Adhesive curing is a process by which the adhesive hardens and polymerizes completely. It is crucial for the curing process to guarantee a strong and durable chemical bond as the bonds between adhesive and substrate may weaken and even fail to occur otherwise.
Dr Javier Gómez Sánchez recently defended his industrial doctoral thesis at IQS, in which he proposes an innovative on-demand adhesive curing solution based on self-sustaining frontal polymerization initiated by UV-LED light, viable on an industrial scale and adaptable to multiple applications.
Currently, there is a growing interest foron-demand UV curing systems due to their greater versatility and efficiency compared to conventional methods such as thermal curing. In this process, ultraviolet light is used to initiate a photochemical reaction that generates a network of crosslinked polymers with strong adhesion power. The industrial applications for this system are vast due to the speed and efficiency of curing, but the curing technology presents an important limitation: the inability to cure dark areas or materials with complex and thick geometries where light cannot penetrate adequately. This is called the big dark curing problem.
Within this context, Dr Javier Gómez Sánchez conducted his doctoral thesis, “Bringing light to the front: a novel on-demand UV-LED curing technology for advanced adhesives and composite manufacturing,” as part of the Materials Engineering Group (GEMAT) at IQS. His thesis was supervised by Dr Salvador Borrós Gómez and conducted under the Government of Catalonia’s Industrial Doctorates Plan, co-financed between the IQS School of Engineering (Ramon Llull University) and the company Gloo, a startup launched from within the GEMAT group that is a specialist in the development of high-performance adhesives.
This doctoral thesis proposes an innovative solution: anon-demand curing system based on self-sustaining frontal polymerization initiated by UV-LED light, viable on an industrial scale and adaptable to multiple applications in sectors such as adhesives, composites, and 3D printing.
An innovative curing system with light
The main challenge in Dr Gómez’s research was to overcome the limitations of dark curing and achieve a system that, once activated by light, can continue the curing reaction in a self-sustaining manner without the need for other energy sources to fully complete the curing.
The strategy he followed, called Cationic Induced Cationic Frontal Polymerization (CICFP), offers greater availability and versatility of raw materials than previous approaches. With the energetic inertia generated by the irradiation of light alone, the curing process advances like a domino effect: once started at the first reaction point, the following points are activated continuously, propagating the curing process to reach all the material.
In the first phase, Dr Gómez’s thesis addressed the development of a portfolio ofon-demandUV-curing formulations, both radical and cationic, optimized to improve reactivity, curing depth, and oxygen inhibition in radical systems. These formulations demonstrated their feasibility in industrial applications such as adhesives, composites, and 3D printing. The detailed analysis of these systems made it possible to precisely define the operational limits of conventional UV technology in applications with high thickness or complex geometries in which light cannot access the entire material.
This research made it possible to establish the key criteria and requirements that subsequently guided the development of the CICFP strategy to overcome the limitations of dark curing. The CICFP formulation Dr Gómez designed was optimized and adapted for subsequent implementation in real industrial applications, both in adhesives and in the manufacture of structural composites.
The innovative on-demand curing technology developed in his thesis has been the subject of a European patent application at the Spanish Patent Office.
To conclude, Dr Gómez’s thesis lays the foundation for a new generation of more efficient and sustainableon-demand curing technologies, an innovative solution that addresses the key limitations of traditional UV systems with high application potential in sectors such as automotive, construction, electronics, and additive manufacturing.
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