A polylactide (PLA)-based network was prepared using functional PLA bearing pendant benzophenone (BP) groups capable of reacting between themselves. Benzophenone functional groups were introduced into PLA-based macromolecules through lactide cationic copolymerization with a pre-prepared epoxide derivative. A low molecular weight copolymer (Mn ∼3000) with a low fraction of the epoxide (∼20 mol.%) and on average of three pendant benzophenone groups was obtained. This copolymer was further coupled using aliphatic diisocyanate to achieve a threefold increase in molecular weight. The resulting copolymer was subjected to UV irradiation in solution to produce a crosslinked film through the linking reaction between benzophenone moieties, forming tetraphenylethane (TPE) thermally reversible groups as crosslinks. The PLA-based network with reversibly forming crosslinks was analyzed through rheology investigations, which indicated its dynamic character. Independently of the original method of preparing the dynamic network with not explored so far reversible groups, TPE groups were utilized as the initiating groups for the exemplary vinyl monomer polymerization, namely acrylonitrile. It was demonstrated that new polymer chains could be easily introduced inside the PLA-based polymer network through network heating in the presence of a vinyl monomer. This demonstrates the development of a new approach to PLA-based dynamic network modification, providing an additional possibility for the preparation of novel PLA-based materials.