DESCRIZIONE
The present invention provides a copolymer comprising repeat units of formulae (A), (B1 ) and/or (B2) and optionally (C): wherein in formula (A) R is selected from H and C1-6 alkyl; X1 is selected from COO, CONH and OCO; m is 0 or 1; R1 is selected from substituted or unsubstituted, linear or branched, C1-8 alkylene; n is 0 or 1; and R2 is a substituted or unsubstituted heterocyclyl, NRxRy, NHCORx or CONRxRy, wherein Rx and Ry are independently selected from substituted or unsubstituted, linear or branched, C1-8 alkyl, in formulae (B1 ) and (B2) R is selected from H and C1-6 alkyl; X2 is selected from COOR3 and OCOR3; o is 0 or 1; R3 is selected from substituted or unsubstituted, linear or branched, C1-8 alkylene; each R4 is independently selected from C1-10 alkyl and C5-10 aryl; in formula (B1 ) q is an integer from 1 to 160, and in formula (B2) q is 0 or an integer from 1 to 80, R5 is selected from C1-10 alkyl, C5-10 aryl or 0-Si(R6)3, wherein R6 is independently selected from C1-10alkyl and C5-10 aryl; and in formula (C): R is selected from H and C1-6 alkyl; and X3 is selected from COOH, COOR7, OCOR7,OH or OR7 wherein R7 is selected from substituted or unsubstituted, linear or branched, C1-8 alkyl; wherein said copolymer comprises 1 -40 wt% of repeat unit (A), a total of 10-90 wt% of repeat units (B1 ) and/or (B2) and 0 to 70 wt% of repeat unit (C).