Polymer, Vol.131, 252-262, 2017
Molecular and structural analysis &ITvia&IT hydrodynamic methods: Cationic poly(2-aminoethyl-methacrylate)s
Pharmaceutically relevant cationic linear poly(2-aminoethyl-methacrylate)s were synthesized by reversible addition-fragmentation chain transfer polymerization resulting in a homologous series of the homopolymers in a wide range of molar masses (10,000 < M < 130,000 g mol(-1)) and relatively narrow dispersities (D: 1.3 +/- 0.4). The polymers were studied in 0.2 M NaCl and 0.2 M NaOH in water, applying combined analytical approach comprising of complementary hydrodynamic and optical methods such as analytical ultracentrifugation, intrinsic viscosity, translation diffusion, flow birefringence and asymmetric flow field-flow fractionation (AF4) as well as standard characterization technique (SEC). The efforts were focused on the evaluation of solution (solvation), molecular (absolute molar masses), conformational (equilibrium rigidity, diameter of the polymer chain) and optical (anisotropy of optical polarizability of the monomer unit) characteristics of the polymers. Consequently the absolute values of the molar masses were determined by the sedimentation-diffusion analysis and AF4 resulting in well consistent results. The corresponding scaling relationships in 0.2 M NaCl water ([eta] = 0.0031 x M-0.83; s(0) = 0.0324 x M-0.39; D-0 = 3,909 x M-0.64) show linear trends in whole range of molar masses revealing random coil conformation of the macromolecules. Conformational characteristics were determined in 0.2 M NaCl (equilibrium rigidity A = 5.3 +/- 1.5 nm) and 0.2 M NaOH (A = 1.3 +/- 0.1 nm) revealing an influence of uncompensated charges on the polymer conformation. (C) 2017 Elsevier Ltd. All rights reserved.
Keywords:Cationic polymers;Poly(2-aminoethyl-methacrylate);Sedimentation;Analytical ultracentrifugation;Viscosity;Asymmetric flow field-flow fractionation;Solution properties;Characterization