Polyreactions in ordered systems: Polymerization of octadecyl methacrylate in monolayers at the gas–water interface

Abstract

AbstractThe ultraviolet‐initiated polymerization of octadecyl methacrylate (ODMA, octadecyl 2‐methyl‐2‐propenoate) as a monomolecular layer at the gas‐water interface was studied. The polymerization was carried out at 27°C at the nitrogen‐water interface; air inhibits the polymerization. At 27°C the ODMA monolayer exhibits three different states which were characterized by surface pressure‐area diagrams and by surface potential measurements. The ODMA monolayer was polymerized under constant surface pressure in the range between 0 and 10 dyne/cm. The polymerization was followed by recording the contraction of the film. The conversion was determined by comparison of the area per monomer unit during polymerization with the area of mixed monolayers formed from ODMA and poly‐ODMA as well as by infrared spectroscopy. The polymerization in the condensed state of the monolayer (at high surface pressure) is considerably faster than in the expanded state (at low surface pressure). As the polymer has a condensing effect on the monomer in the mixed monolayer, autocatalysis is suggested at low surface pressures. The resulting polymer was studied by x‐ray diffraction. The structure of the freshly collapsed film is determined by the conformation of the polymer at the interface; the data after crystallizing the same sample from the melt point to higher tacticity of the poly‐ODMA prepared in monolayers than that of poly‐ODMA prepared by normal radical polymerization in solution.