Poly[ethynylene(3-n-butyl-2,5-thiophenediyl)-ethynylene]: A Soluble Polymer Containing Diacetylene Units and its Conversion to a Highly Cross-Linked Organic Solid

We are engaged in a program directed at the synthesis and study of highly cross-linked organic solids. Our approach has been to prepare low molecular weight polymers and oligomers consisting of aromatic moities linked by diacetylene units, to cross-link the diacetylenic units thermally, and to examine the properties of the resulting solids. Our initial efforts were directed toward the preparation of monomers having as high a ratio of carbon to hydrogen as possible.^1,2 Although this approach yielded materials with interesting properties (high Young's modulus, hardness, and thermal stability) the oligomeric/polymeric intermediates had poor solubility and high cure energies (in some cases exceeding 500 J/g) ; these values of cure energy made the preparation of large pieces difficult.