New thermochromic liquid–crystalline polymer: Synthesis and phase behavior

Abstract

A series of new thermochromic side-chain liquid-crystalline polymers were prepared. The chemical structures of the resulting monomers and polymers were characterized by element analyses, FTIR, 1 H-NMR, and 13 C-NMR. Their mesogenic properties were investigated by differential scanning calorimetry, thermogravimetric analyses, polarizing optical microscopy, and X-ray diffraction measurements. The influence of the content of dye groups on phase behavior of the polymers was discussed. The polymers P 1 -P 3 showed smectic phase, and P 4 -P 7 revealed cholesteric phase. The polymers containing less than 30 mol % of the dye groups showed good solubility, reversible phase transition, wider mesophase temperature ranges, and higher thermal stability. Experimental results demonstrated that the clearing temperature and mesophase temperature ranges decreased with increasing the concentration of the dye groups.

Synthesis and characterization of polycholesteryl methacrylate–polyhydroxyethyl methyacrylate block copolymers

“…The T g of PCMA was determined to be 82–94 °C, which is consistent with T g of polyacrylates. However, T c is expected to be higher than the decomposition temperature of these polymers 36, 37, 39. As we mentioned, a 5–8% weight loss took place below 100 °C for both precursor copolymers and product copolymers, which made it difficult to determine both the T g and T c of the precursor and the product diblock copolymers.…”

“…Zhang and coworkers prepared a library of copolymers by linking cholesterol and other side groups via different spacers onto polysiloxanes backbone. The influence of the side groups (other than cholesterol) on LC order has been studied 12, 25–36. In another example, Mallia and coworkers synthesized a series of glassy LC oligomers containing cholesterol mesogens; hydrogen bonding dopants or nanoparticles were added to these polymers and their influence on LC and thermooptical properties were analyzed 37–46.…”

Polymers Comprising Cholesterol: Synthesis, Self-Assembly, and Applications

“…Efforts to combine cholesterol monomers with various other mesogenic and non-mesogenic groups, chiral and achiral groups, dopants, and cross-linkers are examined. A wide variety of investigation based on methods, composition, mesophase morphology, and thermal properties of copolymers comprising cholesterol are reported [ 34 , 38 , 41 , 42 , 49 , 50 , 66 , 67 , 68 , 69 , 70 , 71 , 72 ]. Flexible cross-linkers, non-mesogenic, chiral, and photochromic groups have been used in efforts to push the commonly observed smectic LC phase to the less-ordered cholesteric phase ( Table 3 ).…”

Side-chain Liquid Crystal Polymers (SCLCP): Methods and Materials. An Overview

“…Wide temperature ranges of SmC phase place them as potentially useful photochromic materials. [ 70 ]…”