Origin of micro-scale heterogeneity in polymerisation of photo-activated resin composites

Slobodan Sirovica, Johanne H. Solheim, Maximilian W. A. Skoda, Carol J. Hirschmugl, Eric C. Mattson, Ebrahim Aboualizadeh, Yilan Guo, Xiaohui Chen, Achim Kohler, Dan L. Romanyk, Scott M. Rosendahl, Suzanne Morsch, Richard A. Martin, Owen Addison*

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review


    Photo-activated resin composites are widely used in industry and medicine. Despite extensive chemical characterisation, the micro-scale pattern of resin matrix reactive group conversion between filler particles is not fully understood. Using an advanced synchrotron-based wide-field IR imaging system and state-of-the-art Mie scattering corrections, we observe how the presence of monodispersed silica filler particles in a methacrylate based resin reduces local conversion and chemical bond strain in the polymer phase. Here we show that heterogeneity originates from a lower converted and reduced bond strain boundary layer encapsulating each particle, whilst at larger inter-particulate distances light attenuation and monomer mobility predominantly influence conversion. Increased conversion corresponds to greater bond strain, however, strain generation appears sensitive to differences in conversion rate and implies subtle distinctions in the final polymer structure. We expect these findings to inform current predictive models of mechanical behaviour in polymer-composite materials, particularly at the resin-filler interface.
    Original languageEnglish
    Article number1849
    JournalNature Communications
    Issue number1
    Publication statusPublished - 15 Apr 2020

    Bibliographical note

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    Funding: S.S. was funded by the Global Challenges Studentship from the Science and Technology Facilities Council (award no. ST/L502510/1).


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