Abstract: | We have analyzed fractionated samples of poly(methacrylic acid) produced in a propagating front for the amount of anhydride that formed and determined that a large percentage of acid groups exist as anhydrides (>20%). By analyzing the samples after cleavage, we found that the molecular weight dropped significantly (from Mn = 1.4 × 105 to Mn = 1.0 × 104). We conclude that the high molecular weights observed previously were the result of intermolecular anhydride formation. Poly(butyl acrylate), which cannot form anhydride bonds, produced in fronts had broad (Mw/Mn = 1.7–2.0) but unimodal molecular weight distributions with Mu < 105. The average molecular weight decreased with increasing initiator concentrations. © 1996 John Wiley & Sons, Inc. |