Thermo-responsive shape memory behavior of poly(styrene-b-isoprene-b-styrene)/ethylene-1-octene copolymer thermoplastic elastomer blends

Thermally-triggered shape memory polymers (SMPs) are smart materials, which are capable of changing their shapes when they are exposed a heat stimulant. Blending semi-crystalline and elastomeric polymers is an easy and low-cost way to obtain thermo-responsive SMPs. In this work, novel poly(ethylene-co-1-octene) (PEO) and poly(styrene-b-isoprene-b-styrene) (SIS) thermoplastic elastomer blends were prepared via melt blending method. The morphological, mechanical, rheological properties and shape memory behaviours of the blends were investigated in detail. In morphological analysis, co-continuous morphology was found for 50 wt% PEO/50 wt% SIS and 60 wt% PEO/40 wt% SIS (60PEO/40SIS) blends. The shape memory analysis performing by dynamic mechanical analyzer showed that the 60PEO/40SIS blend also exhibited the optimum shape memory performance with 95.74% shape fixing and 98.98% shape recovery. Qualitatively shape memory analysis in hot-water pointed out that the amount of semi-crystalline PEO promotes shape fixing ability of the blends whereas SIS content enhances shape recovery capability. Although the SIS and PEO are immiscible polymers, the blends of them were exhibited good elastomeric properties with regard to tensile strength, toughness, and elongation at break.

Automated summary

Thermally-triggered shape memory polymers (SMPs) can change shape when exposed to heat. Blending PEO and SIS thermoplastic elastomers resulted in a 60PEO/40SIS blend with the best shape memory performance, showing 95.74% shape fixing and 98.98% shape recovery. The presence of semi-crystalline PEO improved shape fixing, while SIS content enhanced shape recovery capability, despite the immiscibility of these polymers.