Ethoxylated siloxane surfactants and hydrophilic silicones prepared therewith

DETAILED DESCRIPTION In the practice of the present invention, the curable silicone composition can be a one-part or multiple-part composition cured by the presence of adventitious moisture, crosslinking agents, catalysts, and/or heat.
Most preferred are two-part addition cure or condensation cure compositions of the room temperature vulcanizing ("RTV") variety.
The composition contains a "curable silicone prepolymer", that is, a polysiloxane having one or more functional groups which enable the prepolymer to be polymerized or cured to a state of higher molecular weight.
Suitable silicone prepolymers are well-known in the art and are described, for example, in "Silicones", Kirk-Othmer Encyclopedia of Chemical Technology, 3rd Ed.
, 20, 922-962 (1982), the disclosure of which is incorporated herein by reference.
The surfactant contains one or more siloxane solubilizing groups which render the surfactant soluble or dispersible in the silicone prepolymer.
The surfactant also contains one or more water-loving groups which render a cured composition of the invention hydrophilic.
The water-loving groups are ethyleneoxy (--C.
sub.
2 H.
sub.
4 O--) groups or hydroxyalkyl-substituted ethyleneoxy (e.
g.
, --CH.
sub.
2 CH(CH.
sub.
2 OH)O--) groups.
For brevity, these water-loving groups will sometimes be collectively referred to hereafter as "ethyleneoxy" groups.
The ethyleneoxy group(s) can be attached to the siloxane solubilizing group through either end of an ethyleneoxy group, that is, through a carbon atom or an oxygen atom of the ethyleneoxy group.
The surfactant preferably contains at least four ethyleneoxy groups (that is, the subscript m in the formula shown above preferably is at least four), and more preferably it contains at least ten to twenty such groups.
The number of ethylenoxy groups should not be so large that the surfactant becomes waxy, as that may reduce its effectiveness.
The surfactant also can contain other groups or substituents, if present in types and amounts which do not interfere with the functioning of such surfactant in the present invention or with the curing of the silicone prepolymer