We report the effects of different intermolecular interactions on the properties of soluble dodecylbenzenesulphonate (DBS)-doped polypyrrole (PPY) and composites. The contribution of the intermolecular interactions to the optical properties of PPY and composites has been investigated by UV-vis transmission spectroscopy. Polymer-solvent interactions result in different chain conformations that are responsible for the changes in the absorption spectra of PPY(DBS). Some relevant differences between the filtered soluble fraction and the initial as-synthesised PPY(DBS) are demonstrated by the IR absorption spectra. In order to study how the molecular interaction between the components affects the properties of the composite, we mix different types of polymers: (i) doped polypyrrole and an undoped highly fluorescent polymer (methyl-substituted ladder-type polyparaphenylene, m-LPPP); (ii) doped polypyrrole and an electronically inert polymer (polymethylmethacrylate, PMMA). The changes induced by high pressures on the absorption spectra of PPY(DBS) and m-LPPP/PMMA/PPY(DBS) are discussed in terms of chain conformation changes and dipolar-dipolar interactions. The fast magic angle spinning (MAS) spectra of PPY(DBS) provide a structural and dynamical investigation on conjugated polymers based on 1 H NMR spectroscopy.