Dilute solution behavior of poly(vinylidene fluoride). Intrinsic viscosity and light scattering studies

Light scattering and viscosity measurements of poly(vinylidene fluoride), (PVF2), were made in three solvents; namely, N,N‐dimethylacetamide (DMA), N,N‐dimethylformamide (DMF), and N‐methyl‐2‐pyrrolidone (NMP). The following relations between the intrinsic viscosity, [η], (in deciliters per gram) and the weight‐average‐molecular weight, M̄w, were obtained: [η] = 17,8·10−6 M̄ (in DMA at 125°C), [η] = 31,7·10−6 M̄ (in DMF at 125°C) and [η] = 48,8·10−6 M̄ (NMP at 125°C). Treatment of the data by the method of Inagaki et al. indicates that the steric factor, σ, is 1,89, 1,65 and 1,60 in DMA, DMF, and NMP respectively. It is found that the root‐mean‐square radius of gyration of the chain measured by light scattering is in good agreement with the root‐mean‐square radius of gyration of the chain calculated by using the viscosity theory of Inagaki et al. The relations between the root‐mean‐square radius of gyration of the chain in the three solvents and the molecular weight obtained were as follows: 〈S̄2〉 = 2,95·10−1 M̄ (in DMA); 〈S̄2〉 = 8,13·10−2 M̄ (in DMF) and 〈S̄2〉 = 2,82·10−1 M̄ (in NMP). From the estimation of the second viral coefficient, A2, and the values of B (cf. Eq. (6)) obtained from viscosity data, it is concluded that the polymer chains are more extended in DMA than in DMF and NMP.