Highly hydrophilic/superhydrophilic organic coatings have good dirt resistance in air and excellent antifouling performance underwater.Unfortunately, traditional top organic coatings, such as polyurethane coatings, fluorocarbon polymer coatings, and polysiloxane coatings, are weakly hydrophobic or hydrophobic.Photocatalytic TiO2 nanoparticles and fluoride siloxane (for example, GH-701) were ever used to enhance the surface hydrophilicity of organic coatings.But the former will considerably shorten the service life of organic coatings and the latter easily causes the pigmented coatings gel during storage.Herein, we presented two kinds of modified silica nanoparticles, namely, light-responsive silica nanoparticles (SiO2-NBS-F) and PEG-modified SiO2 nanoparticles (SiO2-PEG).The SiO2-NBS-F nanoparticles were prepared by grafting of a light-responsive silane coupling agent (NBS) and further bonding with hydrophobic segments via a click reaction.They exhibited considerable change of wettability from near-superhydrophobicity to near-superhydrophilicity after UV irradiation.The SiO2-NBS-F nanoparticles were incorporated into fluorocarbon FEVE coatings.The nanoparticles easily occurred at the surface of the dried coatings even though their content was as low as 5 wt%,being due to their low surface free energy.The wettability of the SiO2-NBS-F filled FEVE coatings could transform from hydrophobicity (WCA 106.4°) to hydrophilicity (WCA 33.3°) after UV irradiation.The SiO2-PEG nanoparticles were prepared by grafting with PEG-bearing silane coupling agent that was synthesized using triethoxysilylpropyl isocyanate and excessive PEG.The SiO2-PEG nanoparticles were incorporated into acrylic-based polyurethane (APU) coatings.Transparent and crack-free nanocomposite coatings with SiO2-PEG content up to 35 and 40 wt% was achieved for SiO2-PEG400 and SiO2-PEG1000, respectively.Highly hydrophilic surface with water contact angle (WCA) as low as 38.7° was reached for the SiO2-PEG embedded coatings after inducing with water because of rearrangement of hydrophilic/hydrophobic segments.Moreover,SiO2-PEG400 was more efficient to enhance the surface hydrophilicity of the APU coatings than SiO2-PEG1000 at the same SiO2-PEG content.In contrast, pure APU coatings and the APU coatings containing unmodified SiO2 nanoparticles displayed WCAs of 68.2° and 70.1 o, respectively.Outdoor exposure experiments showed that the APU coatings containing SiO2-PEG nanoparticles had excellent dirt-resistance.