Multimodal stimuli-responsive behaviors of photochromic spiropyran-bearing telechelic poly(2-isopropyl-2-oxazoline)

Antifouling polymers for nanomedicine and surfaces: recent advances

“…Another class of polymers that has been extensively studied as PEG replacements in nanomedicine applications are the poly (2-oxazoline)s. [45][46][47][48][49][50][51][52][53] First discovered over 50 years ago, these synthetic polymers bear resemblance to polypeptides in terms of their structure and properties. As with PEG, poly(2-oxazoline)s are strongly hydrophilic polymers that are antifouling, biocompatible, and non-immunogenic.…”

A Paper‐Like Hydrogel for Versatile Information Encryption and Decryption Via Chemical‐Induced Phase Separation

“…The underlying mechanism is either the adjustment of chemical color, which is determined by the chemical structure of the chromophore involved, or the adjustment of physical color, which depends on the microstructure or is related to the physical properties such as transmission, refraction, scattering, and interference/diffraction. [20] Although hydrogel-based information storage using chemical color is highly designable and can be achieved by means of a wide range of stimuli, such as light, [21] electricity, [22] heat, [23] pH, [24] and lanthanide ions or other chemicals, [12,[25][26][27][28] it generally demands a specific material design and synthesis by incorporating responsive species (e.g., chromophores) that usually react to a single stimulus, limiting the versatility. As for hydrogel information storage based on physical color, most studies use polymers that undergo thermally induced phase separation on heating (LCST) or cooling (with an upper critical solution temperature: UCST), including PNIPAM, [29] poly(2-isopropyl-2oxazoline), [21] poly(acrylamide-co-acrylonitrile) [30] and polyacrylamide (PAAm), [31] to realize optical transmittance change.…”

“…[20] Although hydrogel-based information storage using chemical color is highly designable and can be achieved by means of a wide range of stimuli, such as light, [21] electricity, [22] heat, [23] pH, [24] and lanthanide ions or other chemicals, [12,[25][26][27][28] it generally demands a specific material design and synthesis by incorporating responsive species (e.g., chromophores) that usually react to a single stimulus, limiting the versatility. As for hydrogel information storage based on physical color, most studies use polymers that undergo thermally induced phase separation on heating (LCST) or cooling (with an upper critical solution temperature: UCST), including PNIPAM, [29] poly(2-isopropyl-2oxazoline), [21] poly(acrylamide-co-acrylonitrile) [30] and polyacrylamide (PAAm), [31] to realize optical transmittance change. Thermally responsive hydrogels are easy to prepare, with temperature as the primary stimulus for the physical color adjustment.…”

“…[29,[32][33][34] By contrast, there are few studies on phase separation caused by chemical stimulation. The hydrogels are often activated by a single chemical, such as DMSO, [17] ethanol, [18,31,35] NaCl, [36] ammonium sulfate, [37] and CO 2 , [21] and most of them are used for transient information storage. Therefore, it remains a great challenge to develop hydrogels for multiple modes of information storage based on physical color change from the phase separation induced by multiple chemicals or a large class of chemicals.…”

Spiropyran-based chromic hydrogels for CO2 absorption and detection

“…To date the use of SPs for optical CO 2 detection has been scarce and mainly circumscribed to liquid solutions and suspensions. On the one hand, the well-known interaction between carbon dioxide and amidines in protic solvents has been used to induce color changes in SPs upon CO 2 exposure in solution, either by incorporating amidine groups to their structure ( Darwish et al, 2011 ) or as external additives ( Darwish et al, 2010 ; Boyd et al, 2013 ; Shin et al, 2022 ). In a different approach, a mechanochromic SP was anchored in polyacrylate nanoparticles with pending amino groups, which swelled and changed their color when treated with CO 2 in liquid suspension ( Li et al, 2016 ).…”