| 摘要 |
A sequential block copolymer containing: (i) a moiety R<1>X derived from a starter molecule having at least one active hydrogen wherein R<1> is either an alkyl or alkaryl group having from 1 to 30 carbon atoms, X is O,S or N, (ii) a polymeric block derived from at least one alkylene oxide of formula CxH2xO wherein x is an integer from 2 to 4, and at least 50 mole % of said polymeric block is derived from an alkylene oxide where x is 3 or 4, and (iii) a polymeric block derived from at least one alkylene oxide of formula CyH2yO wherein y is an integer in the range from 6 to 30 characterised in that the sequential block copolymer has the formula: R<1>X-[(CyH2yO)m - (CxH2xO)n - H]q (I) wherein R<1>, X, y and x are as defined above, q is 1 when X is O or S, q is 2 when X is N; and m and n are such that the molecular weight is in the range from 600 to 4000 and the (CyH2yO) polymeric block (ii) derived from the alkylene oxide of formula CyH2yO forms from 1 to 40% by weight of the copolymer and the polymeric block derived from the alkylene oxide of formula CyH2yO constitutes the first polymeric block of the sequential block copolymer and is linked directly to the moiety R<1>Xis described. The alkylene oxide CxH2xO is preferably propylene oxide. The copolymer can be prepared by a two step process in which a starter molecule R<1>X(R<2>)q is reacted with CyH2yO to give an intermediate product which is then reacted with CxH2xO. |
