We have recently embarked on a new 1 year project funded by Michelin to explore the self-associatation and mechanical properties of telechelic rubbery materials. Such materials are of obvious interest due to their potential to associate into extremely resilient structures at ambient temperatures or dissociate into relatively fluid, processable materials at elevated temperature. Here we propose to explore their association behaviour in the presence of an unfunctionalised polymer; a realistic possibility for multicomponent industrial products as well as of interest as a fundamental study. We will explore this behaviour for a model system of polybutadiene and polyisoprene, moderately compatible, LCST. Blends of telechelic functionalised polyisoprene and perdeuterated polybutadiene will be studied by SANS to understand the association, interaction parameters and approach to phase boundary.