This volume contains papers based on the main lectures, oral presentations and selected posters at the 5th International Conference on Polymer-Solvent Complexes and Intercalates held in Lorient in July 2004. The most relevant aspects of the polymer- and biopolymer-solvent interactions structure an dynamics in solutions, gels, solids and interfaces are presented in detail herein. the wide scope and up-to-date results are evidence of the growing impact of this field on various research areas ranging from material to life sciences.