Polymerization of methyl methacrylate in the presence of tributylborane and aerosil

In this work, we study the polymerization of methyl methacrylate in the presence of 0.3-1.2 wt% aerosil and the following initiators: dinitrile azo-bis-isobutyric acid together with tributylborane; dinitrile azo-bis-isobutyric acid together with tributylborane and 2,5-di-tret-butyl benzoquinone-1,4; tributylborane together with di-tret-butyl peroxy-triphenylstibine. Aerosil introduction alters the polymerization kinetics of methyl methacrylate and the respective IR spectra, indicating an increase in the proportion of syndiotactic polymer. This process is related to the orientation of the monomer and polymer on the filler surface due to adsorption by means of the carbonyl oxygen atom and silicon d-orbitals. Each initiating system has a particular effect on the kinetic curves. The polymerization of methyl methacrylate in the presence of tributylborane proceeds through coordination-radical polymerization in the coordination sphere of the boron atom. Additional coordination disrupts monomer coordination and slows down polymerization. The polymerization of methyl methacrylate in the presence of the tributylborane-p-quinone system combines the routes of coordination-radical polymerization and pseudo-living radical polymerization. The initiating system of tributylborane-di-tret-butyl peroxy-triphenylstibine is characterized by implementation of both physical and chemical adsorption mechanisms. The latter promotes the formation of a composite through covalent bonds between the polymer matrix (polymethyl methacrylate) and the filler (aerosil). An increase in the amount of aerosil up to 10 wt% leads to a corresponding change in the IR spectra of the composites. Laboratory samples were prepared to study the mechanical properties of composites and films. When filled with aerosil, polymethyl methacrylate demonstrate worse deformation properties, which is typical of composite materials. The microhardness of the material varies depending on the initiator used and the grafting type (physical or chemical), correlating with the kinetic data.