Synthesis and Properties of Functionalized Poly(ε-caprolactone); Chain Polymerization Followed by Polycondensation in One Pot with Initiator and Catalyst in One Molecule. Synthesis and Molecular Structures
Krzysztof Kałużyński, Julia Pretula, Piotr Lewiński, Sławomir Kaźmierski, Stanisław Penczek
Abstract
Poly(ε-caprolactone) and polylactide are biocompatible and biodegradable polymers. Both are hydrophobic, and their backbones do not contain reactive groups. The existing methods of functionalization are mostly based on copolymerization with functional comonomers that require additional syntheses. In the method of functionalization described in this work, special end groups are introduced that allow, after chain polymerization of ε-caprolactone (CL), the following step, in one pot, namely polycondensation. Chain polymerization was initiated/catalyzed by hydroxymethylphosphonic acid. Since one of the end groups contains two acidic groups, one is used in polycondensation with the hydroxyl group from the other end group and the other one, becoming less reactive, is introduced to the polymer chains. Thus, polymer chains contain phosphoacidic groups along the chain. When, for example, CL was the first chain polymerized to an oligomer of the molar mass ∼3 × 103 g·mol–1, its further polycondensation resulted in polymers with a molar mass approaching ∼105 g·mol–1, with ∼30 acidic groups along the statistical chain.