Azobenzene‐Incorporated Single‐ and Double‐Stranded Polynorbornenes: Facile Synthesis and Diverse Photoresponsive Property

Abstract

Double‐stranded polymeric ladderphane using azobenzene as linkers and the single‐stranded polynorbornene with azobenzene pendants are synthesized by the ring‐opening metathesis polymerization using Grubbs ruthenium‐based catalyst. Hydrolysis of these as‐prepared polynorbornenes gives the corresponding isotactic single‐stranded polynorbornene having similar polydispersity and degree of polymerization as those of the original polymers. The photosensitive property of double‐stranded ladderphane indicates significant interactions between adjacent chromophores. These single‐ and double‐stranded polynorbornenes incorporating azobenzene chromophores exhibit distinct photoresponsive performance in the dilute solutions. The rate of photoisomerization for double‐stranded ladderphane is found to be from 6 to 9 times slower than that obtained for single‐stranded polymer. This is ascribed to the differences in structure of polymers and the interaction between azobenzene chromophores in the polymers.

Formation and characteristics of starch‐based dual photo‐function composite hydrogel

“…Because the azobenzene‐based trans‐isomer can be converted to the cis‐one upon UV light irradiation and return to the trans‐isomer by visible light irradiation or in dark storage, azobenzene units are often used as the light‐responsive group. Such a strategy is widely employed to make polymer photo‐switchable . We also have adopted this method to prepare starch‐based pH‐responsive and light‐responsive hydrogel.…”

“…Such a strategy is widely employed to make polymer photo-switchable. 17,18 We also have adopted this method to prepare starch-based pH-responsive and light-responsive hydrogel. Herein, another component to act photofunction is introduced.…”

Azobenzene-containing Alternating and Random Metathesis Copolymers toward Gaining More Insight into Photoisomerization Properties

“…It is feasible to expect that the nonconjugated structure can also endow azo-polymers with decreased photoisomerization efficiency and capability. Actually, the nonconjugated azo-polymers indeed undergo a photoisomerization depressing phenomenon based on the specific location and sequence of azo units . Therefore, it is necessary to find a versatile and efficient solution for constructing azo-polymers with special structures and primarily investigate the actual reasons for weakening the photoisomerization behavior.…”

ROMP of supramolecular norbornene monomers containing β-cyclodextrin–ferrocene (/adamantane) inclusion complexes

“…Thus, using this technique, various well-defined homopolymers and copolymers, whose polydispersity indexes (PDIs) are normally less than 1.2, can be prepared for all kinds of functional applications, such as their use in drug delivery [7], bioimaging [8], and catalysis [9], along with their preparation as nanoparticles [10] and hydrogels [11]. Through the use of norbornene-based monomers, polynorbornenes with various types of configurations can be synthesized, such as brush polymers [12], dendronized polymers [13], branched polymers [14], star polymers [15], ladderphanes [16], and multicyclic polymers [17][18][19]. The extensive application of ROMP is attributed to the high group tolerance of Grubbs' catalyst [1,20].…”