Effect of in-situ reactive compatibilization on the structure and properties of SiO2/PEG/PLA shape memory composites.

To address the inherent trade-off between strength and toughness and the issue of PEG migration and exudation commonly observed in polyethylene glycol/polylactic acid (PEG/PLA) plasticized systems, this study introduces γ-glycidoxypropyltrimethoxysilane (GPTMS)-modified nano-SiO2 (mSiO2) as a functional filler, yielding SiO2/PEG/PLA (SPP) composites with good mechanical properties, suppressed PEG migration and exudation, and excellent shape memory performance. In-situ compatibilization driven by mSiO2 reactions with PLA and PEG optimized the interface, significantly enhancing the comprehensive properties of the SPP composites, thereby endowing the composites with markedly enhanced mechanical properties. The SPP composites achieved a tensile strength of 40.4 MPa and a tensile modulus of 1073.4 MPa, while retaining a high elongation at break of 167.7%. The SPP composites exhibited a confined crystallization mode, and the crystallinity increased to 7.8%, representing an improvement of 36.8% over the neat PEG/PLA blend. In addition, the SPP composites maintained excellent optical transparency, with transmittance exceeding 83% at a wavelength of 550 nm. Attributed to the dual effects of chemical anchoring and physical barrier, the PEG mass retention ratio of the SPP composites increased by 4.1% (compared to the PEG/PLA composites) after heat treatment at 90 °C for 5 days. Furthermore, the SPP composites demonstrated excellent shape memory performance, achieving a shape memory fixity ratio above 94% and a shape memory recovery ratio above 80% when recovered after being pre-strained to 100% strain at 85 °C.