Polyether-polyester and HMDI Based Polyurethanes: Effect of PLLA Content on Structure and Property

Lei Shi,Jin Zhu,Han Hu,Ruo-Yu Zhang,Zhao-Bin Tang,Yu-Bin Wang,Wu-Bin Ying,Ya-Qian Guo,Wen-Qin Wang

doi:10.1007/s10118-019-2283-3

Abstract

Thermoplastic poly(ether-ester-urethane)s were synthesized from poly(L-lactide) diols (PLLA diols), polytetrahydrofuran diol (PTMG diols), 4,4′-dicyclohexylmethane diisocyanate (HMDI), and 1,4-butanediol (BDO) by a two-step reaction, and the morphology and property of the resultant TPU could be adjusted by varying the PLLA contents. The soft segment was composed of PLLA and PTMG diols. By controlling the percentage of PLLA in the soft segment, the glass transition temperature and mechanical properties of the polyurethanes could be regulated. Based on the FTIR spectrum, we found that two kinds of hydrogen bonding existed individually in soft matrix and hard domain. The hydrogen bonding in soft matrix was unstable, which could be destroyed during elongation. With in situ stretching WAXS and SAXS experiments, we found that the PLLA crystal was destroyed and the PLLA domain oriented along the stretch direction. Finally, we proposed a schematic model to illustrate the microstructures of these elastomers before and after stretch.

Highlights

Thermoplastic elastomers (TPE) are block copolymers of which the microphase can be separated into hard and soft domains
Thermoplastic poly(ether-ester-urethane)s were synthesized from poly(L-lactide) diols (PLLA diols), polytetrahydrofuran diol (PTMG diols), 4,4′-dicyclohexylmethane diisocyanate (HMDI), and 1,4-butanediol (BDO) by a two-step reaction, and the morphology and property of the resultant Thermoplastic polyurethane (TPU) could be adjusted by varying the PLLA contents
Synthesis of PLLA Diol and PLLA-PUs A series of PLLA-PU polymers containing PLLA diol and PTMG diol as the soft segment were prepared via a two-step reaction (Scheme 2)

Summary

Introduction

Thermoplastic elastomers (TPE) are block copolymers of which the microphase can be separated into hard and soft domains. Gu et al.[25] synthesized PLLA-based polyurethanes with HMDI as the hard segment, and the obtained sample showed high elastic modulus (around 850 MPa) but low elongation at break of 4%.

Results

Conclusion