEEs are significantly higher by Zr−Mg catalyst than by Ti−Mg and traditional tetrabutyl titanate (TBT) catalysts. DSC and DMA analyses revealed that the PEE copolymers obtained by the Zr− Mg catalyst have random segment distribution, glass transition temperature down to −34 °C, and good elasticity and strong toughness at ambient temperature. TBT is an efficient catalyst for the polycondensation between TPC/BDO or DMT/BDO prepolymers and PTMG for synthesizing excellent PEEs, unfortunately accompanying with the usage of toxic and expensive bases and the formation of hazardous HCl or methanol byproducts. This study confirmed that TBT is not powerful enough to achieve high-molecular-weight and thus tough PEEs via the environ-benign direct polycondensation among TPA, BDO, and PTMG anymore, while the Zr−Mg catalyst developed here is active enough to catalyze the direct polycondensation without compromise or toxic discharge. Furthermore, the TPA-based PEE elastomers demonstrate potential to replace current eco-unsafe elastomers like rubbers, polyurethane, polyolefin, and TPC-/DMT-based PEEs.

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Section: Acs Sustainable Chemistry and Engineeringmentioning

confidence: 99%