lkylsilyl derivatives; and R??? is a linking group such as alkylene, cycloalkylene or phenylene. wherein n is integer???1; and the polyol moiety is formed from polyethylene glycol, polypropylene glycol, poly tetramethylene glycol, polyester diol, polyalkylene diol or a fluorinated polyether diol; wherein n is an integer???1; and the polyol moiety is formed from polyethylene glycol, polypropylene g