High molecular weight poly(diphenylacetylene) [PDPA] derivatives are introduced as fluorescent, soft conjugated polymers that exist in the gum state at room temperature. The gum-like behavior of the polymers is easily modified according to the side alkyl chain length and substitution position. Long alkyl chain-coupled PDPA derivatives provide soft and sticky gums at room temperature. Manual kneading of gum polymers produce soft films with very smooth surfaces. The gum polymers show an endothermic transition due to the melting of long alkyl chains. The X-ray diffraction of gum polymers reveals a new signal due to the molten aliphatic chains. The gum polymers show significant viscoelastic relaxation at the melting temperature of the alkyl side chains. The dynamic thermo-mechanical analysis (DTMA) of gum polymers at room temperature suggest that the meta-substituted polymer is softer and stickier than para-polymer. Rheological analysis suggests that the meta-polymer has less entanglement than para-polymer. The fluorescence emission of gum polymer is quite intense in the film and solution. The gum polymer film is readily stretched to produce a uniaxually oriented film. Stretching and subsequent relaxation of elastomer-supported gum polymer film generate buckles perpendicular to the axis of strain. The gum polymer film accommodates the large strain without cracking and delamination.