Liquid-crystalline polymer-poly amide

By far the largest group of liquid crystalline polymers containing imide groups are copoly(esterimide)s (PEIs). These have been sub-divided into flexible copolymers containing aliphatic spacers and wholly aromatic copolymers. There are several reports of copoly(amide-imide)s and copoly(ether-imide)s (both thermotropic and lyotropic) and these are treated separately. There are only a few examples of wholly aromatic imide containing LCPs, as polyimides frequently melt well above their decomposition temperature. Successful attempts have been made to incorporate flexible spacers, but in most instances the spacers are based on ether units, and the polymer is more strictly classified as a poly(etherimide). 

A typical example of a thermotropic liquid crystalline polymers is the polyesters and the mesogen substituted polysiloxane. The aromatic amide, the super strength fiber known commercially as Kevlar belongs to the lyotropic liquid crystalline polymers. The other important lyotropic liquid crystalline polymers are poly(7-benzyl-L-glutamate), abbreviated as PBLG, cellulose derivatives, the tobacco mosaic virus, etc. 

Glycidyl methacrylate copolymers Ethylene/butyl acrylate/maleic anhydride copolymers Styrene/ethylene-butylene/styrene block copolymer Poly(amide) (PA), MgO Silicone rubber and aminosilane Liquid crystalline polymers Improved impact strength Improved impact strength" Improved impact strength Improved electrical properties, in glass fiber applications" Improved mechanical properties" Viscosity reduction" ... 

Blends of Poly(amide imides) and Liquid-Crystalline Polymers... 

For the purpose of discussing mesophase formation in polymers it is conveiuent to partition the polymers into two categories and introduce abbreviations that refer to these categories. Polymerized liquid crystals, here abbreviated PLCs, are derived from known, low molecular weight monomer liquid crystals (MLCs) that contain polymerizable functionality (e.g. vinyl units). We designate liquid-crystalline polymers (LCPs) to be semiflexible, linear polymers that are structurally related to conventional engineering thermoplastics, i.e. polymers derived from poly(ester)s, poly(amide)s, poly(imide)s, etc. We will examine the attributes of polymerized liquid crystals first, stressing the similarities between their properties and those of MLCs. 

Di Y, lannace S, Di Maio E, Nicolais L (2003) Nanocomposites by melt intercalation based on polycaprolactone and organoclay. J Polym Sci Polym Phys Ed 41 670 Donald AM, Windle AH (1992) Liquid crystalline polymers. University Press, Cambridge Fukushima Y, Okada A, Kawasumi M, Kurauchi T, Kamigaito O (1988) Swelling behaviour of montmorillonite by poly-6-amide. Clay Miner 23 27 Greenland DJ (1963) Adsorption of poly(vinyl alcohols) by montmorillonite. J Colloid Sci 18 647 Han CD (2010) On the mechanism leading to exfoliated nanocomposites prepared by mixing. Adv Polym Sci 231 1-75... 

Scheme 6.6. Procedures for the preparation of poly(aryl amide) polymers. The carboxylic acid terminated polymers exhibited lyotropic liquid crystalline behavior.

J.D. Sudha, Synthesis and characterization of hydrogen-bonded thermotropic liquid crystalline aromatic-aliphatic poly(ester-amide)s from amido diol, J. Polym. Sci. A Polym. Chem. 38 (2000) 2469-2486. 

Poly(l,4-benzamide), abbreviated here as PpBA, was the first nonpeptide, synthetic condensation polymer reported to form liquid crystalline phases [11, 39,42,48-50]. Technologically important is poly(l,4-phenylene terephthalamide), abbreviated here as PpPTA. In both polymers the non-flexibility or semi-rigid chain structure is caused by the paralinked benzene rings and the partial double bond character of the carbon-nitrogen bond in the predominantly trans amide linkages. 

The intensity of the electron beam used to examine thin crystalline polymer films by electron microscopy is usually of sufficient intensity to induce cross-linking. It is not surprising, therefore, after initial examination in the crystalline state, that thin films of poly(amides) and polyethylene display ordered structures when subsequently examined in the molten state by this technique. These observations are to be expected. They cannot be construed as evidence that, in general, the liquid state in polymers is an ordered one.(33) The partially ordered liquid represents an interesting, unique situation that results from the nature of the chain arrangement at the time of network formation. 

De Candia F, Renzulli A, Vittoria V, Roviello A, Sirigu A (1990) Transport properties of a thermotropic liquid-crystalline polyester. J Polym Sci Part B Polym Phys 28 203-211 East AJ, Charbonneau LF, Calundann GW (1982) Poly(ester-amide) capable of forming an anisotropic melt phase derived from 6-hydroxy-2-naphthoic acid, dicarboxylic acid, and aromatic monomer capable of forming an amide linkage. US Patent 4,330,457, 18 May 1982 Fellahi S, Meddad A, Fisa B, Favis BD (1995) Weldlines in injection-molded parts a review. Adv Polym Technol 14 169-195... 

---