LAYERED STRUCTURE WITH SIDE-CHAIN CRYSTALLINITY IN UNDOPED POLY(3-ALKYL THIOPHENES)

The order formation of alkyl-substituted rigid polymers, like poly(3-a lkyl thiophenes), is dependent on the length of the alkyl side chain. The formation of a layered structure can be observed by X-ray diffract ion experiments. A linear relationship with the d-spacing for (200) pl ane and n has been obtained along with the observation of the endother ms for the mesophase transition by the thermal analysis. The endotherm ic transition temperatures observed by DSC decrease with the increasin g number of carbons (n) in the alkyl side chain. Side chain crystalliz ation becomes possible when n is larger than 10, resulting in hexagona l packing of the alkyl chains between the main chain layers.