Polysulfone polymers and membranes for reverse osmosis, nanofiltration and ultrafiltration

A modified polysulfone polymer containing repeat units selected from the group consisting of:

• -phenyl-X1-phenyl-SO2-phenyl-X2—;
• and
• -phenyl-X3-phenyl-X4-phenyl-SO2-phenyl-X5—;
• wherein
• each phenyl ring is linked to the next phenyl ring at the ortho, meta or para position;
• X1 to X5 are the same or different and each is O, S, P(R), P(O)(R), B(R), N(R), or R′, where R is an unsubstituted aliphatic or aromatic C1-C20 hydrocarbyl, or R is substituted by halogen or by a group containing a heteroatom selected from the group consisting of O, S, and N, and R′ is an aliphatic or aromatic C1-C20 hydrocarbylene or such hydrocarbylene interrupted by one or more heteroatoms selected from the group consisting of O, S, P(R), P(O)(R), B(R), and N(R), or substituted by one or more halogen, O, S, P(R)2, P(O)(R)2, B(R)2, N(R)2 or C1-C20 hydrocarbyl;
• and
• (a) two different phenyl rings are substituted ortho to the sulfone group by two or three identical or different functional groups selected from the group consisting of:
• (i) —CO—R1, wherein R1 is —OH, halohydrocarbyloxy, a mono- or oligosaccharide residue or a derivative thereof;
• (ii) —CON(R2)R3, wherein R2 is H or hydrocarbyl and R3 is a mono- or oligosaccharide residue or a derivative thereof;
• (iii) —B(OR2)2, wherein R2 is H or hydrocarbyl;
• and
• (iv) —P(═O)(OR2)2, wherein R2 is H or hydrocarbyl;
• or
• (b) one phenyl ring is substituted by a —B(OR2)2 group ortho to the sulfone group, wherein R2 is H or hydrocarbyl;
• or
• (c) a group —CO—O—R4—O—CO—, wherein R4 is alkylene, links two chains of the polymer backbone;
• provided that the modified polysulfone is not a carboxylated polysulfone comprising repeat units of the formula [-phenyl-C(CH3)2phenyl-O-phenyl-SO2-phenyl-O—] and two carboxy groups ortho to the sulfone group in the two phenyl rings adjacent to the sulfone group.