Hydrophilic crosslinked polymer

A polymer based on a copolymer, which is in the form of polymeric particles, comprising

• a) at least one hydrophilically substituted alkyl vinyl ether of formula I
• where
• R1, R2, R3, independently of one another, is H or C1 to C6 alkyl, and
• R4 is a radical which carries at least one hydroxyl group,
• and
• b) at least one crosslinking agent of formula II and/or III and/or IV
• where
• X is a divalent alkyl radical having 2 to 5 C atoms in which one or more methylene groups which are not adjacent and are not located in the direct vicinity of N may be replaced by O, C═O, S, S═O, SO2, NH, NOH or N and one or more H atoms of the methylene groups may be substituted, independently of one another, by hydroxyl, C1-C6-alkyl, halogen, NH2, C5-C10-aryl, NH—(C1-C8)-alkyl, N—(C1-C8)-alkyl2, C1-C6-alkoxy or C1-C6-alkyl-OH,
• where
• Y1 and Y2 in formula III and IV
• are, independently of one another, C1 to C10 alkyl or cycloalkyl, where one or more non-adjacent methylene groups or methylene groups which are not located in the direct vicinity of N may be replaced by O, C═O, S, S═O, SO2, NH, NOH or N and one or more H atoms of the methylene groups may be substituted, independently of one another, by hydroxyl, C1-C6-alkyl, halogen, NH2, C5-C10-aryl, NH(C1-C8)alkyl, N(C1-C8)alkyl2, C1-C6-alkoxy or C1-C6-alkyl-OH, or
• C6 to C18 aryl, where one or more H atoms in the aryl system may be substituted, independently of one another, by hydroxyl, C1-C6-alkyl, halogen, NH2, NH(C1-C8)alkyl, N(C1-C8)alkyl2, C1-C6-alkoxy or C1-C6-alkyl-OH, and
• A is a divalent alkyl radical having 2 to 5 C atoms in which one or more non-adjacent methylene groups or methylene groups which are not located in the direct vicinity of N may be replaced by O, C═O, S, S═O, SO2, NH, NOH or N and one or more H of the methylene groups may be substituted, independently of one another, by hydroxyl groups, C1-C6-alkyl, halogen, NH2, C5-C10-aryl, NH(C1-C8)alkyl, N(C1-C8)alkyl2, C1-C6-alkoxy or C1-C6-alkyl-OH,
• wherein a) and b) have been copolymerized and the resultant polymer is in the form of polymeric particles.

A process for preparing a polymer, which is in the form of polymeric particles, comprising copolymerizing at least one hydrophilically substituted alkyl vinyl ether of the formula I and at least one crosslinking agent of formula II and/or III and/or IV to form said polymeric particles

• where
• R1, R2, R3, independently of one another, are H or C1 to C6 alkyl, and
• R4 is a radical which carries at least one hydroxyl group,
• and
• where
• X is a divalent alkyl radical having 2 to 5 C atoms in which one or more methylene groups which are not adjacent and are not located in the direct vicinity of N may be replaced by O, C═O, S, S═O, SO2, NH, NOH or N and one or more H atoms of the methylene groups may be substituted, independently of one another, by hydroxyl, C1-C6-alkyl, halogen, NH2, C5-C10-aryl, NH—(C1-C8)-alkyl, N—(C1-C8)-alkyl2, C1-C6-alkoxy or C1-C6-alkyl-OH,
• where
• Y1 and Y2 in formula III and IV
• are, independently of one another, C1 to C10 alkyl or cycloalkyl, where one or more non-adjacent methylene groups or methylene groups which are not located in the direct vicinity of N may be replaced by O, C═O, S, S═O, SO2, NH, NOH or N and one or more H of the methylene groups may be substituted, independently of one another, by hydroxyl, C1-C6-alkyl, halogen, NH2, C5-C10-aryl, NH(C1-C8)alkyl, N(C1-C8)alkyl2, C1-C6-alkoxy or C1-C6-alkyl-OH, or
• C6 to C18 aryl, where one or more H in the aryl system may be substituted, independently of one another, by hydroxyl, C1-C6-alkyl, halogen, NH2, NH(C1-C8)alkyl, N(C1-C8)alkyl2, C1-C6-alkoxy or C1-C6-alkyl-OH, and
• A is a divalent alkyl radical having 2 to 5 C atoms in which one or more non-adjacent methylene groups or methylene groups which are not located in the direct vicinity of N may be replaced by O, C═O, S, S═O, SO2, NH, NOH or N and one or more H of the methylene groups may be substituted, independently of one another, by hydroxyl, C1-C6-alkyl, halogen, NH2, C5-C10-aryl, NH(C1-C8)alkyl, N(C1-C8)alkyl2, C1-C6-alkoxy or C1-C6-alkyl-OH.