Phase Separation and Properties of UV-Curable Polyurethane/Zirconia Nanocomposite Coatings

Transparent zirconia (ZrO2) 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‐methacryloxypropyltr...

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Bibliographic Details
Published in:Macromolecular chemistry and physics 2008-06, Vol.209 (11), p.1170-1181
Main Authors: Zhou, Shuxue, Wu, Limin
Format: Article
Language:English
Subjects:
Applied sciences
Composites
Exact sciences and technology
Forms of application and semi-finished materials
nanocomposite coatings
phase separation
Polymer industry, paints, wood
polyurethane oligomers
properties
Technology of polymers
zirconia nanocrystals
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Summary:Transparent zirconia (ZrO2) 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 ZrO2 concentration was the dominating factor influencing the transparency of the ZrO2 dispersion, while the molar ratio of MPS to ZrO2 was rather efficient in adjusting the amount of MPS attached. Phase separation of the ZrO2 nanocrystals in polyurethane coatings was observed, and was strongly related to the MPS‐modified ZrO2 (MPS‐ZrO2) content and the amount of MPS chemically bonded. The phase separation of the PU/ZrO2 nanocomposite coatings appeared more seriously for higher MPS‐ZrO2 content and higher amounts of MPS attached; thus the transparency of the nanocomposite coatings was lower. However, completely transparent PU/ZrO2 nanocomposite coatings could be still achieved even with a ZrO2 content up to 7.5 wt.‐% using a ZrO2/BAc dispersion. Improvements in pendulum hardness, microhardness and scratch resistance of the polyurethane coatings via addition of MPS‐ZrO2 were demonstrated, but were not remarkable because of the low cross‐linking efficiency of the MPS‐ZrO2 nanoparticles resulting from the poor compatibility of the MPS‐ZrO2 nanoparticles with the pure PU oligomers.
ISSN:1022-1352
1521-3935
DOI:10.1002/macp.200800090