A quaternary ammonium sulfonamide compound of formula (I): wherein R=(II), C1-C3 linear or branched alkyl, R1 and R2 are the same or different and selected from C1 to C18 linear or branched alkyl, R3 and R4 are the same or different and selected from C1 to C4 linear or branched alkyl, CF3, OR5 where R5 is C1 to C8 linear or branched alkyl or polyethylene oxide, l is 1, 2, 3, 4, 5, 6, 7 or 8, m is 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 or 17, n is 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 or 18, wherein the aryl groups of R may be substituted or unsubstituted, X=halogen, and Y=(III) wherein R6, R7, R8, R9 and R10 are the same or different and selected from C1 to C6 linear or branched alkyl and the benzophenone is selected from the group consisting of substituted benzophenone and unsubstituted benzophenone, process for preparing the compound and antimicrobial surface coating compositions of the compound.