Aqueous phase size-exclusion-chromatography used for PLP-SEC studies into free-radical propagation rate of acrylic acid in aqueous solution

Pulsed laser polymerization (PLP) in conjunction with analysis of the resulting polymer by size-exclusion-chromatography (SEC) was used to measure propagation rate coefficients, kp, of acrylic acid (AA) in aqueous solution at concentrations of 20 and 40 wt % and temperatures between 2.6 and 28.5 degreesC. Under these conditions, more than 99% of acrylic acid exists in the nonionized form. The molecular weight distribution MWD) of poly(AA) is directly measured by aqueous SEC. The kp values at 20 wt 7( are about 60% higher than at 40 wt %. The activation energy of hp is close to 12.0 kJ . mol(-1) at both concentrations. At 25 degreesC and 20 wt %, k(p) of AA in aqueous solution exceeds 100 000 L . mol(-1).s(-1) which is the highest kp value determined by the PLP-SEC technique so far.