Cellulose nanocrystals (CNCs) are appealing building blocks to replace plastic for the fabrication of more sustainable photonic and barrier materials. Aqueous suspensions of CNCs are typically mixed with polymers to improve the mechanical flexibility of the dry nanocomposite, adding further functionalities. However, the role of the additives in the suspension state, and how they affect the processing and final properties of the material still requires further studies. In this work, the interactions between CNCs and polyethylene glycol diacrylate (PEGDA), a water-soluble, photocurable polymer, were investigated through a multi-scale approach involving small-angle X-ray and light scattering (SAXS and SALS). PEGDA was found to adsorb on the surface of CNCs, exhibiting two behaviour regimes depending on the mass ratio between PEGDA and CNCs (R