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Fluorescence Microscopy Reveals Structure-Property Relationships and Polymer Dynamics in Biocomposites



Quinn Easter, Shawn Chen, Jeremiah Woodcock, Amanda Souna, Sindhu Seethamraju, Jan Obrzut, Douglas M. Fox, Stephan J. Stranick, Jeffrey Gilman


OBJECTIVES: Developing the next generation of materials for use in restorative work requires a multifaceted approach. While mimicking the properties of the tooth, currently available dental composites and porcelains eventually fail and require replacement. Renewable, biocompatible restorative composites would be advantageous because they can be obtained from renewable resources and serve as a temporary filler while the tooth is repaired by the body. Self-assembled biobased materials present attractive alternatives to existing nonrenewable materials. However, methods are needed to understand their composition differences and reveal their intrinsic properties. The aim of this study was to interrogate self-assembled cellulose nanocrystal (CNC) films cross-linked with polyetherdiamines to provide a feasibility approach to using fluorescence lifetime imaging microscopy (FLIM). METHODS: Sulfated CNCs were ion-exchanged with a reactive epoxytrimethylammonium or nonreactive tetramethylammonium cation. Polyetherdiamines containing 2 reactive amine groups were used. A water-sensitive dye was synthesized from one polyetherdiamine and Rhodamine B to monitor fluorescence lifetimes (FL). Films were self-assembled into Bouligand structures at controlled rates using fixed quantities of CNCs and dye but varying quantities of polyetherdiamines. RESULTS: Films with reactive CNCs had differences in FL that corresponded to the reactivity in the samples. Films with nonreactive CNCs showed few differences by FLIM, indicating reactivity was responsible for FLIM differences. Adding more polyetherdiamines increased reactivity as seen by narrowed FL distributions. A model was described wherein longer polyetherdiamines could cross-link adjacent lamellae in reactive films, narrowing distances between lamellae; in nonreactive films, however, no reaction was possible, resulting in wider distances. CONCLUSIONS: FLIM demonstrated the ability to resolve reactivity heterogeneity on submicron length scales. This work will assist in developing next-generation restorative materials through a bottom-up approach to understanding their properties.
Proceedings Title
Dental Materials 2: Polymer-Based Materials
Conference Dates
July 21-24, 2021
Conference Location
Boston, MA, US
Conference Title
IADR/AADR/CADR General Session


structure-property, biocomposite, cellulose, fluorescence microscopy, self-assembly


Easter, Q. , Chen, S. , Woodcock, J. , Souna, A. , Seethamraju, S. , Obrzut, J. , Fox, D. , Stranick, S. and Gilman, J. (2021), Fluorescence Microscopy Reveals Structure-Property Relationships and Polymer Dynamics in Biocomposites, Dental Materials 2: Polymer-Based Materials, Boston, MA, US, [online], (Accessed May 26, 2024)


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Created July 21, 2021, Updated March 13, 2023