Mechanosensing on a large scale for safety assessment and damage analysis

Resistance to damage, fracture and failure is critical for high performance polymers, especially so in safety applications where they protect equipment or human life. In this project we investigate the use of molecular mechanochemistry tools for the measurement and analysis of mechanical impact in high performance polymers and their composites. While typically performed in a laboratory setting, these measurements hold promise for studying damage in large scale realistic samples. For this we will to develop fluorescent imaging techniques and chemistry, necessary to produce mechanoresponsive samples. This proposal will also draw correlations between imaging and mechanical testing, which can ultimately allow us to study realistic samples and recover the history of the impact they have sustained during operation.

Eindrapportage

Within this project, we investigated the feasibility of developing mechanoresponsive and mechanosensitive
high-performance polymers for application in composite materials. The primary objective was to validate
preparation strategies for such materials and assess their potential for damage detection and early failure
prevention in realistic mechanical applications, including composite structures and enclosures.
Throughout the study, several practical and fundamental limitations were identified, providing important
insights into future development pathways for mechanoresponsive glassy thermoset composites. These
findings can be grouped into two main areas.
A. Practical aspects of thermoset preparation. Experimental work focused on optimizing curing strategies,
monomer selection, and processing conditions to achieve uniform polymerization and reliable
mechanosensing behavior. A key result was the distinct performance difference between styrene- and PMMAbased epoxy matrices. PMMA systems demonstrated superior curing behavior, yielding fully cured, non-sticky
samples with improved structural integrity, whereas styrene-based systems frequently exhibited incomplete
curing. These results indicate that synthetic modifications required to introduce mechanosensitive molecules
into existing industrial polymer formulations may be incompatible with standard processing protocols. Oxygen
inhibition was identified as a major source of inconsistency, particularly in open or mold-based systems such
as dogbone samples. Curing in sealed environments under inert atmosphere significantly reduced oxygen
interference and improved reproducibility.
B. Small-molecule mechanochemistry in glassy thermosets. While preliminary data confirmed that
activation of mechanosensitive molecules in polymeric glasses is possible, the extent of activation was strongly
reduced in highly crosslinked thermosets, limiting their sensing utility. Thermal curing using AIBN enabled
more homogeneous polymerization and was the only method that consistently allowed spiropyran activation
under UV irradiation. However, such curing protocols are impractical for large-scale composite manufacturing
and remain limited to laboratory-scale applications. Furthermore, cobalt-based promoters, though effective for
curing, were found to potentially inhibit mechanophore activation, highlighting an inherent trade-off between
curing efficiency and mechanosensing performance