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Highly durable superhydrophobic, oleophobic and anti-icing coatings and methods and compositions for their preparation

  • US 9,067,821 B2
  • Filed: 04/07/2011
  • Issued: 06/30/2015
  • Est. Priority Date: 10/07/2008
  • Status: Expired due to Fees
First Claim
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1. A hydrophobic coating on a substrate prepared by a method comprising:

  • a) applying to said substrate a coating composition, comprising i) a binder, ii) first particles having a size of about 30 microns to about 225 microns, and iii) a solvent, to provide a base coating; and

    b)applying to said base coating a composition comprising second particles having a size of about 1 nanometer to 25 microns, wherein, prior to the application of the second particles to the base coating,i) the second particles have been modified with hexamethyldisilazane,ii) the second particles comprise covalently bound polydimethylsiloxane, oriii) the second particles comprise one or more covalently bound moieties independently selected from the group consisting of alkyl, haloalkyl and perfluoroalkyl moieties, which one or more moieties are covalently bound to said second particles by reaction of the particles with a silanizing agent of formula (I), said compound of formula (I) having the structure;


    R4-nSi—

    Xn



    (I)where n is an integer from 1 to 3;

    each R is independently selected from(i) C1 to 20 alkyl optionally substituted with one or more fluorine atoms;

    or(ii) —

    Z—

    ((CF2)q(CF3))r, wherein Z is a C1-12 divalent alkane radical or a C2-12 divalent alkene or alkyne radical, q is an integer from 1 to 12, and r is an integer from 1-4;

    each X is independently selected from the group consisting of —

    H, —

    Cl, —

    I, —

    Br, —

    OH, —

    OR2, —

    NHR3, and —

    N(R3)2;

    each R2 is an independently selected C1 to 4 alkyl or haloalkyl group; and

    each R3 is an independently selected H, C1 to 4 alkyl or haloalkyl group;

    wherein said coating has a contact angle with water that is greater than about 120°

    at a temperature of 18°

    C. to 23°

    C.;

    wherein the coating has a surface in contact with the substrate and an exposed surface comprising the binder that is not in contact with the substrate, the exposed surface having an arithmetical mean roughness from about 0.2 microns to about 20 microns, or a ten point mean roughness from about 1 micron to about 90 microns;

    wherein, in the resulting coating, the first particles are primarily distributed within and coated with the binder and the second particles are primarily distributed on the exposed surface;

    andwherein the coating has a greater number of second particles on the exposed surface than on the surface in contact with the substrate.

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