A novel segmented block copolymer, containing polyethylene glycol segment and GlyAlaGlyAla sequence derived from B. mori silk, has been prepared as a model for silk-based materials using both solution and interfacial techniques. Inherent viscosity, size exclusion chromatography, and light-scattering measurements gave molecular weight between M-w 34,000-39,000. Evidence for phase separation was provided by differential scanning calorimetry, which gave two Tg's at -57 degrees C and 111 degrees C, and transmission electron microscopy, which showed a morphology in which the peptide domain, estimated to be about 20-50 nm, was dispersed in the continuous polyether phase. Solid-state FTIR spectroscopic results showed that the polymer contained both parallel and antiparallel beta-sheet stacks, and that the solution-polymerized material has the higher beta-sheet content. This was further confirmed by C-13 NMR, which gave about 80% total beta-sheet content for the solution-polymerized product and about 40% for the polymer obtained by interfacial polymerization.