Zirconocene-Mediated Cationic Copolymerization of n-Butyl and 2-Phthalimidylethyl Vinyl Ethers: Reactivity Ratios, Thermal Analysis, and Degradation Kinetics

Abstract

This study reports the synthesis of the novel statistical copolymers comprising of n-butyl vinyl ether, BVE, and 2-phthalimidylethyl vinyl ether, PEVE, via a nonconventional cationic polymerization technique involving activated zirconocene complexes. Initially, the research was focused in finding the best experimental conditions to obtain the statistical copolymerization of the two monomers, utilizing bis(η⁵-cyclopentadienyl)dimethyl zirconium, Cp₂ZrMe₂, in conjunction with tetrakis(pentafluorophenyl)borate dimethylanilinium salt [B(C₆F₅)₄]^–[Me₂NHPh]⁺, as the initiation system. The statistical analysis of the P(BVE-co-PEVE) products, along with the calculation of the monomers’ reactivity ratios via various linear graphical methods and the COPOINT program demonstrated that an azeotropic copolymerization occurred in toluene at 25 °C. Regarding the thermal analysis, the glass transition temperatures, T_g, were determined by differential scanning calorimetry, DSC, and were subsequently correlated with a number of theoretical models, thereby enabling the prediction of these T_g values. The thermal stability of the copolymers was investigated by means of thermogravimetric analysis, TGA, and differential thermogravimetry, DTG, at six distinct heating rates. The derived data were processed within the framework of the Ozawa–Flynn–Wall, OFW, and Kissinger–Akahira–Sunose, KAS, methodologies in order to study the kinetics of thermal decomposition. Finally, the PEVE-based copolymers were subjected to basic hydrolysis, resulting in the formation of the corresponding copolymers of BVE and 2-amino-ethyl vinyl ether, AEVE, which were also studied by TGA and DTG analysis. These materials can be further employed for further chemical transformations and the synthesis of more complex macromolecular architectures and, as amphiphilic and biocompatible compounds are possible candidates for the biomedical applications.