Present disclosure relates to a solvent-free method of encapsulating a hydrophobic active in personal care, hydrophobic active in crop protection or a hydrophobic active pharmaceutical ingredient (API) in polymeric nanoparticles. The method includes mixing the hydrophobic active in a polymer melt, wherein the polymer melt comprises a melt of a block co-polymer, wherein the polymer melt acts as a solvent for the hydrophobic active. The method further includes maintaining the polymer melt in water for sufficient time to allow self-assembly of the block co-polymer to encapsulate the hydrophobic active therein.