Influence of Spacer Lengths on the Morphology of Biphenyl-Containing Liquid Crystalline Block Copolymer Nanoparticles via Polymerization-Induced Self-Assembly

Polymerization-induced self-assembly (PISA) combining liquid crystallization has been proved an effective approach to one-dimensional block copolymer (BCP) nanoparticles (NPs). However, the liquid crystalline (LC) monomer library for the PISA systems is desired to be expanded. Moreover, the influence of molecular structure of LC moieties on the self-assembled morphology needs to be investigated in detail. In this work, we proposed a new PISA formulation based on biphenyl mesogen-containing BCPs with different spacer lengths. The thermal property, dispersion polymerization kinetics, and morphological evolution of BCP NPs with different spacer lengths were systematically investigated. The results indicate that the spacer length plays an important role in the physical appearance, micromorphology, and internal molecular arrangement of the NPs. The longer spacer is conducive to LC ordering within NPs, which induced the formation of rigid nanowires/nanorods. Owing to the strong coupling effect between backbone and mesogen, the NPs exhibit no LC property and form self-supporting gels when the spacer is short. This work expands the scope of LC monomer for PISA and provides the experimental reference for the design of new PISA formulations combining LC ordering.