STUDIES ON PARTIALLY POLYMERIZED 2,4-HEXADIYN-1,6-BIS(PARA-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 ( less than 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 ( less than 12%) polyPTS is soluble in dimethylformamide. The solution is yellow ( lambda (max) congruent 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 less than 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 low-conversion partially polymerized PTS are compared with the corresponding properties of poly(Diacetylene diurethanes).