Macromolecular transport through nanostructured and porous hydrogels synthesized using the amphiphilic copolymer, PCL-b-PEO-b-PCL

We have studied macromolecular transport through nanostructured and porous hydrogels. These hydrogels were produced by (1) synthesizing poly(ε-caprolactone-b-ethylene oxide-b-ε-caprolactone) (PCL-PEO-PCL) block copolymers, (2) crosslinking the block copolymer in aqueous solutions at high concentrations, and (3) degrading the PCL blocks by hydrolysis. Lamellar morphologies of the PCL-b-PEO-b-PCL were observed using Small Angle X-ray Scattering (SAXS) and Atomic Force Microscopy (AFM). The regions formerly occupied by PCL domains have no spanning PEO chains and thus should allow fast transport of macromolecules without significant entanglement. This work presents Fluorescence Recovery After Photobleaching (FRAP) data showing that macromolecular diffusivities are higher in these nanostructured materials than in comparable homogeneous PEO hydrogels prepared under the same crosslinking conditions to yield similar crosslink density. These materials offer a route to high macromolecular mobility, and so may be useful in bioengineering areas such as drug delivery and protein separation.