Surface-Initiated PLP-SEC of Butyl Acrylate and Styrene from Silica Nanoparticles

The pulsed-laser polymerization size-exclusion chromatography (PLP-SEC) technique has been successfully applied to the measurement of the propagation rate coefficient, k(p) , of the surface-initiated polymerizations of butyl acrylate (BA) and styrene, using the silica-immobilized bipedal initiator 4,4'-azobis(4-cyano-N-(3″-triethoxysilylpropyl)-valeric amide) (ACTA). The molecular weight distribution (MWD) of grafted poly(BA) polymerized at 25 °C was structureless, whereas at 5 °C reaction temperature, the MWD exhibited a typical PLP structure with two inflection points. In case of styrene the SEC trace obtained at 26 °C is well structured and shows four inflection points. The propagation rate coefficients k(p) of the surface-initiated polymerizations were about 22% higher in the case of BA and about 27-28% higher in the case of styrene compared to the IUPAC benchmark data.