Photoinduced Deadhesion of a Polymer Film Using a Photochromic Donor–Acceptor Stenhouse Adduct

Abstract

Photoisomerization of molecules dissolved in a polymer film can modulate its properties. In a previous paper (Mostafavi, S. H.;et al. Macromolecules 2018et al. Macromolecules , 51, 2388et al. Macromolecules −2394, it was found that the ultraviolet light-induced photoisomerization of spiropyran dopants could substantially increase adhesion to a glass surface. In this work, a different photochromic reaction, the visible-light-induced cyclization of a donor−acceptor Stenhouse adduct (DASA), leads to the opposite effect: the deadhesion of a polystyrene film from a clean glass surface. Measurements of the shear and pull-off adhesion strengths before and after visible irradiation show a light-induced decrease of 20−30%. The time required for delamination in water shows an even more dramatic decrease of 90%. Changes in the water contact angle and other measurements suggest that molecular-level noncovalent interactions between the polymer and glass are weakened after photoisomerization, possibly due to the molecular contraction of the DASA that disrupts the interaction between its amine groups and the surface silanols. The ability to reduce polymer adhesion using visible light enables the controlled release of dye molecules from a glass container, where these have been stored as a dry powder, into an aqueous solution. Embedding photochromic molecules in a polymer can lead to new effects that may have practical applications in stimuli-responsive materials.

Learning from Spiropyrans: How to Make Further Developments of Donor‐Acceptor Stenhouse Adducts

“…An extended system was realized by Read de Alaniz and co‐workers using DASAs as the photoresponsive molecules. [ 80 ] However, the linear ‐to‐ cyclic isomerization of DASAs led to an opposite effect, where the shear strength decreased by ~30% after visible light irradiation. This might be attributed to the weakened noncovalent interaction between the PS film and glass water.…”

Nano‐3D‐Printed Photochromic Micro‐Objects

“…Stimuli-responsive materials based on molecular photoswitches can reversibly change color and other photophysical properties from sensors to wavelength-specific photopatterning and visible light responsive enzyme nanoreactors. [16][17][18][19][20][21][22][23][24][25][26] In such multiaddressable materials, DASAs serve as molecular logic gates that only require different visible light sources to control the different states. [27,28] To date, however, DASAs have been studied mostly in 2D substrates such as polymer films and modified surfaces, which impedes the study of photochromism in defined 3D structures.…”

Light‐ and Chemical‐Stimuli‐Induced Isomerization of Donor−Acceptor Stenhouse Adducts

“…[13][14][15][16] They have been employed for a wide range of applications including drugdelivery, [17,18] chemical [19][20][21][22][23] and temperature [19,24] sensors, and surface chemistry. [25][26][27] Three generations have been developed upon tailoring the "donor" and "acceptor" moieties, showing tunable absorption wavelength, thermodynamic equilibria and solvent switching properties. [13,[28][29][30][31] The first generation contains secondary alkyl amine donors and either Meldrum's or barbituric acid acceptors.…”