Aromatic Main-Chain Polymers

The increasing use of optical fibre in the telecommunications network will, ultimately, require all-optical signal processing to exploit the full bandwidth available. This has led to a search for materials with fast, large third order optical nonlinearities. Most of the current materials either respond in the nanosecond regime or the nonlinearity is too small (1-3). Organic materials are attractive because of their ultra-fast, broadband responses and low absorption. However the main problem in the materials studied to date, e.g. polydiacetylenes (4) and aromatic main chain polymers (5), has been the small nonlinear coefficients. 

Table 3. Radiochemical Yields of Formation of Free Radicals in Aromatic Main-Chain Polymers... 

The polymer matrices used in HEMs can be divided by chemical structure into two major categories aromatic main-chain polymers and aliphatic main-chain... 

The aromatic main-chain polymer family includes poly(aryl ether suUbnes), poly (arjd ether ketones), poly(ar)d ethers), poly(phenylenes), poly(aryl benzimidazoles), and poly(ar)d imides). 

Jo TS, Kim SH, Shin J, Bae C. Highly efficient incorporation of functional groups into aromatic main-chain polymer using iridium-catalyzed C—H activation and Suzuki— Miyaura reaction. J Am Chem Soc. 2009 131 1656-1657. 

Chang Y, Lee HH, Kim SH, Jo TS, Bae C. Scope and regioselectivity of iridium-catalyzed C—H borylation of aromatic main-chain polymers. Macromolecules. 2013 46 1754-1764. 

Proton-conducting ionomers for polymer electrolyte membrane fuel cell (PEMFC) is one area in which extensive research is ongoing to modify aromatic main chain polymers to tailor their properties as proton conductors [1-... 

Jannasch, P. (2005) Imel cell membrane materials by chemical grafting of aromatic main-chain polymers. Fuel Cells, 5, 248-260. 

The thermotropic aromatic main chain liquid crystalline polymers are also prepared by the phase transfer catalyzed aromatic nucleophilic polymerization [87]. Polyetherification of bis(4-chloro-3-nitrophenyl) sulfone with mesogenic aromatic diols is shown below ... 

Aromatic polyesters were particularly good candidates for this new field of thermotropic main-chain polymers, since the relatively low energy of association of the ester groups led to low inter-chain forces. Further research led to the discovery that incorporation of 2,6-naphthylene or of 4,4 -biphenylyl groups, in addition to p-phenylene groups, as components of aromatic polyesters, introduced a useful new degree of randomness. Particularly useful, and the basis of the commercial products Vectra (polymer) and Vectran (fibre) from Hoechst-Celanese and Kuraray, are the copolymers formed by polymerisation of mixtures of p-acetoxybenzoic acid and 6-acetoxy-2-naphthoic acid. Within a range of... 

Aromatic Main Chain Liquid Crystalline Polymers... 

It is far beyond the scope of this chapter to present a comprehensive overview on the different structures of aromatic main chain LCPs and take into account the various property and application aspects. The objective of this chapter is to discuss the impact of structural concepts in modifying the properties of aromatic LCPs, focusing here on aromatic thermotropic LC polyesters. This will be discussed for selected examples. Conclusions from the work on polyesters are transferrable to other classes of thermotropic and lyotropic aromatic polymers. 

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