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Phase Separation and Properties of UV‐Curable Polyurethane/Zirconia Nanocomposite Coatings
Author(s) -
Zhou Shuxue,
Wu Limin
Publication year - 2008
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.200800090
Subject(s) - nanocomposite , materials science , polyurethane , cubic zirconia , chemical engineering , zirconium , polymer chemistry , composite material , ceramic , metallurgy , engineering
Transparent zirconia (ZrO 2 ) nanocrystal dispersions in butyl acetate (BAc) or tetrahydrofuran (THF) were prepared by functionalizing zirconia nanocrystals, synthesized from a solvothermal reaction of zirconium (IV) isopropoxide isopropyl alcohol complex in benzyl alcohol, with 3‐methacryloxypropyltrimethoxysilane (MPS), and were embedded into UV‐curable polyurethane (PU) coatings. It was found that the ZrO 2 concentration was the dominating factor influencing the transparency of the ZrO 2 dispersion, while the molar ratio of MPS to ZrO 2 was rather efficient in adjusting the amount of MPS attached. Phase separation of the ZrO 2 nanocrystals in polyurethane coatings was observed, and was strongly related to the MPS‐modified ZrO 2 (MPS‐ZrO 2 ) content and the amount of MPS chemically bonded. The phase separation of the PU/ZrO 2 nanocomposite coatings appeared more seriously for higher MPS‐ZrO 2 content and higher amounts of MPS attached; thus the transparency of the nanocomposite coatings was lower. However, completely transparent PU/ZrO 2 nanocomposite coatings could be still achieved even with a ZrO 2 content up to 7.5 wt.‐% using a ZrO 2 /BAc dispersion. Improvements in pendulum hardness, microhardness and scratch resistance of the polyurethane coatings via addition of MPS‐ZrO 2 were demonstrated, but were not remarkable because of the low cross‐linking efficiency of the MPS‐ZrO 2 nanoparticles resulting from the poor compatibility of the MPS‐ZrO 2 nanoparticles with the pure PU oligomers.