A nanocrystal composite comprising a plurality of nanocrystals comprising a core comprising a metal or a semiconductive compound or a mixture thereof and at least one ligand, wherein said core is surrounded by at least one ligand, and a polythiourethane matrix, wherein said polythiourethane matrix is formed by thermal or UV induced nucleophilic addition of polyisocyanates having at least two isocyanate groups and polythiols having at least two thiol groups. Composite of the present invention provides improved thermal and photo thermal stability to the nanocrystals.

The invention relates to a water-dispersible modified polyisocyanate and use thereof, especially as a crosslinking component in water-soluble or water-dispersible coating compositions. The water-dispersible modified polyisocyanate can be obtained by the reaction of a system comprising a water-dispersible polyisocyanate and an isocyanate-reactive component; wherein the viscosity of the water-dispersible modified polyisocyanate is 3000 mPa.Math.s-11000 mPa.Math.s, which is measured with a MV-DIN rotor according to DIN EN ISO 3219:1994-10 at 23 C. and a shear rate of 10 s.sup.1. The modified polyisocyanate according to the present invention has good manual stirring behavior and good dispersibility, and the coating formed by the coating composition containing the modified polyisocyanate has high gloss and good transparency.