Synthesis by self-condensing AGET ATRP and solution properties of arborescent poly(sodium 2-acrylamido-2-methyl-N-propane sulfonate)

Randomly branched (arborescent) poly(sodium 2-acrylamido-2-methyl-N-propanesulfonates) (NaPAMPS) were synthesized via self-condensing vinyl polymerization using activators generated by electron transfer atom transfer radical polymerization (AGET ATRP). The controlled self-condensing AGET ATRP of NaAMPS was realized in the presence of 2-(2-bromopropionyloxy)ethyl acrylate (BPEA) as a branching monomer (inimer) in water/pyridine (35-50% of Py) mixed solvents. The content of BPEA in the reaction feed was varied from 10 to 30 wt% allowing the synthesis of NaPAMPS with different degree of branching. SEC determined molecular weight of the prepared NaPAMPS was M_w = 94 000-120 000 g/mol, and the accompanying polydispersity index PDI ranged from 1.84 to 2.47. The definite evidence of highly branched structure of NaPAMPS was provided by the dependence of radius of gyration R_g on weight-average molecular weight M_w with characteristic slope a = 0.38-0.42, and by small-angle X-ray scattering (SAXS) analysis. Molecular parameters, conformation and dynamics of the branched NaPAMPS in dilute salt-free solutions and in the presence of a salt were elucidated by static and dynamic light scattering and SAXS.