A transparent body production method that includes subjecting the compound represented by formula (1) to heating at a temperature equal to or greater than the melting point of said compound. In formula (1), each of W.sup.1 and W.sup.2 is the group represented by formula (2) in which the ring Z is an aromatic hydrocarbon ring, X is a single bond or S, R.sup.1 is a single bond or an alkylene group having 1-4 carbon atoms, R.sup.2 is a specific substituent, and m is an integer of 0 or higher, the group represented by formula (4) is OH or a (meth)acryloyloxy group, each of the rings Y.sup.1 and Y.sup.2 is an aromatic hydrocarbon ring, R is a single bond or a specific divalent group, each of R.sup.3a and R.sup.3b is CN, a halogen group, or a monovalent hydrocarbon group, and each of n1 and n2 is an integer of 0-4.

A transparent body production method that includes subjecting the compound represented by formula (1) to heating at a temperature equal to or greater than the melting point of said compound. In formula (1), each of W.sup.1 and W.sup.2 is the group represented by formula (2) in which the ring Z is an aromatic hydrocarbon ring, X is a single bond or S, R.sup.1 is a single bond or an alkylene group having 1-4 carbon atoms, R.sup.2 is a specific substituent, and m is an integer of 0 or higher, the group represented by formula (4) is OH or a (meth)acryloyloxy group, each of the rings Y.sup.1 and Y.sup.2 is an aromatic hydrocarbon ring, R is a single bond or a specific divalent group, each of R.sup.3a and R.sup.3b is CN, a halogen group, or a monovalent hydrocarbon group, and each of n1 and n2 is an integer of 0-4.

A compound of formula (I): can be used as a monomer for making an underwater adhesive polymer. The compound of formula (I) can be prepared using eugenol as a starting material. ##STR00001##

[Object] To provide a method for producing a vinyl ether polymer having a hydroxyl group on the side chain, wherein the vinyl ether polymer having a low viscosity and excellent workability and processability is produced in a simple and efficient method.

[Means for solving problem] The present invention relates to a method for producing a vinyl ether polymer having a hydroxyl group on the side chain, characterized in that vinyl ether comprising a hydroxyl group is subjected to radical polymerization by using an oil-soluble azo polymerization initiator, in the presence of a mixed solvent comprising water and an organic solvent selected from alcohol or cyclic ether radical polymerization.

A polyvinyl ether-based polymer useful as a gellant, having a structural unit represented by formula (2):

##STR00001## where R.sup.1 represents a linear or branched alkanediyl group having 1 to 5 carbon atoms, R.sup.2 represents a single bond or a linear or branched alkanediyl group having 1 to 5 carbon atoms, X represents C(?O)OH, C(?O)O-M.sup.+, or C(?O)O.sup.?, M.sup.+ represents a counter ion, and n is an integer of 0 to 3.

A polyvinyl ether-based polymer useful as a gellant, having a structural unit represented by formula (2):

##STR00001## where R.sup.1 represents a linear or branched alkanediyl group having 1 to 5 carbon atoms, R.sup.2 represents a single bond or a linear or branched alkanediyl group having 1 to 5 carbon atoms, X represents C(?O)OH, C(?O)O-M.sup.+, or C(?O)O.sup.?, M.sup.+ represents a counter ion, and n is an integer of 0 to 3.

A method for producing a hydroxyl group-containing vinyl ether polymer according to the present invention includes: a step of radical polymerizing at least one vinyl ether selected from vinyl ether having a hydroxyl group represented by the following formula (2):

##STR00001##

wherein R.sup.7 represents an alkylene group which is straight-chained, branched or comprises an alicyclic structure, and p is 1, 2, or 3, in the presence of water as a polymerization solvent and an azo compound represented by the following formula (1) as a polymerization initiator:

##STR00002##

wherein R.sup.1 to R.sup.4 each independently represent a hydrogen atom or an alkyl group and R.sup.5 and R.sup.6 each independently represent an alkoxy group optionally having a substituent group or an alkyl amino group optionally having a substituent group.

A method for producing a hydroxyl group-containing vinyl ether polymer according to the present invention includes: a step of radical polymerizing at least one vinyl ether selected from vinyl ether having a hydroxyl group represented by the following formula (2):

##STR00001##

wherein R.sup.7 represents an alkylene group which is straight-chained, branched or comprises an alicyclic structure, and p is 1, 2, or 3, in the presence of water as a polymerization solvent and an azo compound represented by the following formula (1) as a polymerization initiator:

##STR00002##

wherein R.sup.1 to R.sup.4 each independently represent a hydrogen atom or an alkyl group and R.sup.5 and R.sup.6 each independently represent an alkoxy group optionally having a substituent group or an alkyl amino group optionally having a substituent group.

To provide a method for producing a polymer that is capable of providing an alkenyl ether polymer having a molecular weight, a molecular weight distribution, and a composition that are controlled, with a vinyl ether having a hydroxyl group, and a block copolymer thereof. To provide a polymer obtained by the method as a macro chain transfer agent capable of performing reversible addition fragmentation chain transfer polymerization. Livingness can be imparted to radical polymerization of a hydroxyl group-containing vinyl ether by performing the radical polymerization in the presence of a particular RAFT agent and a radical polymerization initiator, and a block copolymer with another radically polymerizable vinyl monomer can be obtained by using the resulting living polymer as a macro chain transfer agent capable of performing reversible addition fragmentation chain transfer polymerization.

To provide a method for producing a polymer that is capable of providing an alkenyl ether polymer having a molecular weight, a molecular weight distribution, and a composition that are controlled, with a vinyl ether having a hydroxyl group, and a block copolymer thereof. To provide a polymer obtained by the method as a macro chain transfer agent capable of performing reversible addition fragmentation chain transfer polymerization. Livingness can be imparted to radical polymerization of a hydroxyl group-containing vinyl ether by performing the radical polymerization in the presence of a particular RAFT agent and a radical polymerization initiator, and a block copolymer with another radically polymerizable vinyl monomer can be obtained by using the resulting living polymer as a macro chain transfer agent capable of performing reversible addition fragmentation chain transfer polymerization.