Liquid crystalline (LC) triblock copolymers were used either as (i) a nematic matrix, which can be loaded with 10 wt% of CdSe/ZnS QDs, or (ii) a compatibilizer, which allows more than 1 wt% of QDs to be introduced in low-molecular-weight cholesteric LCs.

For the first time symmetrical photosensitive fully liquid crystalline side chain triblock copolymers (pAzo-b-pPhM-b-pAzo) and random copolymer (pAzo-ran-pPhM) with nematogenic phenyl benzoate (PhM) and photosensitive smectogenic azobenzene containing groups (Azo) were synthesized by combination of RAFT polymerization and subsequent chemical modification. The central block of synthesized photochromic block copolymers contains 80 PhM groups, while the length of "peripheral" blocks includes 4 or 10 Azo units. The microphase separation structure is observed in block copolymer when the length of subblock with Azo groups reaches ten monomeric units. The influence of photochromic polymers molecular architecture (homopolymer, block copolymer and random copolymer) on the photochemical and photoorientation processes induced by light in their amorphous films have been revealed. The optical anisotropy induced in block copolymer films by illumination with linearly polarized 546 nm light was studied and the results compared with those of the Azo homopolymer and of a random copolymer with a similar composition. It was found that practically only Azo groups are included in the process of photoinduced orientation in films of block copolymer, whereas the orientational cooperative effect of both azobenzene chromophore and phenyl benzoate mesogenic groups is observed in the case of random copolymer.

Using liquid crystalline triblock copolymer complexes with hydrogen-bonded azobenzene moieties, photopatterned colorless birefringent films were prepared by irradiation with linearly polarized light and subsequent extracting azobenzene moieties.

surface relief gratings, liquid crystalline (LC) polymers are suitable for a polarization grating recording due to their high optical birefringence and cooperativity at the molecular level. [15] The majority of recent reports on this kind of materials concern LC homopolymers, random copolymers, and block copolymers that contain azobenzene and amorphous blocks. In block copolymers, the formation of an LC phase competes with the nanoscale segregation of constituent blocks. It yields synergy of various nanostructures such as spheres, cylinders and lamella, and properties of an LC phase (a cooperative molecular motion and high anisotropy of physical parameters). [16,17] In addition, due to the formation of a microphase-separated structure, the local concentration of azobenzene groups in block copolymer films is as high as in azobenzene homopolymers. It can provide considerable faster recording and higher efficiency in comparison with random copolymers. [18] To date the holographic recording in LC block copolymers containing azobenzene and amorphous blocks has been studied extensively. [17][18][19][20][21][22] Amorphous blocks of such block copolymers do not contribute to the optical response and do not participate in the holographic recording. On the other hand, introducing LC (mesogenic) groups in each block of block copolymers assures controlling optical properties of every microphase. [23] The presence of mesogenic groups in each block may bring into a play the whole polymer volume, thus increasing efficiency of these materials from the standpoint of the holographic recording. However, there is only one short mention concerning the holographic recording in films of azobenzene LC diblock copolymers comprised of only mesogenic monomer units. [24] Although fully LC block copolymers are envisioned as novel efficient materials for the holographic recording, such copolymers are far from being elucidated properly.In our previous work, we have synthesized LC photo sensitive ABA triblock copolymers comprised of azobenzene (Azo) and non-photosensitive phenyl benzoate (PhM) units. [23] We have also demonstrated that the irradiation of these materials with linearly polarized light and subsequent annealing offer an efficient tool for the selective control over the orientation of Azo and PhM groups. [25] In this communication, we aim to study holographic behavior of fully LC ABA triblock copolymer (Block) composed of Azo and PhM mesogenic units (Figure 1a) with the focus on polarization holographic gratings. As reference samples, Photosensitive liquid crystalline (LC) block copolymers are a universal platform for designing functional materials for optics and photonics. Here, azobenzene LC ABA triblock copolymer containing mesogenic groups in each block is studied as a medium for the recording of polarization holographic gratings. The fast recording of polarization gratings is successfully performed with two orthogonally circularly polarized light beams of a 532-nm laser. It is shown that annealing of the recorded polarization g...