A facile synthetic route to novel thermotropic liquid crystalline polymers and characterization of their mesophases

Abstract

We have succeeded in preparing novel liquid crystalline polymers of low melting temperature by a melt reaction between diepoxy molecules and a primary monoamine (aniline).

Synthesis of novel thermotropic liquid crystalline polymers by a reactive extrusion process

“…Increasing the length of the exible spacer in the main chain reduces the rigidity of the polymer backbone by decreasing the proportion of the mesogen unit. 19 Thus PDEN3 has a lower T g than PDEN1 because of its so backbone, but has a higher T m due to the greater ordering of its alkyl groups. Both polymers, however, have a low melting temperature (175 C for PDEN1 and 194 C for PDEN3), so they can easily be processed in an extruder or injection molding machine.…”

“…PDEN3 has a lower molar mass than PDEN1 because the diffusivity of the LCE3 monomer is lower than that of the LCE1 monomer, as found in our previous study. 19 These large PDI values indicate that the molar mass distribution of the TLCPs are quite broad. In bulk polymerizations, the viscosity increases as the polymerization progresses, which interferes with the diffusion of the LCEs.…”

“…Since we used the same mesogenic units (LCE1 and LCE3) as before, their diffraction patterns are quite very similar. 19 LC chains typically produce diffraction peaks corresponding to a lateral-packing of 3-6Å. 1,23,24 The peaks in the wide angle region are broader than those of PDEA1 and PDEA3, which indicates that the ordering of the PDEN1 and PDEN3 chains is more liquid-like (less ordered) due to their bulkier side groups.…”

“…These brils protrude above the fractured surfaces, and are thus part of continuous bril morphologies on the TLCP surfaces that are oriented parallel to the bril direction. 13,19,27 Conclusions New liquid crystalline polymers with low melting temperatures have been successfully synthesized by performing polyaddition reactions between diepoxide molecules and a primary monoamine (1-naphthylamine). Although the polymers synthesized via the reactive extrusion process have lower molar masses than the same polymers prepared in bulk reactions due to their short reaction time in the extruder, this approach is commercially very signicant because of its potential for the mass production.…”

“…[19][20][21][22] We have previously reported a new and simple process for the preparation of a novel type of thermotropic liquid crystalline polymers via a polyaddition reaction. 19 This process consists of the reaction between a diepoxide compound with a primary monoamine (aniline) to produce a linear chain connecting the two epoxy groups. This approach can produce high molar mass TLCPs that have a low processing temperature because no by-products are generated that must be removed.…”