Process for preparing water-soluble polymers in powder form by polymerization of water-soluble monoethylenically unsaturated monomers comprising the successive steps: a) Spraying on the inner wall of a polymerization vessel, the lubricant composition LC1: alkyl oleate/polyoxyethylene oleyl ether phosphate/sorbitan monolaurate, b) Polymerizing in aqueous solution in the presence of polymerization initiators at least one water-soluble monounsaturated ethylenic monomer, c) Discharging the polymer gel, d) Granulating the polymer gel thus obtained in a granulator, in presence of a lubricant composition LC2: alkyl oleate/polyxoyethylene oleyl ether phosphate/sorbitan monol aurate, e) Drying the polymer gel to obtain a polymer in powder form, f) Grinding and sifting the powder.

Process for preparing water-soluble polymers in powder form by polymerization of water-soluble monoethylenically unsaturated monomers comprising the successive steps: a) Spraying on the inner wall of a polymerization vessel, the lubricant composition LC1: alkyl oleate/polyoxyethylene oleyl ether phosphate/sorbitan monolaurate, b) Polymerizing in aqueous solution in the presence of polymerization initiators at least one water-soluble monounsaturated ethylenic monomer, c) Discharging the polymer gel, d) Granulating the polymer gel thus obtained in a granulator, in presence of a lubricant composition LC2: alkyl oleate/polyxoyethylene oleyl ether phosphate/sorbitan monolaurate, e) Drying the polymer gel to obtain a polymer in powder form, f) Grinding and sifting the powder.

A lubricant adheres to a magnetic recording medium via at least one of chemisorption or bonding, and contains a perfluorinated polyether attached to or terminated with a functional group that is phosphonic acid, silanol or carboxylic acid, and may be:

R.sub.1R.sub.fR.sub.1 where R.sub.f is CF.sub.2O(CF.sub.2CF.sub.2CF.sub.2CF.sub.2O).sub.n, CF.sub.2O(CF.sub.2CF.sub.2CF.sub.2O).sub.nCF.sub.2, CF.sub.2O[CF(CF.sub.3)CF.sub.2O].sub.nCF.sub.2, CF.sub.2O(CF.sub.2CF.sub.2O).sub.m(CF.sub.2O).sub.nCF.sub.2, CF.sub.2O(CF.sub.2CF.sub.2O).sub.nCF.sub.2, n, m is from 1 to 100 and R.sub.1 is the functional group. A lubricant is formed from a multiple ether segments according to formula:

Re.sup.1Rb.sup.1-Ri-Rc-Ri-Rb.sup.2Re.sup.2; where Rc includes perfluoroalkyl ether, Rb.sup.1 and Rb.sup.2 are, independently, a sidechain segment including a perfluoroalkyl ether, optional Ri independently is a divalent linking segment including a functional group including elements from periodic table Group 13-17, and of Re.sup.1 and Re.sup.2 are phosphonic acid, silanol or carboxylic acid. Lubricant synthesis includes reacting a perfluorinated polyether with a halogenated functional group, selected from phosphonic acid, silanol or carboxylic acid.

In one embodiment, a multidentate perfluoropolyether (PFPE) lubricant has the formula S.sub.e-S.sub.o-S.sub.i-S.sub.L-S.sub.i-S.sub.o-S.sub.e, where each S.sub.o includes at least one perfluoroethyl ether unit, S.sub.L is a linker segment, and each S.sub.e and S.sub.i include at least one functional group configured to attach to a surface. In another embodiment, a multi dentate PFPE lubricant has the formula S.sub.e-S.sub.o(a)-S.sub.i-S.sub.m-S.sub.i-S.sub.o(b)-S.sub.e, where each S.sub.o(a), S.sub.o(b), and S.sub.m include at least one perfluoroethyl ether unit with the proviso that S.sub.m has a different number of perfluoroethyl ether units than at least one of So.sub.(a) and S.sub.o(b), and each S.sub.e and S.sub.i include at least one functional group configured to attach to a surface.

The present invention relates to an agent in particular for the surface epilamization of an article comprising one or more molecules having the general formula (1)
A-F(1)
wherein: A is an anchor group comprising a moiety selected from the group consisting of silane groups, hydroxyl groups, catechol groups, phosphate groups, phosphonate groups, carboxylic acid groups, amine groups, thiol groups and any combination of two or more of the aforementioned groups and F is a functionalizing group, wherein the functionalizing group com-prises a branched polymer having a backbone and at least two side groups, wherein at least one of the side groups is a C1-20 hydrocarbon group or a perhalogenated C1-20 hydrocarbon group. The invention pertains to the technical field of epilame for timepiece mechanical parts.