Straightforward Access to Block and Gradient Light‐Responsive Poly(2‐Oxazoline)S via Cationic Ring Opening Polymerization Of 2‐Azobenzenyl‐2‐Oxazoline

Abstract

Light‐responsive polymers are a prospective area of smart materials. The increasing number of potential applications of these materials require the development of new polymers sensitive to external irradiation. However, most of the polymers reported so far are represented by poly(meth)acrylates. In this work, the straightforward approach is proposed to the synthesis of light‐responsive poly(2‐oxazoline)s via cationic ring‐opening polymerization of 2‐azobenzenyl‐2‐oxazoline (2‐(4‐(phenyldiazenyl)phenyl)‐2‐oxazoline). Polymerization kinetics studies reveal significant activity of the new monomer in both homopolymerization and copolymerization with 2‐ethyl‐2‐oxazoline. The difference in monomer reactivity allows obtaining both gradient and block copolymers via simultaneous or subsequent one‐pot polymerization, respectively, leading to a set of well‐defined gradient and block copoly(2‐oxazoline)s with 10–40% of azobenzene units. Due to their amphiphilic nature, the materials self‐assemble in water, which is proven by dynamic light scattering and transmission electron microscopy. The change in polarity caused by the isomerization of azobenzene fragments in response to UV light irradiation results in a change of nanoparticle size. The obtained results provide a new impulse for the development of light‐responsive materials based on poly(2‐oxazoline)s.

Substrate Channeling in Compartmentalized Nanoreactors

“…Amphiphilic block copolymers which self-assemble in solution can form micellar structures with channels. ,,, When polymers are functionalized with responsive units, such as photoswitchable spiropyran, polymeric micelle-supported catalytic systems can change their activity and selectivity, opening and closing channels in response to external stimuli. − Shell cross-linked micelles (SCMs), in particular, have the potential to functionalize multiple domains. ,, SCMs, composed of a hydrophobic core, a hydrophilic corona, and a cross-linked shell, can be used as nanoreactors for reactions under sustainable conditions ( e.g. , water as the only solvent).…”