H. Kricheldorf, Q. Zang, Gert Schwarz
Nov 1, 1982
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Journal
Polymer
Abstract
Abstract Synthesis of poly(3-hydroxybenzoate) were conducted in three ways: (a) condensation of the novel monomer, 3-(trimethylsiloxy)benzoyl chloride in bulk and in solution, (b) bulk condensation of 3-acetoxybenzoic acid, (c) condensation of 3-hydroxybenzoic acid by means of phosphorus reagents in solution. The bulk condensation of 3(trimethylsiloxy)benzoyl chloride gave the best results with respect to both yields (89–99%) and molecular weights ( Mn = 10 000–14 000). Because amorphous poly(3-hydroxybenzoate) is soluble in various solvents the molar weights could be determined by both vapour pressure osmometry and 1 H n.m.r. endgroup analyses. Crystalline poly(3-hydroxybenzoate) was only obtainable by solvent induced crystallization; yet not by annealing. Glass transition ( Tg = 145°C) and melting point ( Tm =181°–185°C) were determined by means of differential scanning calorimetry and torsion pendulum. Branched poly(3-hydroxybenzoate) was prepared by condensation of 3-(trimethylsiloxy) benzoyl chloride and 3,5-(bistrimethylsiloxy) benzoyl chloride. Thus, for the first time a branched polycondensate was obtained which did not crosslink regardless of the conversion.