Polymerization of p‐methacrylyloxybenzoic acid in mesomorphic and in liquid states

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Abstract
The polymerization of p‐methacrylyloxybenzoic acid in the liquid crystalline state (dissolved in p‐cetyloxybenzoic acid) and in the liquid state (solution in dimethylformamide) was studied. The polymerization of p‐methacrylyloxybenzoic acid in the liquid phase is characterized by regularities usual in the radical homogeneous polymerization of vinyl monomers in isotropic mediums. At temperatures above 100°C. incomplete conversion is observed, which is explained by polymerization–depolymerization equilibrium. The polymerization of p‐methacrylyloxybenzoic acid in the liquid crystalline phase is characterized by a considerable increase in polymerization rate and polymer molecular weight (Mw = 6 × 105) over the liquid‐phase polymerization in DMFA (Mw = 5 × 104). The polymerization rate in liquid crystalline state does not depend on conversion degree and remains constant up to 70–75% conversion. The rate of polymer formation depends only slightly on the initial monomer concentration at the change of [M0] from 1.3 to 3 moles/l. The molecular structure of the mesomorphic phase also creates favorable thermodynamic conditions for the formation of macromolecules. At all T < Tceiling practically complete conversion of monomer into polymer is observed, which is impossible with homogeneous polymerization in solution.