Monomer reactivity ratios for lauryl methacrylate–isobutyl methacrylate in bulk free radical copolymerization

Abstract

AbstractStatistical copolymers of isobutyl methacrylate and lauryl methacrylate were prepared by free radical bulk copolymerization at 70 °C using 2,2′‐azobisisobutyronitrile as initiator. The synthesis of these copolymers was investigated over a wide composition range at low conversion levels. Copolymer compositions were determined from the C, H and O contents obtained by elemental analysis. The monomer reactivity ratios and the 95% individual confidence intervals and 95% joint confidence intervals were calculated by the Fineman–Ross, Ezrielev–Brokhina‐Roskin, Kelen and Tüdös, Extended Kelen and Tüdös methods and a linear iterative method proposed by Mao and Huglin. The estimation process was performed by applying non‐linear techniques based on Marquardt optimization, ordinary least‐squares (OLS) and generalized least‐squares approaches and the results were compared. Monomer reactivity ratios and monomer partition coefficients were also analysed on the basis of the bootstrap models by applying the non‐linear least‐squares approach. Good agreement between experimental and calculated copolymer compositions was obtained. The results show that this copolymerization system is strictly describable by the simple bootstrap terminal model (SBTM) and accurate monomer reactivity ratios can be obtained. The monomer sequence distributions were also calculated using the monomer reactivity ratios obtained from SBTM. Copyright © 2003 Society of Chemical Industry