Multi-block polyesters demonstrating high elasticity and shape memory effects

Journal article

Polyester block polymers containing polylactide have garnered significant attention as renewable, degradable alternatives to traditional elastomers. However, the low glass transition of the PLA blocks limits the upper-use temperatures of the resulting elastomers. To improve the thermal performance, we explore a series of multi-block polyesters composed of poly(ε-decalactone) (PDL) and poly(cyclohexene phthalate) (PCHPE). These materials are prepared using switchable polymerization catalysis followed by chain extension, the strategy involves: i) alternating ring-opening copolymerization (ROCOP) of cyclohexene oxide and phthalic anhydride, ii) -decalactone ring-opening polymerization (ROP), and iii) isocyanate coupling of the telechelic triblocks to increase molar mass. The resulting multi-block polyesters are amorphous and the blocks are phase separated; glass transition temperatures are ~ -45 °C and 100 °C. They show thermal resistance to mass loss with Td5% ~ 285 °C and higher upper use temperatures compared to alternative aliphatic polyesters. The nanoscale phase behaviour and correlated mechanical properties are highly sensitive to the block composition. The sample containing PCHPE = 26 wt% behaves as a thermoplastic elastomer with high elongation at break (εb > 2450%), moderate tensile strength (σb = 12 MPa) and low residual strain (εr ~ 4%). It shows elastomeric behaviour from -45 to 100 °C and has a processing temperature range of ~170 °C. At higher PCHPE content (59 wt%), the material has shape memory character with high strain fixation (250%) and recovery (96%) over multiple (25) recovery cycles. The multi-block polyesters are straightforward to prepare and the methods presented here can be extended to produce a wide range of new materials using a other epoxides, anhydrides and lactones. This first report on the thermal and mechanical properties highlights the significant potential for this class of polyesters as elastomers, rigid plastics and shape memory materials.

Authors: Zhu, Y; Radlauer, M; Schneiderman, D; Shaffer, M; Hillmyer, M

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Chemical Society
• Journal: Macromolecules
• Volume: 51
• Issue: 7
• Pages: 2466–2475
• Publication date: 2018-03-19
• Acceptance date: 2018-03-06
• DOI: 10.1021/acs.macromol.7b02690
• EISSN: 1520-5835
• ISSN: 0024-9297