Polyether polymer, preparation process and use thereof

A process for preparing a polyether polymer having structural units represented by the general formula (1):

• ##STR26## wherein R1 and R2 mean individually an alkyl group of 1-20 carbon atoms, which may have one or more hydroxyl groups, and Y denotes an alkylene group of 1-10 carbon atoms, which may have a hydroxyl group, said polyether polymer having a weight-average molecular weight of 5,000-1,000,000, which process comprises reacting a polymer having structural units represented by the general formula (2):
• ##STR27## wherein R.sup.1 and R.sup.2 have the same meaning as defined above, with a .omega.-halocarboxylic acid or a salt thereof represented by the following general formula (3) or a cyclic lactone represented by the following general formula (4):
• ##STR28## wherein Y has the same meaning as defined above, Z denotes a halogen atom, M is a metal ion or a hydrogen atom, and m stands for a number of 1-8.