Shape memory polymers were formulated using tert-butyl acrylate (tBA) and poly(ethylene glycol) dimethacrylate (PEGDMA), with average molecular weights (Mn) of 550, 750, and 1000 with polymerization being facilitated by photoinitiator 2,2—dimethoxy-2-phenylacetophenone (DMPA). All of the products were obtained from Sigma-Aldrich (St. Louis, MO, USA), except for PEGDMA1000, which was obtained from Polysciences (Warrington, PA, USA) and were used as received. A total of nine polymer solutions were prepared from these monomer components (Figure 1 ).
Monomer mixtures were injected into molds composed of standard microscope slides (Thermo Fisher Scientific, Waltham, MA, USA), separated by a 1.33 mm silicone spacer (Mcmaster-Carr, Elmhurst, IL, USA), and cured under ultraviolet (UV) radiation of wavelength = 365 nm for 20 min, similar to previous methods [29 (link)]. The samples were then removed from the molds and post-cured in an oven at 75 °C overnight, similar to methods done previously [25 (link)].
Monomer mixtures were injected into molds composed of standard microscope slides (Thermo Fisher Scientific, Waltham, MA, USA), separated by a 1.33 mm silicone spacer (Mcmaster-Carr, Elmhurst, IL, USA), and cured under ultraviolet (UV) radiation of wavelength = 365 nm for 20 min, similar to previous methods [29 (link)]. The samples were then removed from the molds and post-cured in an oven at 75 °C overnight, similar to methods done previously [25 (link)].