Molecular Crystals and Liquid Crystals, Vol.680, No.1, 31-45, 2019
Synthesis and self-assembling of diblock copolymers containing a side-on liquid crystalline block and a pseudo-stilbene azobenzene block
Liquid crystalline (LC) diblock copolymers containing a side-on LC block and a pseudo-stilbene azobenzene block were synthesized, and their self-assembling in water/tetrahydrofuran (THF) was investigated. Side-on LC monomer 4''-methylacryloyloxybutyl 2,5-di(4'-butyloxybenzoyloxy) benzoate (4-MDBB) was synthesized, and then polymerized into P4MDBB through reversible addition-fragmentation chain transfer (RAFT) polymerization. A pseudo-stilbene azobenzene monomer 6-(N-methyl-N-(4-(4'-cyanophenylazo)phenyl)amino)hexyl methacrylate (6-NCN) was also synthesized. The diblock copolymers P4MDBB(m)-b-P6NCN(n) were obtained through the RAFT polymerization of 6-NCN by using P4MDBB as the chain transfer agent. The copolymers and the intermediates were confirmed by H-1 and C-13 NMR spectra, FT-IR spectra, UV-Vis spectra, mass spectra, DSC analysis, POM observations, GPC tests and contact angle measurements. The diblock copolymers self-assembled upon adding water slowly into their THF solutions. The self-assembling and the corresponding assemblies were characterized by fluorescence spectra, laser light scattering experiments as well as TEM measurements. Results demonstrated that these diblock copolymers form spherical aggregates in water/THF, but the aggregates are un-stretchable upon irradiation with polarized light.