Synthesis And Properties Of Thermoplastic Poly(Ester Urethane) Through A Non-Isocyanate Route

In this paper, a series of biodegradable thermoplastic poly(ester urethane)s (TPEUs) were synthesized through a non-isocyanate route. First, several polyester oligomers were prepared under environment-friendly catalyst. Second, different prepolymers of bis(hydroxyethyloxy carbonyl amino)hexane (BHCH),i.e. (PrePBHCHs), were prepared through transurethane polycondensation of BHCH. Finally, melt polycondensation of the polyester oligomers and BHCH or PrePBHCHs was conducted. A series of TPEUs were synthesized. The properties of TPEUs can be regulated by changing starting materials, molecular weight of polyester oligomer and PrePBHCHs, and molar ratios. The main contributions are described as follows:1、Poly(butylene terephthalate) oligomers terminated with hydroxyl groups (HO-PrePBT-OHs) were synthesized through melt polycondensation of dimethyl terephthalate with excessive butanediol. Then, a series of poly(butylene adipate-co-butylene terephthalate) prepolymers terminated with hydroxyl groups (HO-PrePBAT-OHs) were synthesized from the polycondensation of HO-PrePBT-OH, adipic acid (AA) and excessive butanediol. Finally, transurethane polycondensation of BHCH with HO-PrePBAT-OHs was conducted, and a series of aromatic-aliphatic thermoplastic poly(ester urethane)s-PBATUs were prepared. The PBATUs were characterized by FT-IR,1H-NMR, DSC, WAXS and tensile test. PBATUs show intrinsic viscosity ([η]) from 0.66 to 0.90 dL·g-1, melting point (Tm) from 117.80℃ to 178.30℃, good thermal stability with initial decomposition temperature (Ti) up to 284.30℃ (above the Tm 100℃). The butylenes terephthalate (BT) units were the crystallization source of PBATUs. Polycondensation decreased the crystallinity slightly. In PBATUs, the butylenes adipate (BA) units acted as soft segments. Increase of BA content led to the decrease of tensile strength and the increase of elongation at break. Introducing BHCH as hard segments made the tensile strength of polymer increased slightly and the elongation at break increased greatly. By changing BT/BA molar ratios, thermoplastic plastics with high tensile strength of 26.91 MPa and elongation at break of 82.77% or thermoplastic elastomers with tensile strength of 14.93 MPa and elongation at break of 799.17% were obtained.2、Apoly(butylene adipate) prepolymer terminated with hydroxyl groups (HO-PrePBA-OH) was synthesized through melt polycondensation of AA with excessive butanediol. Three PrePBHCHs were prepared through self-polymerization of BHCH.A series of aliphatic segmented thermoplastic poly(ester urethane)s (PBAUs) and elastomers were synthesized via transurethane polycondensation of the PrePBA with PrePBHCHs.The TPEUs exhibited Mn from 17275 to 23262, Mw from 36047 to 51074, Tm from 91.80℃ to 113.23. The PBAUs were crystalline polymers and the crystallization was both affected by BA and BHCH segments. The PBAUs had good thermal stability with Ti ranging from 274.67℃ to 287.33℃(100℃ above their Tm), tensile strength between 13.98 MPa and 18.81 MPa, and the elongation at break from 246.27% to 629.35%.Micro-scale phase separation in PBAUs leads to the resilience of up to 77.50%.