Topological Transition in Spontaneously Formed Cellulosic Liquid-Crystalline Microspheres in a w/o Emulsion.

A cholesteric liquid crystal (ChLC) in a confined space has attracted significant scientific interest and has potential applications. ChLC microspheres have been obtained by devising processing such as a microfluidic technique. Herein, we adopted the self-assembly approach for the spontaneous formation of cellulosic ChLC microspheres. A functional block copolymer (BCP) was grafted to hydroxypropyl cellulose (HPC), making it amphiphilic to self-assembly in a w/o emulsion. The HPC segment aggregated in the aqueous phase under lyotropic conditions and produced the ChLC microspheres dispersed in the oil phase. The microspheres exhibited a topological transition between radial and bipolar while altering the molecular structure in terms of the molecular weight of BCP and the degree of substitution of HPC. The coexistence of inorganic salts in the aqueous HPC lyotropic phase changed the mesophase behavior as well. Such cellulosic ChLC microspheres will present opportunities to develop biobased optical devices and stimuli responsive biomedical materials.