The Paper on Photo-Curable Triazinetrione Composites is Published in the Journal of Applied Polymer Science

Researchers at KTH, led by Prof. Michael Malkoch and driven forward by Dr. Jorge San Jacinto Garcia, have developed a new generation of photo-curable composites with tunable degradation properties for the bone fixation patch domain. Their work has been published in the Journal of Applied Polymer Science as “Photo‐Curable Triazinetrione Composites with Tunable Degradation for Fracture Stabilisation and Flexible Thin‐Film Applications”

The materials address key limitations of conventional metal fracture fixation implants, including rigid geometry, lack of customisation, and absence of degradability. Designed as injectable, on-demand hardening composites, the new formulations can showcase bone-like mechanical properties while adapting to complex fracture geometries.

To enhance degradability, two routes were evaluated. Firstly, hydrolytically cleavable ester linkages were introduced into the polymer backbone. Secondly, inert hydroxyapatite (HA) was substituted with bioresorbable fillers such as bioactive glass (BG) and tricalcium phosphate (TCP). Different combinations of ester-containing monomers and fillers were systematically evaluated. The incorporation of a higher content of ester bonds resulted in materials with increased degradability to the expense of flexural modulus. This allows for the casting of flexible, degradable films that have potential for use in tissue engineering applications.

Optimisation of the filler content and type, as well as the ester linkages content allowed for an increased degradation rate, while still maintaining high flexural modulus (up to 6.4 GPa) and thermal stability above physiological temperature (45 °C). Preliminary cytotoxicity testing confirmed excellent cell viability. In mechanical fixation tests using synthetic and cadaver bone models, the degradable composites demonstrated comparable or superior load-bearing capacity to their non-degradable counterparts. These results highlight the potential of ester-containing TATO composites as a first class of biodegradable, high-performance alternatives for orthopaedic use. Further in-vivo evaluation is warranted to assess long-term degradation and clinical applicability.

“This research is highly important, as our innovative approaches will enable more patient-personalised treatments. Moreover, they address several limitations associated with traditional metal plates and screws. These include achieving mechanical properties more closely aligned with those of natural bone tissue, preventing soft tissue adhesion, and offering degradability.” Says Dr San Jacinto Garcia. “One of the most groundbreaking aspects of this work is the replacement of screws as the anchoring method. Previously, the technique was constrained by the size and quality of the bone. By using adhesive primers, we expand the applicability of bone-like composites to thinner bones and even to those compromised by osteoporotic processes.”

The paper describing the photo-curable composites can be accessed via https://onlinelibrary.wiley.com/doi/10.1002/app.57068?af=R. The data used in the paper has also been uploaded to an open data repository, which can be found at https://zenodo.org/records/13887411.