Aggregates of the cationic conjugated polyelectrolyte (CPE) HTMA-PFP with poly(vinyl alcohol) (PVA) will be studied in aqueous solutions using SANS. Previous fluorescence, electrical conductivity, viscosity, NMR and SAXS studies suggest compact structures with the CPE encapsulated as core-shell particles within a PVA matrix. These have potential importance in optoelectronics and sensing, e.g. as emitting layers in LEDs. The proposed SANS study will provide more detailed insights by using specifically deuterated components. The experiments will study the two CPEs PBS-PFP and HTMA-PFP in water in the presence of PVA using various combinations of CPEs with deuterated PVA and water (i.e CPE/d3PVA/water, CPE/h3PVA/D2O and CPE/d3PVA/D2O) to obtain contrast. Combination of this data with our SAXS and molecular dynamics simulations will provide a detailed picture of the system.