Liquid Crystal Polymers (LCPs)

Liquid-crystal polymers (LCPs) are a class of aromatic polymers, which are extremely inert. They resist stress cracking in the presence of most chemicals at elevated temperatures including aromatic or halogenated hydrocarbons strong acids, bases, ketones, and other aggressive industrial substances Their hydrolytic stability in boiling water is excellent .

Described about classification, characterization and the properties of LCPs and their applications in different fields which have been initiated by its synthesis and characterization. Most LCP compounds show  polymorphism which was detected by various techniques like XRD, DSC and POM , introduced flexible technology and about the flexible fabricating antenna in which LCPs were the best substrate. Flexible antennas are robust and light weight, which withstand mechanical strain upto certain extent such as various HPP. As there is great demand of flexible electronics in various applications, it requires well suited material and LCP is significant material due to its mechanical and electrical properties. The antenna fabricated using LCP can be bent, twisted and rolled up. The antenna fabricated with LCP used for high performance microwave application.

Synthesized Novel thermotropic liquid crystal polymer (TLCP) which is synthesized by esterification and Polycondensation of Aromatic Compounds like 6- hydroxyl-2-naphthoic acid, 2,6-naphthlenedicarboxylic acid, 4- hydroxybenzoic acid or terephthalic acid. Aliphatic diols like ethyl glycol, 1,4-butadienol was used as flexible spacers to form semi-flexible main chain TLCP. Product were characterized by FTIR and 1 HNMR. Naphthalene decreased the melting temperature (Tm) of LCP (181-272 8C) to facilitate extrusion or injection molding, low Tm, etc. The novel LCPs exhibit improvements over Vectra in processability and cost.

Performed various kinds of experiments such as preparation of liquid crystalline prepolymer, distillates accompanying prepolymers, final polymers, and sublimates accompanying final polymers NaOD/D2O depolymerization of prepolymers and polymers back to monomers. Anhydride groups must render LCP’s more susceptible to degradation by nucleophilic reagents. His findings suggested that Fries rearrangement products detected in very small amounts accounted for yellowing in LCP’s. Both anhydrides and Fries rearrangements produce kinks in the polymer chains.

Prepared of LCP known as Vectra by acidolysis of 4-hydroxybenzoic acid with 6-hydroxy-2- napthalic acid. Kinetics of model reaction and of actual polycondensation followed second order kinetics and their rate constant. The mechanisms may include nucleophilic aromatic substitutions, chain polycondensation, esterolysis etc. Complication caused by ketene loss can be averted by the use of methoxycarbonyloxy monomers.

Prepared new, rigid-rod oligomers with LCrelated photoemission properties derived from aromatic structures in biomolecules available from microorganism. He synthesised functional bio-based polymers with LC properties, poly{3-benzylidene amino-4-hydroxybenzoic acid (3,4- BAHBA)-co-trans-4-hydroxycinnamic acid (4HCA: transcoumaric acid)} (Poly(3,4-BAHBA-co-4HCA) by thermal polycondensation of 4HCA and 3,4-BAHBA. When the 4HCA compositions of Poly(3,4-BAHBA-co-4HCA)s were above 55 mol%, the copolymers showed a nematic liquid crystalline phase due to the mesogenic effects of the continuous 4HCA units. Furthermore, these oriented films emitted polarized light.

Examined the unique opportunities of photomechanical responses realized in azobenzenefunctionalized LCP networks (both elastomers and glasses). Their work summarizes and contrasts the photomechanical response of glassy polydomain, monodomain, and twisted nematic azo-LCN materials to blue-green irradiation. These novel responses that may be of potential use in future employment of these materials in actuation.

Found that Photocontrol of molecular alignment is an exceptionally-intelligent and useful strategy. It enables us to control optical coefficients, peripheral molecular alignments, surface relief structure, and actuation of substances by means of photoirradiation. Azobenzene-containing polymers and functionalized LCPs are well-known photocontrollable materials. Photodriven changes in molecular alignment can play an important role in the future.

Introduced Liquid crystalline elastomers (LCEs) exhibiting a number of remarkable physical effects, including a uniquely high-stroke reversible mechanical actuation triggered by external stimuli. Fundamentally, all such stimuli affect the degree of liquid crystalline order in the polymer chains cross-linked into an elastic network The motivation for the combination of nanoparticles with LCEs is to provide better-controlled actuation stimuli, such as electric and magnetic fields, and broad-spectrum light, by selecting and configuring the appropriate nanoparticles in the LCE matrix.

In the same year, developed Magnetic hybrid liquid crystalline composites obtained either by thermal decomposition of a cobalt precursor in a solution containing a LCP or by dispersing preformed cobalt nanorods in a LCP matrix. The final materials are all mesomorphous and ferromagnetic. Coupling the inherent advantages of magnetic nanoparticles and liquid crystal groups could result in materials with interesting magnetic properties and orientational behavior, provided mechanical properties, which are mandatory for applications such as actuators.