A composition for use as a stain blocker and a method of treating substrates therewith, said composition comprising a polymer of Formula 1 having the following repeating units in random sequence wherein R1 is H, methyl or ethyl; R2 and R3 are each independently H, C1 to about C10 alkyl, —COOR4, CONR5R6, or —CN; R4 is M, C1 to about C20 alkyl, or C6 to C10 aryl; R5 and R6 are each independently H, C1 to C10 alkyl, C6 to C10 aryl, or R5 and R6 together with the nitrogen atom form a morpholine, pyrrolidine, or piperidine ring; R7 is a C4 to C8 alkyl group; M is H, an alkali metal or alkali earth metal; h is about 10 to 100 mole %; i is 0 to about 80 mole %; j is 0 to about 60 mole %; k and n are each independently 0 to about 40 mole %; and m is 0.01 to about 0.5; provided that h+i+j+k+n equals 100, and provided that i+j+k+n is greater than zero, except when h is 100%.