Dipentaerythritol

As a thermo-responsive elastomer, the membrane polymer (6-arm 96% PCL-co-04% PGMA) was synthesized by ring-opening polymerization of ε-caprolactone (CL; Sigma-Aldrich, MO, USA) and glycidyl methacrylate (GMA; Sigma-Aldrich). Briefly, dipentaerythritol (0.5 mmol, Sigma-Aldrich), hydroquinone (2.1 mmol, Sigma-Aldrich), and distilled CL (329 mmol) were prepared in a 3-necked flask. The mixture was stirred at 110 °C for 10 min. GMA (21 mmol) was added, and the reaction was allowed to proceed for 10 min. Then, a solution of 1,5,7-triazabicyclo [4.4.0] dec-5-ene (Sigma-Aldrich) and anhydrous acetonitrile (Sigma-Aldrich) (3.5 mmol) was added and reacted at 110 °C for 6 h under a nitrogen atmosphere. The product was dissolved in chloroform and precipitated using cold diethyl ether (Sigma-Aldrich). The final product, 6-arm 96% PCL-co-04% PGMA (%: molar ratio), was obtained after vacuum drying for 24 h.

Commercial unsaturated polyester resin, 77 polyester molding resin, and methyl ethyl ketone peroxide (MEKP) as initiator were purchased from FIBREGLAST. Dipentaerythritol and zinc acetate were purchased from Sigma‐Aldrich.