Behaviour of poly(β‐hydroxybutyric acid) in dilute solution

Abstract The refractive indices of poly(β‐hydroxybutyric acid) (PHB) at four wavelengths have been determined via different procedures. Viscometric and light scattering measurements have been made on solutions of eight samples of PHB ( M w = 20·9 × 10 3 −929 × 10 3 g mol −1 ) in 2,2,2‐trifluoroethanol. From the dependences of intrinsic viscosity and of radius of gyration on molar mass, the conformation of PHB in dilute solution is shown to be that of a random coil. The findings are discussed in relation to existing conflicting evidence on the conformation of this polymer.