Preparation of optical waveplates from cellulose nanocrystal nematics on patterned polydimethylsiloxane substrates

Optical waveplates play an essential role in controlling polarization in various applications. We show the feasibility of facile production of optical waveplates from plant-based cellulose nanocrystal (CNC) nematics. We align CNC nematic liquid crystals doped with polyethylene glycol on periodically patterned polydimethylsiloxane substrates on large scale by shearing forces and prepare a 1/4 λ and a 1/2 λ CNC waveplates for 530 nm by bonding two slices of CNC nematic films with half-period displacement. The optical performance of the CNC waveplates is investigated by Mueller matrix analysis and is examined by measuring the transmission spectra of the waveplate between two polarizers, and optical extinction and birefringence of CNCs are extracted from the measured spectra. Our CNC waveplates of arbitrary phase difference are flexible and can be tailored into any desirable shape conveniently.