Photoswitchable Layer-by-layer Coatings Based on Photochromic Polynorbornenes Bearing Spiropyran Side Groups
- Authors:
- P. P. Campos, A. Dunne, C. Delaney, C. Moloney, S. Moulton, F. Benito-Lopez, M. Ferreira, D. Diamond, L. Florea
- Year:
- 2018
- Journal:
- Langmuir (IF: 3.833, 2017, Q1)
- Volume:
- 34
- Initial page - Ending page:
- 4210 - 4216
- ISBN/ISSN:
- 0743-7463
- Description:
-
Herein, we present the synthesis of linear photochromic norbornene polymers bearing spiropyran side groups (poly(SP-R)), and their assembly into LbL films on glass substrates when converted to the poly(MC-R) under UV irradiation. The LbL films were composed of bilayers of poly(allylamine hydrochloride) (PAH) and poly(MC-R), forming (PAH/poly(MC-R))n coatings. The MC form presents a significant absorption band in the visible spectral region which allowed the LbL deposition process to be tracked by UV-Vis spectroscopy, showing a linear increase of the characteristic MC absorbance band with increased number of bilayers. The thickness and morphology of the (PAH/poly(MC-R))n films were characterised by ellipsometry and Scanning Electron Microscopy, showing a height of ~27.5 nm for the first bilayer and an overall height of ~165 nm for the (PAH/poly(MC-R))5 multilayer film. Prolonged white light irradiation (22h) showed a gradual decrease of the MC band by 90.4 ±2.9% relative to the baseline, indicating the potential application of these films as coatings for photo-controlled delivery systems.