Conformation of high-molecular-weight poly(L-valine) in solid state.

Poly(L-valine) in various degrees of polymerization was prepared from the N-carboxyanhydride of L-valine. The high-molecular-weight polymer was fibrous and capable of forming an oriented film when cast from trifluoroacetic acid solution. The comformations were examined by Raman spectroscopy. The Raman and infrared spectra of high-molecular-weight polymer were quite different from those of low-molecular-weight and tri-fluoroacetic-acid-treated high-molecular-weight polymers. The spectral data in the amide A, I, II, III, and V regions indicated that high-molecular-weight poly(L-valine) is possibly in the alpha-helical conformation, while low-molecular-weight poly(L-valine) and high--molecular-weight poly(L-valine) treated with trifluoroacetic acid are in the beta-conformation.