Investigating the properties of novel poly(2-hydroxyethyl methacrylate-co-methyl methacrylate) hydrogel hollow fiber membranes

Poly(2-hydroxyethyl methacrylate-co-methyl methacrylate) hydrogel hollow fiber membranes were synthesized by a novel centrifugal-spinning methodology that resulted in new asymmetric wall morphologies, which in turn affected the mechanical and transport properties. Hollow fiber membranes were formed after polymerizing the comonomers, 2-hydroxyethyl methacrylate and methyl methacrylate, in an aqueous system under centrifugal forces. The concentration of methyl methacrylate in the comonomer and the concentration of redox initiators were investigated for their effects on membrane morphology, water content, Young's modulus, and diffusive transport. Both monomer composition and initiator concentration impacted the resulting asymmetric membrane morphology, which varied from a macroporous sponge to a microporous gel to a homogeneous gel. The hollow fiber membranes synthesized herein had equilibrium water contents between 42 and 57%, elastic moduli between 22 and 400 kPa, and effective diffusion coefficients between 10(-7) and 10(-9) cm(2) s(-1) for vitamin B12 and 10 kD dextran. The significant differences in both the moduli and the diffusion coefficients exhibited by these hydrogel membranes reflect differences in their intrinsic microstructures. Synthesis of hydrogel hollow fiber membranes using centrifugal force is a highly dynamic process; the membrane properties can be effectively tailored by controlling phase separation kinetics. These hydrogel hollow fibers are particularly attractive for soft tissue applications, such as nerve guidance channels, where biocompatibility, mechanical strength, and transport properties are determinants of device performance in vivo.