Polyethers, liquid crystalline thermal properties

Organometallic polyurethanes containing backbone polyether units have been reported.184,185 The incorporation of ferrocenyl segments into the backbone of polyurethanes enhanced thermal stability.186 There have been a number of studies on the incorporation of ferrocenyl units into the backbone of polyesters 101.187-191 A number of polymers of this class exhibited liquid crystalline properties.189-192 The thermal stability and glass transition temperatures of these polymers decreased with an increase in the length of the alkyl chains. 

Rausch also reported the synthesis of polyurethanes however, these polymers exhibited low solubihty and they precipitated from solution during the polymerization reactions. Polyurethanes with polyether segments in their backbones have also been synthesized. It has also been reported that polyurethanes with ferrocenyl units in their backbones exhibit enhanced thermal stability. Polyesters containing ferrocenyl units in the mainchain have been the focus of numerous studies. It has been reported that many of these organometallic polymers exhibit liquid crystalline properties. " Scheme 25 shows the synthesis of a liquid crystalline polyester (103) via polycondensation reactions. Increasing the length of the alkyl chains decreased the thermal stability and glass transition temperatures of these polymers. 

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