Determination of the conformation of polymers in the amorphous solid state and in concentrated solution by neutron diffraction

From the coherent neutron scattering on dilute solid solutions of the ordinary polymer within the deuterated polymer, conformation parameters of polymer chains in amorphous solid states can be determined. In this way vitreous poly(methyl methacrylate) (PMMA) has been investigated. The chains form unperturbed coils and the radius of gyration is very near to the corresponding value in dilute solutions of the same polymer in the low molecular θ-solvent butyl chloride. The same principle of measurement has been applied to concentrated solutions of PMMA in D-acetone. The solutions contained 50% polymer, the main part of which (98% and more) was deuterated so that the system was optically dilute for neutron scattering on H-PMMA. A monotonic dependence of the radius of gyration and of thermodynamic parameters on the concentration has been found. A first result is presented for a mixture of two polymers. A dilute solid dispersion of poly(α-methylstyrene) (PMS) within D-PMMA has been investigated at M_w = 250 000. The samples are limpid. The PMS forms micelles of 16 molecules (weight average). The radius of gyration of the micelles, r_z is 170 Å.