Studies on partially polymerized 2,4-hexadiyn-1,6-bis(p-toluenesulfonate)

An improved procedure for the synthesis of high-purity 2,4-hexadiyn-1,6-bis(p-toluenesulfonate) (PTS) is described. The melting point of partially polymerized PTS increases monotonically with increasing polymer conversion (<12%). The increase in melting point is due to formation of a solid solution of unreacted monomer and polymer chains. The relation between the melting point and polymer conversion can be used for determination of polymer conversion. The low-conversion (<12%) polyPTS is soluble in dimethylformamide. The solution is yellow (lambda/sub max/ approx. = 450 nm) and does not undergo a color change when the temperature is lowered or a nonsolvent is added. Gel permeation chromatography (GPC) studies show that the molecular weight distribution of polyPTS is very broad and does not change with increasing polymer conversion up to <12%. The degree of polymerization for the low-conversion polyPTS is very low, about 20 repeat units. The G value for initiation centers (radicals) is about 2. The properties of the low-conversion partially polymerized PTS are compared with the corresponding properties of poly