Advanced thermosets based on thiol-isocyanate chemistry

Identificador:  TDX:3167

Handle: https://hdl.handle.net/20.500.11797/TDX3167

Autors:  Gamardella, Francesco

Resum:
In this work, the potentiality of poly(thiourethane) (PTU) thermosets has been exploited, starting from the study of the viability of the “thiol-isocyanate” reaction under acidic and basic conditions. Using basic catalyst, the thiol-isocyanate reaction is too fast, and the system is difficult to process. Thus, we proposed the use of a thermally activated latent base, to obtain a temporal and kinetic control of the curing processes. In addition, we investigated their use as smart materials, thanks to their narrow thermal transitions, which allow quick movements and rapid change in their properties. Therefore, we suggested a possible application of poly(thiourethane) in the fabrication of smart mechanisms for autonomous control, simulating an open-valve application. We have also implemented a novel dual-curing procedure to tailor the material characteristics and improve the processing. It is based on the combination of thiol-isocyanate and thiol-epoxy click reactions, activated sequentially by temperature. The main focus of the thesis was centred on the development of dynamic crosslinked networks (CAN)s, which can be efficiently remoulded and recycled. First, we demonstrated the dynamic capacity of the thiourethane group by using model compounds. Once it was shown that poly(thiourethane)s can be considered as a new type of CANs, these materials were prepared using a tin catalyst