Abstract
Structurally-colored cholesteric cellulose ether materials offer a sustainable alternative to traditionally-dyed plastics. These materials are produced by dissolving high concentrations of cellulosic polymers in a monomeric solvent, forming a liquid crystalline mesophase, and polymerizing to kinetically trap the ordered arrangement in a composite. Despite significant advancements in fabricating colorimetric films and devices using this method, the lack of critical design rules for predicting color evolution upon polymerization hinders large-scale deployment and rational design. In this work, ethyl cellulose-poly(acrylic acid) films are used as a model system to explore how the balance between polymer chain mobility and solvent photopolymerization kinetics affect the preservation of cholesteric texture and optical properties. These findings reveal that the observed blue-shift in reflectivity is linked to the realignment or disruption of chiral nematic order during poly(acrylic acid) chain growth. Time-resolved studies during UV curing, including in situ reflection spectroscopy and rheometry, demonstrate that rapid polymerization and reduced polysaccharide mobility are key to maintaining the color and angle-dependent optical appearance in the final films. Applying these fundamental design principles, we create composites with spatially-controlled photopatterned colors, tailored angle-resolved reflectivity that resists photobleaching, and reversible colorimetric functions that are unattainable with pigmented plastics.
| Original language | English (US) |
|---|---|
| Article number | 2500521 |
| Journal | Advanced Optical Materials |
| Volume | 13 |
| Issue number | 19 |
| DOIs | |
| State | Published - Jul 4 2025 |
| Externally published | Yes |
Funding
The authors thank Eric C. Abenojar and Prof. Julia A. Kalow for their assistance with GPC measurements, Sumit Kewalramani for his help with X-ray studies, Carla Shute for her aid with rheometry, and the members of the Sustainable Polymer Innovation (SPIn) Lab for their continued support. This work was primarily supported by a seed grant from the Paula M. Trienens Institute for Energy and Sustainability at Northwestern University, supporting S.G.F. and research expenses. S.G.F. also gratefully acknowledges support from the Ryan Fellowship and the International Institute for Nanotechnology (IIN) at Northwestern University. C. G. was primarily supported through the Meister research-as-work-study program in the Department of Materials Science and Engineering at Northwestern University. This work made use of the MatCI Facility supported by the MRSEC program of the National Science Foundation (DMR-2308691) at the Materials Research Center of Northwestern University. This work made use of the Jerome B. Cohen X-Ray Diffraction Facility supported by the MRSEC program of the National Science Foundation (DMR-2308691) at the Materials Research Center of Northwestern University and the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205.). This work made use of the Keck Biophysics Facility's Azure Sapphire Imager funded by the 1S10OD026963-01 NIH grant. This work made use of the SPID facility of Northwestern University's NUANCE Center, which has received support from the SHyNE Resource (NSF ECCS-2025633), the IIN, and Northwestern's MRSEC program (NSF DMR-2308691). The authors thank Eric C. Abenojar and Prof. Julia A. Kalow for their assistance with GPC measurements, Sumit Kewalramani for his help with X‐ray studies, Carla Shute for her aid with rheometry, and the members of the Sustainable Polymer Innovation (SPIn) Lab for their continued support. This work was primarily supported by a seed grant from the Paula M. Trienens Institute for Energy and Sustainability at Northwestern University, supporting S.G.F. and research expenses. S.G.F. also gratefully acknowledges support from the Ryan Fellowship and the International Institute for Nanotechnology (IIN) at Northwestern University. C. G. was primarily supported through the Meister research‐as‐work‐study program in the Department of Materials Science and Engineering at Northwestern University. This work made use of the MatCI Facility supported by the MRSEC program of the National Science Foundation (DMR‐2308691) at the Materials Research Center of Northwestern University. This work made use of the Jerome B. Cohen X‐Ray Diffraction Facility supported by the MRSEC program of the National Science Foundation (DMR‐2308691) at the Materials Research Center of Northwestern University and the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS‐1542205.). This work made use of the Keck Biophysics Facility's Azure Sapphire Imager funded by the 1S10OD026963‐01 NIH grant. This work made use of the SPID facility of Northwestern University's NUANCE Center, which has received support from the SHyNE Resource (NSF ECCS‐2025633), the IIN, and Northwestern's MRSEC program (NSF DMR‐2308691).
Keywords
- cellulose
- cholesteric liquid crystal
- photopolymerization
- reflection spectroscopy
- structural color
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics