Actuator Behaviour of Tailored Poly(thiourethane) Shape Memory Thermosets

Abstract

In this work, a new family of poly(thiourethane) shape memory thermosetting actuators was developed and characterized. These materials can be easily prepared from mixtures of two different aliphatic diisocyanates and a trithiol in the presence of a latent catalyst, allowing an easy manipulation of the formulation. Rheological studies of the curing process confirm the latent character of the formulations. The glass transition temperatures and the mechanical properties can be modified by varying the proportion of diisocyanates (hexamethylene diisocyanate, HDI, and isophorone diisocyanate, IPDI) with stoichiometric amounts of trimethylolpropane tris(3-mercaptopropionate). The shape-memory behavior was deeply investigated under three different conditions: unconstrained, partially constrained, and fully constrained. Tests were performed in single cantilever bending mode to simulate conditions closer to real complex mechanics of thermomechanical actuators under flexural performances. The complex recovery process in single cantilever bending mode was compared with that obtained using tensile mode. The results evidenced that the amount of recovery force in fully constrained conditions, or energy released during the recovery process in partially constrained, can be modulated by simply changing the proportion of both diisocyanates. A simple model based on Timoshenko beam theory was used for the prediction of the amount of work performed. The reported results are an important guideline to design shape-memory materials based on poly(thiourethane) networks, establishing criteria for the choice of the material depending on the expected application.

Analysis of Poly(thiourethane) Covalent Adaptable Network through Broadband Dielectric Spectroscopy

“…Nonetheless, in Figure , the first heating, second heating, and cooling curves are plotted. The glass transition, attributed to the flexible backbone of the HDI-S3, is found around 310 K. This value agrees well with other results for similar networked structures …”

“…The glass transition, attributed to the flexible backbone of the HDI-S3, is found around 310 K. This value agrees well with other results for similar networked structures. 23 …”

“…The subsequent more prominent mass-loss stage is found above 523 K and is associated with the elimination of carbonyl sulfide during the decomposition process of the thiourethane. 23 , 24 Furthermore, the next stage related to the peak around 613 K is attributed to the β-elimination processes of the esters of the thiol structural units. 5 , 7 At last, the mass loss between 673 and 773 K agrees with the degradation of the backbone.…”

“…The glass transition, attributed to the flexible backbone of the HDI-S3, is found around 310 K. This value agrees well with other results for similar networked structures. 23 The thermal stability of the sample was assessed through thermogravimetric analysis (TGA). The samples were subjected to a dynamic thermal program under an oxidative atmosphere.…”

A Brief Overview of Polymers Science and Technology, in Spain

“…Marta Guembe-García José Miguel García, Saúl Vallejos New monomers derived from methacrylamide for amino acid polymer sensors [18] Esther Udabe Maria Forsyth, David Mecerreyes Ionic liquid monomers covalently integrated into an acrylic polymer coating for corrosion inhibition [19] Jorge González-Rodríguez Jaime González-Álvarez, Belén Altava, Santiago, Luis Silica-supported polymeric ionic liquid from a vinylic L-valine monomer and divinylbenzene as the chromatographic stationary phase [20] Javier Quílez-Bermejo Diego Cazorla-Amorós Synthesis of doped polyaniline for mesoporous carbon material [21] Beatriz Martínez-Sánchez Emilia Morallón Syntheis of phosphonated ring-substituted PANIs: electrochemical properties and computational calculations [22] Estefania Fernandez-Bartolome Rodrigo González-Prieto, Reyes Jiménez-Aparicio Coordination polymers from heteronuclear dirhodium-gold anionic complexes. Synthesis and crystal structure [23] Alexandra Muñoz-Bonilla Marta Fernández-García Hidrogels from new 2-hydroxyethyl methacrylate and a methacrylic monomer containing a lateral thiazole group with antimicrobial behavior [24] Francesco Gamardella Angels Serra Organocatalyzed poly(thiourethane) covalent adaptable networks able to be reshaped and recycled [25] Francesco Gamardella Silvia De la Flor New family of shape-memory actuators based on poly(thiourethane) networks: thermomechanical properties and shape-memory ability [26] Cenit Soto Pedro Prádanos, Antonio Hernández…”