The invention provides copolymers of ethylenically unsaturated monomers
and of ethylenically functionalized nanoparticles in the form of their
aqueous polymer dispersions or water-redispersible polymer powders,
obtainable by means of free-radically initiated polymerization in an
aqueous medium and, if desired, subsequent drying of the resultant
polymer dispersion, ofA) one or more monomers from the group consisting
of vinyl esters, (meth)acrylic esters, vinylaromatics, olef ins,
1,3-dienes, vinyl ethers and vinyl halides and, if desired, further
monomers copolymerizable therewith, in the presence ofB) at least one
particle P having an average diameter of .ltoreq.1000 nm, which is
functionalized with ethylenically unsaturated, free-radically
polymerizable groups, characterized in thatB2) particles P used are one
or more from the group of metal oxides and semimetal oxides, and/orB2)
particles P used are silicone resins composed of repeating units of the
general formula [R.sup.4.sub.(p+Z)SiO.sub.(4-p-Z)/2] (II), where for at
least 20 mol % of the respective silicone resin p+z=0, 1 or 3,and where
B1) and B2) are each functionalized with one or more
.alpha.-organosilanes of the general formula
(R.sup.1O).sub.3-(R.sup.2).sub.nSi--(CR.sup.3.sub.2)--X (I), where X is a
radical having 2 to 20 hydrocarbon atoms and containing an ethylenically
unsaturated group.