Vigilancia Tecnológica

Polylactide (PLA)?based reversible/dynamic polymer networks were synthesized by coupling 4?arm PLA stars containing reversible tetraphenylethane (TPE) groups in the core using diisocyanate. Star?shaped PLAs with molecular weights of 3200 and 6400?g/mol were obtained by the original method involving UV coupling of linear PLAs containing benzophenone moieties in the chain middle. The efficient formation of networks with gel content close to 100% was confirmed by FTIR spectroscopy. Networks with different densities of reversible groups exhibited tensile strength in the range of 35–50?MPa. Their reversible character was demonstrated by stress relaxation measurements performed at different temperatures (120–150°C). The prepared networks were capable of very fast stress relaxation due to radical exchange reactions between TPE groups placed in crosslinks, in contrast to a reference network without TPE groups. It was shown in the repairing experiment that networks were capable of processing.