Abstract: An alkaline soluble maleimide tetrapolymer of Formulae I or II prepared by the free radical polymerization of the monomers maleimide, N-alkyl maleimide, (methyl)methacrylate and either (meth)acrylic acid or (meth)acrylate: wherein R is an alkyl having I to 4 carbon atoms; each R1, R2 and R3 is individually selected from hydrogen or methyl; each m is the mole fraction of maleimide and has a value of 5 to 20%, each n is a mole fraction of N-alkyl maleimide and has a value of about 50 to 70%, each x is the mole fraction of methyl(meth)acrylate and has a value of about 15 15 to 30%, y is the mole fraction of (meth)acrylic acid and has a value 3 to 12%, and z is the mole fraction of (meth)acrylamide and has a value of about 4 to 15%, wherein the values of m, n, x, y in Formula I and m, n, x and z in Formula II are such that the total nitrogen content of the maleimide tetrapolymer is at least about 6.5% by weight of the polymer.