Degradability of cross-linked polyurethanes based on synthetic polyhydroxybutyrate and modified with polylactide

Joanna Brzeska,Magda Morawska,Agnieszka Tercjak,Marek Kowalczuk,Wanda Sikorska,Maria Rutkowska

doi:10.1007/s11696-017-0218-4

Abstract

In many areas of application of conventional non-degradable cross-linked polyurethanes (PUR), there is a need for their degradation under the influence of specific environmental factors. It is practiced by incorporation of sensitive to degradation compounds (usually of natural origin) into the polyurethane structure, or by mixing them with polyurethanes. Cross-linked polyurethanes (with 10 and 30%wt amount of synthetic poly([R,S]-3-hydroxybutyrate) (R,S-PHB) in soft segments) and their physical blends with poly([d,l]-lactide) (PDLLA) were investigated and then degraded under hydrolytic (phosphate buffer solution) and oxidative (CoCl2/H2O2) conditions. The rate of degradation was monitored by changes of samples mass, morphology of surface and their thermal properties. Despite the small weight losses of samples, the changes of thermal properties of polymers and topography of their surface indicated that they were susceptible to gradual degradation under oxidative and hydrolytic conditions. Blends of PDLLA and polyurethane with 30 wt% of R,S-PHB in soft segments and PUR/PDLLA blends absorbed morewater and degraded faster than polyurethane with low amount of R,S-PHB.

Highlights

Last decades have brought a significant increase in the amount and kind of renewable substrates used to obtain polyurethanes (PUR)
Two cross-linked polyurethanes were synthesized as shown in Scheme 1
Polyurethanes were named according to the percentage of R,S-PHB in the soft segments, which was 10 and 30% by weight for PUR10 and PUR30, respectively

Summary

Introduction

Last decades have brought a significant increase in the amount and kind of renewable substrates used to obtain polyurethanes (PUR). Cross-linked polyurethanes are modified chemically by introducing bio-based substrates, such as: saccharides (Okoli et al 2014; Zia et al 2016a), oils (Arniza et al 2015; Ionescu et al 2016), bio-based polyesters (Zhang et al 2015), and others (Silva et al 2009; Datta and Głowinska 2014) into the PUR structure. Properties of polyurethanes can be modified by physical blending of linear and cross-linked PUR with compounds existing in nature or obtained by the biosynthesis, like peptides (Zuber et al 2015), polysaccharides (Saralegi et al 2014; Zia et al 2016b; Brzeska et al 2015a) and polyhydroxyalkanoates (Martınez-Abad et al 2016).

Methods

Results

Conclusion