Efficient hydrosilylation reaction in polymer blending: An original approach to structure PA12/PDMS blends at multiscales

Abstract

An in situ amide hydrosilylation reaction was developed to prepare polyamide 12 (PA12)/polysiloxane copolymers by reactive blending. This reaction is focused on the addition of hydrogenosilane groups (SiH) from polysiloxane to the carbonyl group from the PA12 amide function. To evidence this carbonyl hydrosilylation onto an amide based polymer, an approach on model compounds (use of N-methylpropionamide) was carried out. The mechanism and kinetics were investigated with multinuclear NMR (1H, 13C and 29Si). During kinetics studies, the concentration of N-silylated copolymers can reach 70 mol% after 2 h reaction at 100 °C.Amide hydrosilylation reaction was extended to the reactive blending of polyamide 12 with PDMS-SiH under molten processing conditions. Formation of a structured blend was investigated by rheology and electronic microscopy at different scales. The impact of both shearing and reaction on the final morphology was deeply studied and the interfacial enhancement by compatibilization was confirmed. As a result, the dispersion of PDMS domains decreased from 3 to 4 μm to around 0.8 μm in diameter forming submicronic morphology. Furthermore, it was possible to control the dispersion of PDMS at different scales by modifying the physico-chemical parameters (molar mass and functionality) of both components.