Preparation of liquid–crystal thermosets: In situ photopolymerization of oriented liquid–crystal diacrylates

✍ Scribed by Chain-Shu Hsu; Hwai-Len Chen

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 220 KB
• Volume: 37
• Category: Article
• ISSN: 0887-624X
• DOI: 10.1002/(sici)1099-0518(19991101)37:21<3929::aid-pola8>3.0.co;2-9

✦ Synopsis

The photoinitiated polymerization of 2-chloro-1,4-phenylene bis [4-[6-(acryloyloxy)hexyloxy]benzoate] (1M) was studied. The monomer 1M exhibited a broad nematic phase between 24.9 and 113.7 °C on a DSC cooling scan. It was oriented in its nematic phase at a substrate coated with polyimide and unidirectionally rubbed with a nylon cloth. During polymerization, the ordering of the liquid-crystal molecules was fixed, yielding a uniaxially crosslinked network. The clear liquid-crystal networks (LCNs) exhibited a birefringence between 0.14 and 0.19, depending on the polymerization temperature. Finally, a nonmesogenic diluent, tetra(ethylene glycol)diacrylate, was mixed with 1M, subsequently decreasing the birefringence of the obtained LCNs. The LCNs containing nonmesogenic diluent exhibited not only a smaller birefringence but also a weaker birefringence dispersion in the visible region.