A method wherein surfaces are provided with desired characteristics of a polymer by covalently bonding polymer molecules to the surface through external activation of latent reactive groups carried by the polymer molecules is disclosed. The initial surfaces are free of chemical groups added by surface pretreatment and which chemically participate in the covalent bonding process.This application is a divisional of application Ser. No. 223,149, filed July 22, 1988 now abandoned, which is a continuation-in-part of U.S. application Ser. No. 138,226, filed Dec. 24, 1987 now abandoned, which is a continuation-in-part of U.S. application Ser. No. 920,567, filed Oct. 17, 1986 now abandoned and of U.S. Ser. No. 108,765, filed Oct.15, 1987 now U.S. Pat. No. 4,973,493 which is a continuation-in-part of U.S. application Ser. No. 428,074 now U.S. Pat. No. 4,722,906 filed Sept. 29, 1982, and of U.S. application Ser. No. 920,567 filed Oct. 17, 1986.