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

Abstract

Using alternating diene metathesis (ALTMET) polycondensation and acyclic diene metathesis (ADMET) polymerization, two kinds of alternating and random copolymers from electron-deficient azobenzene (azo)-functionalized α,ω-diene monomers that are photoresponsive molecules and comonomers such as electron-rich carbazole or fluorene-functionalized diene or diacrylate monomers were synthesized. All of these copolymers were tailored to explore the effects of alternating and random monomer sequences and electron transfer capability on the self-assembly morphology and photoresponsive properties. As expected, the distinct absorption features from azo units in these copolymers are observed in their optical spectra, which cannot be achieved by traditional azo-containing homo- and copolymers. Because of the presence of stiff and electron-rich carbazole or fluorene motifs, the ability and efficiency of photoisomerization was depressed to some extent according to the sequential differences of two monomers and the electron effect in the copolymer chain. Moreover, the sizes and morphologies of alternating copolymers can be modulated through the methylene spacer and sequence of rigid conjugated motifs generating diverse nanostructures leading to a different chain mobility, which ultimately exhibited the unique photoisomerization behaviors. These interesting findings not only demonstrate a facile and efficient method for constructing azo-carbazole and azo-fluorene metathesis copolymers but also expand the optical properties of azo-containing polymers.

Photocontrol of pattern formation and hysteresis loops in polymer gels with host-guest interactions

“…These values are chosen within the range for the photoisomerization and thermal relaxation of azobenzene derivatives incorporated into the polymers, specifically within the range of for and (Ref. 73 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 ), and for (Ref. 18 , 82 , 83 , 84 , 85 , 86 ).…”

Reversibly photoswitchable catalysts for high regioselectivity and enantioselectivity in polymerization of allenes

“…Due to the obvious difference between the apparent polymerization rate coefficients of D-2 and L-2 under dark conditions, an enantioselective polymerization of a racemic mixture of D-2 and L-2 initiated by Ni(II)/L R-azo was attempted, as shown in Scheme 3. Then the polymerization of the racemic solution mixture of D-2 and L-2 proceeded using chiral Ni(II)/ L R-azo as initiator under dark conditions at 35 L-2) 100 (L R-azo ) at maximum absorption of 260 nm was calculated as 5.0 M −1 cm −1 until the monomer was not consumed. Compared to the CD value of poly-D-2 100 (L R-azo ) of 8.3 M −1 cm −1 polymerized from D-2, the CD value of isolated poly-(D-2 + L-2) 100 (L R-azo ) had decreased a little (Fig.…”

“…[30][31][32] Both of its isomers have distinct spectral and geometric properties, which make it an ideal model system to be used in the field of molecular transducers in light-driven equipment and optical switches. [33][34][35] Chen and coworkers reported the photoswitchable properties of salicylaldimine Zn (II) complexes containing an azobenzene unit during the catalysis of the ring-opening polymerization of a series of cyclic ester-type monomers. 36 Photoinduced RAFT polymerization with the help of photosensitive azobenzenes has also been reported in the past.…”

Anti-Ultraviolet Biobased Polyesters Synthesized by Acyclic Diene Metathesis Polymerization

“…Melt polycondensation is a commonly used method in the preparation of polyesters, but it may lead to thermal degradation of polyesters under high temperature and vacuum conditions . Ring-opening polymerization (ROP) is a frequently used alternative route, but lactone monomers are not easily obtained. , Acyclic diene metathesis (ADMET) polymerization is gradually considered as a practical technology in the field of biobased polyesters. − Compared to ROP, ADMET polymerization is capable of applying to a wider range of polymer compositions and structures . It has the advantages of high tolerance to many functional groups, mild polymerization conditions, and efficient conversion of double bonds .…”