Engineering Porous Water-Responsive Poly(PEG/PCL/PDMS Urethane) Shape Memory Polymers

Porous and bulk water-responsive urethane-based shape memory polymers (SMPs) containing poly(ethylene glycol) (PEG), poly(caprolactone), and poly(dimethylsiloxane) are fabricated. The copolymers are processed by electrospinning to achieve porous structures. Shape fixation and recovery are achieved via the solvation and recrystallization of the hydrophilic PEG switching segment. Mechanical testing is performed to determine the SMP functionality. Water uptake rate for porous SMP is found to be higher than bulk SMP partly due to higher surface area for water contact. This enables porous structure water-responsive SMPs to recover faster compared to bulk SMPs. The water-responsive SMP exhibits good extents of shape fixity and shape recovery when immersed in water (approximate to 35 degrees C). Different actuation times can be achieved based on the total surface area and efficiency of water-entry into the polymer.