Synthesis and characterization of novel photoisomerizable liquid crystalline polymers containing cinnamoyl groups

Abstract

A series of novel liquid crystalline monomers and polymers incorporating phenylbenzoate or phenylcinnamate segments as mesogenic cores have been synthesized to investigate the sensitivity of the photochromic cinnamoyl derivatives and to overcome the defects of the thermal instability of azobenzene. Their liquid crystalline, thermal, and photoinduced properties of all monomers and polymers were characterized. The polymers showed excellent solubility in common organic solvents such as CHCl3, toluene, and DMF and exhibited good thermal stability with decomposition temperatures (Td) at 5% weight loss greater than 340 °C and about 50% weight loss occurred beyond 430 °C under nitrogen atmosphere. The pitch length (about 574 nm) of the synthesized cholesteric polymeric film (CP2) was estimated using scanning electron microscopy. These photochromic polymers exhibited strong UV–vis absorption maxima at about 264 or 320 nm. Moreover, photo induced configurational E/Z isomerization further changed the π‐electron conjugation systems leading to a decrease at the π‐π* transition and an increase in the range of 300 nm to 400 nm for photochromic copolymers. The thermal stability of the Z‐structural segment was confirmed by heating the polymer at 50 °C for over 5 h. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1289–1304, 2008

Novel UV-sensitive bis-chalcone derivatives: synthesis and photocrosslinking properties in solution and solid PMMA film

“…Among the photosensitive materials, the UV-sensitive polymers have been highlighted because of their excellent properties and wide applications in many fields. The technological Z applications of these photoactive materials are in the fields of lithography [7][8][9][10], liquid crystals [11][12][13][14], nonlinear optical materials [15][16][17][18], optical anisotropy [19][20][21], and UV curing process [22][23][24].…”

Synthesis and characterization of optically active liquid crystalline polyacrylates containing mesogenic phenylbenzoate groups

“…4-(6-Acryloyloxyhexyloxy) benzoic acid and 4-(6-acryloyloxy-undecyloxy) benzoic acid were synthesized following the processes reported in the literature [22]. (À)-Cholesteryl 4-hydroxybenzoate and (À)-menthyl 4-hydroxybenzoate were synthesized following the processes reported in our previous reports [17,20,21]. The obtained products were purified and then identified using FTIR, 1 H NMR, 13 C NMR and elemental analysis.…”

“…The following monomers and chiral dopants were synthesized according to the similar procedures described in our previous reports [15,[17][18][19][20][21] and the literature [22]. 4-(6-Acryloyloxyhexyloxy) benzoic acid and 4-(6-acryloyloxy-undecyloxy) benzoic acid were synthesized following the processes reported in the literature [22].…”

“…In a series of studies, chiral monomers and chiral dopants were synthesized and their uses in the induction of cholesteric liquid crystal phases were also studied [15][16][17][18][19][20][21]. In the studies, the photochromic function was designed with azobenzene derivatives.…”

Synthesis, photochemical properties, and self-assembly of diblock copolymer bearing azobenzene moieties

“…We also used the conventional radical polymerization method to synthesize photoisomerizable LC polymers (CP3-CP5) containing cinnamoyl groups by using 2,2 -azoisobutyronitrile (AIBN) as the initiator, and performed E-Z photo stationary states within 10-20 m of UV irradiation (λ irr = 300 nm). However, these LC polymers showed extremely little self-assembled aggregates in aqueous solution [38]. Based on the original investigations above, in this study, we employed a two-step RAFT polymerization technique to synthesize a macro-chain transfer agent, StO macro-CTA, and a novel azo block polymer, poly(StO 50 -b-Azo 7 ).…”