Poly(2‐isopropyl‐2‐oxazoline) Bearing a Spiropyran Side‐Chain: Synthesis and Evaluation of Photo and Temperature‐Responsive Properties

Abstract

Poly(2‐isopropyl‐2‐oxazoline)s with varied loading of the spiropyran side‐chain are synthesized, and their photochemical and thermosensitive properties are characterized in aqueous solution. The absorption spectrum of the sample aqueous solution (0.1 wt%) indicates that 7.8 mol% of the pendant groups are in the zwitterionic merocyanine form. The introduction of spiropyran groups causes a marked decrease in the cloud point of the aqueous solution even when the pendant groups contain the zwitterionic merocyanine form. The cloud point of the aqueous solution of the samples in the spiropyran form is slightly (less than 1 °C) lower than that bearing the merocyanine group. Moreover, the photoinduced phase transition is demonstrated at an optimum temperature for the spiropyran‐bearing poly(2‐isopropyl‐2‐oxazoline). This material can be made applicable to a light‐driven drug releasing system by introducing a hydrophobic group to form micelles and increasing the photoinduced change of the cloud point.

Reversible Photoswitching in Poly(2‐oxazoline) Nanoreactors

“…However,p oly(2-oxazoline)s allow for precise post-polymerizationm odifications with SP which is unprecedented in block copolymers.N otably,arecent publication supported SP on poly(2-isopropyl-2-oxazoline) homopolymers but required partial hydrolysis of the amide backbone. [36] In this contribution, we incorporate SP onto amphiphilic poly(2-oxazoline)s throughc lick chemistry and demonstrate the retention of the SP-MC isomerization upon UV-light irradiation. Ac ovalently attached base catalyzes aK noevenagel condensation with shifts in reactionr ates in response to changes in nanostructure morphologies.…”