Preparation And Properties Of UV-curing Waterborne Polyurethane/Organosiloxane/SiO₂Nanocomposites

UV-curing waterborne polyurethane (WUPU) was widely concerned by researchersbecause it has advantages such as efficiency, energy saving, environmental, safety, etc.However, the mechanical and water resistance properties are poor compared with traditionalPU. To the question, different siloxane and nano-silica were incorporated into WUPU, a seriesdispersions and nanocomposite dispersions were obtained, and its properties of WUPU werestudied.(1) Hydroxyl-terminated siloxane was obtained by γ-aminopropyl triethoxysilane(APTES) and hydroxyethyl acrylate (HEA) with addition reaction, then the siloxane andnano-silica were incorporated into WUPU, its nanocomposite dispersions and films wereobtained. The influence of siloxane content, nano-silica content, surface properties andpreparation technology to the dispersion and film properties were discussed. Results showedthat when siloxane content was5%, nano-silica content was10%, the film has high tensilestrength (11.6MPa) and low water absorption (7.5%) when the alkaline nano-silica wasincorporated into WUPU by in situ method.(2) The polydimethysiloxane (PDMS) and nano-silica were incorporated to WUPU, theinfluence of PDMS content and nano-silica content to the dispersion and film properties werediscussed. Results showed that when PDMS content was8%, the film has good mechanicaland water resistance; when the nano-silica was incorporated into WUPU, SEM results showedthat nano-silica formed the continuous network and occupied the most part of the matrix,AFM results showed that some bright silica nanoparticles and its aggregated are dispersed inthe darker PDMS-rich domains, and surface roughness value of nanostructured films wasdecreased, the result was helpful to improve the surface abrasion and scratching resistance ofthe films. At the same tame, the nanocomposite films has a good surface hydrophobic (watercontact angle was104.7°) and water resistance (water absorption was6.2%), the tensilestrength (25.2MPa) improved obviously.(3) The block copolymer of PDMS with polycaprolactone diol (PCL-PDMS-PCL) andnano-silica were incorporated into WUPU, the influence of PCL-PDMS-PCL content andnano-silica content to the dispersion and film properties were discussed. Results showed thatwhen PCL-PDMS-PCL content was10%, the film has good mechanical and water resistance;PCL-PDMS-PCL content less than15%, the films holding a high level transmittance;.with theincorporation of nano-silica, the nanocomposite films have a good surface hydrophobic (watercontact angle was106.4°) and water resistance (water absorption was4.1%), the tensilestrength (34.0MPa) improved obviously.