Polymeric scaffolds with a double pore structure

In this work polymeric scaffolds with macropores in the shape of cylindrical channels aligned in a microporous polymer matrix were obtained. Polymer networks of different hydrophilicity were obtained with the same pore architecture: poly(hydroxyethyl methacrylate) (representative of a very hydrophilic polymer), poly(ethyl acrylate) (hydrophobic) and poly(ethyl acrylate-co-hydroxyethyl methacrylate) (a 50/50 random co-polymer with intermediate hydrophilicity) net-P(EA-co-HEMA). The macroporous structure was obtained by using poly(acrylonitrile) fibres as porogen, while the microporous matrix was produced by phase separation during polymerisation of the monomers diluted in ethanol. Morphology, equilibrium water content and water diffusion properties of the macroporous sponges are compared with the corresponding non-porous networks. The pores collapse when ethanol is evaporated from the swollen samples at room temperature. The pores of the PHEMA hydrogels reopen when the samples are immersed in liquid water, but this does not occur in the hydrophobic networks. Nevertheless, progressive substitution of ethanol by water produces PEA and co-polymer samples swollen in water with an open pore structure.