Synthesis and thermodynamics of block copolymers based on a hyperbranched perfluorinated poly(phenylenegermane) and poly(meth)acrylates

The free-radical polymerization of methyl methacrylate and methyl acrylate, when carried out to a conversion of 15-18% in the presence of 15-20 wt % of the hyperbranched perfluorinated poly(phenylenegermane) of the empirical formula [(C6F5)(2)C6F4Ge](n), leads to the binding of 30-40% of the latter polymer via the chain-transfer reaction. The feasibility of this reaction was established with the use of the model compound tetrakis(pentafluorophenyl)germane for the polymerization of methyl methacrylate (C-S = 0.1) and methyl acrylate (C-S = 0.2). Products arising from the polymerization of these monomers in the presence of the hyperbranched polymer are characterized by the bimodal molecular-mass distribution. A low-molecular-mass fraction with M-w = (2-3) x 10(4) was assigned to the one-arm block copolymer, while the high-molecular-mass fraction having M-w = (0.8-1.0) x 10(6) was attributed to multiarm structures resulting from transformations specific to the system under study. When the polymerization of methyl methacrylate in the presence of 20 wt % of the perfluorinated poly(phenylenegermane) was conducted to maximum conversions, the product containing a block copolymer was isolated. For this copolymer, the temperature dependence of heat capacity was studied by precision adiabatic vacuum calorimetry in the 6-350 K range and dynamic scanning calorimetry in the range from 320 to 450 K, thermodynamic characteristics of devitrification of constituent blocks were determined and analyzed, and standard thermodynamic functions were calculated.