A new family of dual-curable poly(hydroxyamine)-poly(ether) thermosets based on off-stoichiometric amine-epoxy formulations has been prepared and characterized. The first curing stage was a self-limiting click epoxy-amine polycondensation with an excess of epoxides and the second stage was an anionic homopolymerization of the unreacted epoxy groups, initiated by a latent base. The curing process was sequential with storage stable intermediate materials. The latency of these partially-cured intermediate materials was established not only by a thermally activated base generator, but also by the vitrification of the formulations. The intermediate and final materials exhibit a wide range of properties depending on the relative contribution of both curing stages. Intermediate materials can either be shape conformable solids, or liquids that are applicable as adhesives. Fully cured materials exhibit shape-memory effect.

Dual-curing, that is, the combination of two different polymerization processes taking place simultaneously or sequentially in a curing process, is a highly advantageous technology for the processing of thermosetting systems [1,2] because of its versatility and flexibility. A significant added value of sequential dual curing is possibility of controlling the curing process sequence and the intermediate and final network structures and properties [3-5]. This has potential application in multi-stage processing of one-pot formulations, where materials can be partially pre-cured before their storage, and with tailored material properties for the final application [4-7]. Processing or assembly and the final properties can be achieved whenever desired by using heat or UV light, depending on formulation chemistry, to initiate the final curing stage. Click-type reactions are commonly used in dual-curing formulations [1], in combination with other click [8,9] or non-click reactions [3,5]. Many dual-curable systems are based on acrylate reactions [2,5], although systems based on epoxy curing chemistries such as off-stoichiometric thiol-epoxy [3] or epoxyamine [4,10] formulations, or other epoxy systems [11], are also gaining interest in the recent years. We recently developed a novel off-stoichiometric epoxy-amine system, with excess epoxy groups and latent reactivity in the intermediate state [4]. The first curing reaction was a self-limiting epoxy-amine condensation that takes place at moderate temperatures until exhaustion of reactive amine groups. In the presence of a suitable initiator such as a nucleophilic tertiary amine [10], the excess of epoxy groups can undergo anionic homopolymerization at higher temperatures. However, in this recent work we employed a latent thermal base for the epoxy homopolymerization [4], which ensured at least 7 weeks of storage stability at 30 °C for intermediate materials after the completion of the epoxy-amine reaction. Different materials, coming from a wide range of formulations with different amine-epoxy ratios and tailored intermediate and final properties, were analyzed and characterized, but the curing kinetics of Time-temperature-transformation (TTT) diagram of a dual-curable off-stoichiometric epoxy-amine system with latent reactivity Núria Areny