Thermotropic Liquid Crystalline Polymers with Various Alkoxy Side Groups: Thermal Properties and Molecular Dynamics

Abstract

Two series of thermotropic liquid-crystalline polymers (TLCPs) were synthesized by reacting various dialkoxy terephthalate units with hydroquinone (HQ) and 2,6-naphthalene diol (Naph). The dialkoxy terephthalate moieties used in this study include 2,5-diethoxyterephthalate, 2,5-dibutoxyterephthalate, and 2,5-dihexyloxy-terephthalate. All the TLCPs synthesized in this study formed nematic phases. The molecular motions according to the length of the dialkoxy side groups in the TLCPs were evaluated by 13C cross-polarization/magic angle spinning nuclear magnetic resonance spectroscopy. The thermal properties and molecular dynamics of the TLCPs are found to be affected by the length of the dialkoxy side group and the aromatic diol unit in the main chain. Further, the thermal behaviors, liquid crystalline mesophases, and degree of crystallinity of the two series of TLCPs, i.e., HQ- and Naph-TLCPs, are compared.

Synthesis and characterization of poly(phthalazinone ether ketone ketone) copolymers with 4,4′-dihydroxybiphenyls

“…0.1 gram of meta-PPBEKK was put in 1 mL solvent and continuously stirred at room temperature for 24 hours. The solvent H 23 was a mixture (1,1′,2,2′,-tetrachloroethane/p-chlorophenol = 1/1, volume/volume). The results are shown in Table 2.…”

3D printing in materials manufacturing industry: A realm of Industry 4.0

“… SGC A photopolymer-based AM technology creates the layer geometry by passing a laser source [56] , [57] . LTP Similar to SL, this method builds the part using thermal energy to solidify successive layers of liquid thermosetting polymer [58] , [59] . BIS A point-by-point photosensitive polymer solidification at the intersection of two different wavelength laser beams [33] , [60] .…”

Effects of Para‐ or Meta‐Aromatic Amide Units on the Microstructure, Thermal, Mechanical, Rheological, and Dielectric Properties of Thermotropic Liquid Crystalline Poly(ester amide)s

“…[ 1–10 ] TLCPs form partially ordered and anisotropic liquid crystals even above their melting transition temperatures due to rigid rod‐shaped structural units called mesogenic units. [ 6,11–16 ] Accordingly, TLCPs are applied to super‐engineering thermoplastics, technical fibers, composite materials for automobile parts, etc. In addition, they are considered printed circuit board (PCB) and antenna materials for next‐generation communication due to their inherent characteristics of low dielectric constant and hygroscopicity.…”