Reaction Kinetics and Morphological Changes of Reactive Polymer/Polymer Interface
Jin Kon Kim, Hwang Yong Kim, Unyong Jeong
Department of Chemical Engineering, POSTECH
Republic of Korea

Keywords: interface, rheology, reaction kinetics

---

In this study we investigated the reaction kinetics by a convenient but useful method – rheology– to characterize the interface between two immiscible blends with a reactive compatibilizer. We made an attempt to correlate changes of interface roughness with rheological properties. The blend systems employed in this study was mono-carboxylated polystyrene (PS-mCOOH) and an poly(methyl methacrylate-ran-glycidylmethacrylate) (PMMA-GMA). PS-mCOOH was synthesized by an anionic polymerization and PMMA-GMA by a free radical polymerization. We prepared two plates of each polymer using compression molding with a smooth surface molder, then put one upon another. As soon as these two plates are put intode a rheometer under nitrogen environment, the torque and moduli were obtained with welding or reaction time at different temperatures.
Through the analysis of this modulus change with reaction time, we estimated interfacial reaction kinetics. Three stages (stage I, stage II and stage III) of reaction are proposed. The increment of modulus in stage I can be correlated to the extent of reaction. In the stage II, we analyzed the plateau value of modulus relating the chain diffusion. We also showed that increment of modulus in stage III was due to by roughened interface. The change of the interfacial roughness between two plates with reaction time was investigated by transmission electron microscopy, and atomic force microscopy (AFM) after selective removal of unreacted PS-mCOOH layer. At long times of the reaction, the interface became pinched-off and then micelles were formed in the PMMA phase.