On volume changes during homopolymerization of polymer networks accessed via “Temperature modulated optical refractometry”

•Simultaneous access to volume shrinkage and thermal volume expansion behaviour.•Chemically induced dynamic glass transition due to homopolymerization.•Competition between molecular mechanisms during homopolymerization of epoxy.•Influence of initiator concentration on volume changes during homopolymerization.•Initiator concentration enhanced morphological diversity during homopolymerization. This study investigates the homopolymerization of a diglycidyl ether of Bisphenol A resin using 1-Methylimidazole as an initiator and provides a new perspective on volume changes and cross-linking reactions via “Temperature Modulated Optical Refractometry” (TMOR) under isothermal conditions. It is shown that the chemical reaction process is divided into an initiation regime, a homopolymerization regime and the chemically induced glassy state. The simultaneous access to the chemically induced volume changes and thermal expansion via TMOR allows to clearly distinct between the three different stages of polymerization and easily determine the region of the (dynamic) glass transition. Also, insights into the statistcial variety of the polymer network formation are provided. [Display omitted]