Phosphonato block polymer, preparation method therefor and application thereof

A method for preparing a phosphonic block polymer, characterized in that the phosphonic block polymer is prepared by the copolycondensation of ether-type fragment A, phosphonic fragment B and third-portion aldehyde C;

• the molar ratio of ether-type fragment A to phosphonic fragment B is 1:(0.8˜5.0);
• wherein, ether-type fragment A is obtained by the polycondensation of polyether monomer a and first-portion aldehyde C,
• the structural formula of polyether monomer a is shown as a-1, a-2, a-3, a-4 or a-5:
• wherein L1 is H, C1˜C10 alkyl or NR5R6, R5 and R6 are both C1˜C3 alkyl,
• and R1, R2, R3 and R4 are of polyoxyalkylene structures which are independent of each other:
• the polyoxyalkylene structure is composed of a polyoxyethylene structure and an optional polyoxypropylene structure, and the content of the polyoxyethylene structure is not lower than 60 mol %;
• the molecular weight of polyether monomer a is 1200˜4800;
• the phosphonic fragment B is obtained by the polycondensation of monomer b, monomer c and second-portion aldehyde C in an aprotic weakly-polar solvent E;
• the structural formula of monomer b is shown as b-1 or b-2 or b-3:
• wherein L2 is C2˜C10 linear alkylene or (AO)m, m=1˜5, AO is CH2CH2O and/or CH(CH3)CH2O, Y is H, OH, —COOH, —COOR7 or C1˜C8 alkyl, wherein R7 is C1˜C6 linear alkyl structure;
• wherein when L2 is C2-C10 linear alkylene, G is —N(CH2-PO3H2)2 and —NH—CH2PO3H2, when L2 is (AO)m, G is −PO3H2;
• monomers c is at least one of phenol, aniline, p-/o-aminobenzene sulphonic acid, p-/o-hydroxybenzoic acid, p-/o-aminobenzoic acid, p-/o-hydroxybenzene sulphonic acid, p-o-methylaniline or p-/o-methyl;
• monomer c is added in an amount of 1%˜10% of the molar amount of monomer b;
• aldehyde C is a C1˜C6 alkyl aldehyde, C7˜C12 aromatic aldehyde or glyoxylic acid;
• ether-type fragment A has a molecular weight of 2400˜96000 and a degree of polymerization of 2˜20;
• phosphonic fragment B has a molecular weight of 300˜43200 and a degree of polymerization of 2˜100;
• the phosphonic block polymer has a molecular weight of 6000˜100000.