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Contains fulltext : 298319.pdf (Publisher’s version ) (Closed access), 31 oktober 2022

Micro-capillaries, capable of light-regulated binding and qualitative detection of divalent metal ions in continuous flow, have been realised through functionalisation with spiropyran photochromic brush-type coatings. Upon irradiation with UV light, the coating switches from the passive non-binding spiropyran form to the active merocyanine form, which binds different divalent metal ions (Zn2+, Co2+, Cu2+, Ni2+, Cd2+), as they pass through the micro-capillary. Furthermore, the merocyanine visible absorbance spectrum changes upon metal ion binding, enabling the ion uptake to be detected optically. Irradiation with white light causes reversion of the merocyanine to the passive spiropyran form, with simultaneous release of the bound metal ion from the micro-capillary coating.

Micro-capillaries, capable of light-regulated binding and qualitative detection of divalent metal ions in continuous flow, have been realised through functionalisation with spiropyran photochromic brush-type coatings. Upon irradiation with UV light, the coating switches from the passive non-binding spiropyran form to the active merocyanine form, which binds different divalent metal ions (Zn2+, Co2+, Cu2+, Ni2+, Cd2+), as they pass through the micro-capillary. Furthermore, the merocyanine visible absorbance spectrum changes upon metal ion binding, enabling the ion uptake to be detected optically. Irradiation with white light causes reversion of the merocyanine to the passive spiropyran form, with simultaneous release of the bound metal ion from the micro-capillary coating.

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.

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.

Micro-capillaries, capable of light-regulated binding and qualitative detection of divalent metal ions in continuous flow, have been realised through functionalisation with spiropyran photochromic brush-type coatings. Upon irradiation with UV light, the coating switches from the passive non-binding spiropyran form to the active merocyanine form, which binds different divalent metal ions (Zn2+, Co2+, Cu2+, Ni2+, Cd2+), as they pass through the micro-capillary. Furthermore, the merocyanine visible absorbance spectrum changes upon metal ion binding, enabling the ion uptake to be detected optically. Irradiation with white light causes reversion of the merocyanine to the passive spiropyran form, with simultaneous release of the bound metal ion from the micro-capillary coating.

A great number of stimuli-responsive materials have been reported in the recent years and they find applicability in fields ranging from optoelectronics, surface coatings, photonics and biomedicine. A particular attractive class of stimuli-responsive materials is comprised by photo-responsive materials as light is an environment-friendly stimulus and can be applied remotely, in a non-invasive manner. Photo-responsive materials have been the subject of many investigations over the past decade due to their potential applications, particularly in the design and development of memory devices, artificial muscles, soft-actuators and drug delivery, among others[1]. In the field of photo-responsive polymers, the layer-by-layer (LbL) approach offers a simple and effective method to fabricate uniform thin films capable of photo-modulation. In this context, we are focusing our investigations on the synthesis of LbL coatings based on new photochromic norbornenes polymers bearing spiropyran side groups. We have shown that these LbL coatings are capable of disassembling upon photostimulation. When used for the coating of microcapsules, these polymers have the ability to be used for photo-controlled drug delivery. [1] L. Florea, D. Diamond, F. Benito-Lopez, Macromol. Mater. Eng. 2012, 297, 1148.

A great number of stimuli-responsive materials have been reported in the recent years and they find applicability in fields ranging from optoelectronics, surface coatings, photonics and biomedicine. A particular attractive class of stimuli-responsive materials is comprised by photo-responsive materials as light is an environment-friendly stimulus and can be applied remotely, in a non-invasive manner. Photo-responsive materials have been the subject of many investigations over the past decade due to their potential applications, particularly in the design and development of memory devices, artificial muscles, soft-actuators and drug delivery, among others[1]. In the field of photo-responsive polymers, the layer-by-layer (LbL) approach offers a simple and effective method to fabricate uniform thin films capable of photo-modulation. In this context, we are focusing our investigations on the synthesis of LbL coatings based on new photochromic norbornenes polymers bearing spiropyran side groups. We have shown that these LbL coatings are capable of disassembling upon photostimulation. When used for the coating of microcapsules, these polymers have the ability to be used for photo-controlled drug delivery. [1] L. Florea, D. Diamond, F. Benito-Lopez, Macromol. Mater. Eng. 2012, 297, 1148.

A great number of stimuli-responsive materials have been reported in the recent years and they find applicability in fields ranging from optoelectronics, surface coatings, photonics and biomedicine. A particular attractive class of stimuli-responsive materials is comprised by photo-responsive materials as light is an environment-friendly stimulus and can be applied remotely, in a non-invasive manner. Photo-responsive materials have been the subject of many investigations over the past decade due to their potential applications, particularly in the design and development of memory devices, artificial muscles, soft-actuators and drug delivery, among others[1]. In the field of photo-responsive polymers, the layer-by-layer (LbL) approach offers a simple and effective method to fabricate uniform thin films capable of photo-modulation. In this context, we are focusing our investigations on the synthesis of LbL coatings based on new photochromic norbornenes polymers bearing spiropyran side groups. We have shown that these LbL coatings are capable of disassembling upon photostimulation. When used for the coating of microcapsules, these polymers have the ability to be used for photo-controlled drug delivery. [1] L. Florea, D. Diamond, F. Benito-Lopez, Macromol. Mater. Eng. 2012, 297, 1148.