Molecular Dimension and Interaction Parameters of Polyacrylamide in Water‐N,N‐Dimethylformamide Mixtures

Abstract

The intrinsic viscosities [η] of polyacrylamide (PAM) having different average molecular weights are measured in various mixtures of water (good solvent) and N, N dimethyl formamide (DMF, nonsolvent) at different temperatures. The observed results show a significant variation of cosolvency as a function of solvent composition (ϕ_DMF). The nature of curves in [η] vs. ϕ_DMF plot at different temperatures indicates the existence of two antagonistic effects. The unperturbed dimensions (K_θ) of the polymer are determined by a number of methods, which agree well with each other. The temperature coefficient of unperturbed dimension (K′), molecular extension factors (α_n), characteristic ratio (C_α) and chain rigidity (σ) are evaluated and the effects of temperature, solvent composition are discussed. The volume related parameter V_E and shape factor ν were also computed, which shows the shape of polymer molecules to be more or less spherical in solution.

Keywords:

• polyacrylamide (PAM)
• intrinsic viscosity [η]
• unperturbed dimension (UD)
• cosolvent
• volume related parameter (V_E)
• temperature coefficient of UD (K′)

Acknowledgments

Thanks are due to Council of Scientific and Industrial Research (CSIR), New Delhi for financial grants. One of the authors (B. Debnath) is thankful to the University Grants Commission, New Delhi for fellowship support. G. Bit wishes to thank the authorities of Government Champhai College, Mizoram, India for granting study leave.

Additional information

Notes on contributors

G. Bit

Permanent Address: G. Bit, Government Champhai College, Champhai, Mizoram, India.