| 摘要 |
A cyclic compound comprising m units of the formula Ia:and n units of the formula (Ib):joined together to form a ring,wherein Y and Y2 are divalent bridging groups which may be the same or different in each unit;R0 is H or (C1-C6) alkyl or is a metal or ammonium cation;R5 is H or (C1-C60) alkyl or OH group;j is 1 or 2;R3 is hydrogen, a hydrocarbyl or a hetero-substituted hydrocarbyl group;each of R1, R2 and R4, which may be the same or different, is hydroxyl, hydrogen, hydrocarbyl or hetero-substituted hydrocarbyl,with the provisos thati) at least one of R1, R2, R4 is hydroxyl, and m+n is 4 to 20, m is 1-8 and n is at least 3, andii) in formula Ia at least one OH group is in the meta or para position to the COOR0 group and/or at least one R5 group is OH.
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