Tuning the Mechanical Properties of BIEE‐Crosslinked Semi‐Interpenetrating, Double‐Hydrophilic Hydrogels

Abstract

Double‐hydrophilic, semi‐interpenetrating (semi‐IPN) hydrogels are synthesized by encapsulating hydrophilic polyvinylpyrrolidone (PVP) linear chains in structure‐defined 1,2‐bis‐(2‐iodoethoxy)ethane (BIEE)‐crosslinked (poly(2‐(dimethylamino)ethyl methacrylate) (pDMAEMA) hydrogels. A series of semi‐IPN double‐hydrophilic hydrogels are prepared in which the pDMAEMA/BIEE content is kept the same and only the PVP content is varied, from 0 up to 33 wt%. The mechanical properties of the water‐swollen hydrogels are experimentally evaluated under unconfined compressive loading conditions, while a nonlinear hyperelastic constitutive equation is used to predict their mechanical response. No significant difference is found in the mechanical response of the semi‐IPN PVP/pDMAEMA/BIEE hydrogel containing 5 wt% PVP compared to the pDMAEMA/BIEE analog, however, for greater loading percentages (15 and 33 wt% of PVP), the semi‐IPN hydrogels exhibit less stiffness/higher ductility. Furthermore, in vitro biocompatibility studies are carried out for the pDMAEMA/BIEE and the semi‐IPN PVP/pDMAEMA/BIEE, indicating that both the formulations exhibit no toxicity in cultured cells.