Mesogen-jacketed liquid crystalline polymers via stable free radical polymerization

Abstract

SUMMARY: Stable free radical polymerization has been used in the controlled synthesis of poly (2,5-bis[(4-butylbenzoyl)oxy]styrene), PBBOS. This "mesogen-jacketed liquid crystalline polymer", which has mesogenic units attached directly to the backbone in a side-on mode, has been found to exhibit thermotropic liquid crystallinity similar to more conventional main-chain architectures. Stable free radical polymerization of PBBOS consistently produced molecular weight distributions below the theoretical limiting polydispersity of 1.5 calculated for a conventional free radical polymerization process. Surprisingly, a comparison of the synthesis of polystyrene to the polymerization of PBBOS under nearly identical conditions showed that the PBBOS polymerized with a significantly higher reaction rate and monomer conversion efficiency. The nematic phase of these polymers was determined to be stable over the temperature range spanning the polymer glass transition temperature up to the temperature for thermal decomposition. The molecular arrangement of the PBBOS polymers was examined by wide-angle X-ray diffraction and is described here.

Synthesis and Hierarchical Self-Assembly of Rod−Rod Block Copolymers via Click Chemistry between Mesogen-Jacketed Liquid Crystalline Polymers and Helical Polypeptides

“…The peak with q* at 3.97 nm -1 (corresponding to a d-spacing of 1.58 nm) could be attributed to the columnar nematic phase (Φ N ) of PMPCS, while the diffuse halo with q** at ∼13 nm -1 (corresponding to a d-spacing of about 0.48 nm) was attributed to the distances between mesogens, polymer backbones, and other parts of the BCP. 48 The 1D WAXD pattern of PMPCS 42 -b-PBLG 49 exhibited rather similar profile to that of PMPCS 42 -b-PBLG 19 for the Φ N phase of PMPCS with a d-spacing of 1.56 nm, and the reflection for PBLG was also found at 4.48 nm -1 with a d-spacing of 1.40 nm, which corresponded to a columnar diameter of 1.62 nm. The appearance of reflections from both PMPCS and PBLG indicated the microphase separation of the block copolymer.…”

Synthesis and Characterization of A New Series of “Mesogen-Jacketed Liquid Crystal Polymers” Based on the Newly Synthesized Vinylterephthalic Acid

“…The diffraction patterns were similar to those of other MJLCPs, 17,18 showing a diffused halo at larger angles and a relatively sharp peak at lower angles. According to Xu et al 18 and Ober et al, 13 the mesophase could be assigned to the nematic phase. However, this assignment is still not conclusive because there is no enough information about the relative orientational arrangement among the side groups.…”

Jacketed polymers: Controlled synthesis of mesogen‐jacketed polymers and block copolymers

“…Similar result was discovered by Ober and coworkers 35 in the synthesis of poly(2,5-bis[(4-butylbenzoyl)oxy]-styrene) (PBBOS).…”