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Greener routes to HCPK for photopolymerisation identified
A comparative life cycle assessment of six synthetic routes for the photoinitiator 1-hydroxycyclohexyl phenyl ketone (HCPK) identifies the environmentally preferable option and confirms the feasibility of using HCPK in photopolymerisation of poly(vinyl acetate-co-crotonic acid). The study also highlights how process scale-up modelling improves the accuracy of early-stage LCA.
Photoinitiators have long been investigated as alternatives to thermal initiators in polymer synthesis, primarily to reduce polymerisation temperatures and associated heat consumption. The synthesis of poly(vinyl acetate-co-crotonic acid) provides a suitable model system to explore photoinitiation strategies. In this study, the performance of several commercial photoinitiators was experimentally evaluated, with 1-hydroxycyclohexyl phenyl ketone (HCPK) demonstrating superior effectiveness compared to other tested alternatives, including the thermal initiator benzoyl peroxide under the same conditions.
Building on these performance results, a comprehensive life cycle assessment (LCA) was carried out to compare six alternative synthetic routes for producing HCPK. The analysis considered three different data sources: laboratory-scale experimental data, advanced process calculation and software-assisted modelling. The latter two were used as representative of industrial-scale production, allowing meaningful comparisons across scales.
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Scale-up modelling shapes environmental impact profiles
Among the six investigated synthesis pathways, the route involving an initial α-chlorination of cyclohexyl phenyl ketone followed by nucleophilic substitution emerged as the environmentally preferable option. As anticipated, environmental impacts generally decreased when moving from laboratory-scale modelling to software-assisted industrial-scale modelling, reflecting typical process optimisation gains at larger production scales.
Overall, the work demonstrates that the synthesis of poly(vinyl acetate-co-crotonic acid) is feasible through photopolymerisation using HCPK, with clear performance advantages over conventional thermal initiators. From a methodological perspective, the study also shows that while laboratory-scale LCA is a valuable preliminary screening tool, more accurate early-stage environmental assessment is achieved through industrial-scale process simulation. The findings provide useful guidance for both formulators and process engineers aiming to align photopolymerisation technologies with sustainability targets.
Source: Arfelli, F. et al., Addressing sustainability in photopolymerization: comparative LCA study of six synthetic routes of 1-hydroxycyclohexyl phenyl ketone as photoinitiator for copolymer applications. Green Chemistry 28 (28), 11815–11825 (2026).
