Disclosed is a vinyl alcohol-based block copolymer that is a block copolymer composed of a vinyl alcohol-based polymer block (B-b) and a copolymer block (B-c) comprising a vinyl alcohol-based monomer unit and an acrylic acid-based monomer unit, wherein a content (Z) of the acrylic acid-based monomer unit relative to all monomer units is 0.05 to 20.0 mol %, the block copolymer has a saponification degree of 80 to 99.99 mol %, the block copolymer has a number-average molecular weight (Mn.sub.a) of 20,000 to 440,000, the block copolymer has a molecular weight distribution (Mw.sub.a/Mn.sub.a) of 1.05 to 1.95, and a ratio (DP.sub.b/DP.sub.a) of a number-average polymerization degree (DP.sub.b) of the vinyl alcohol-based polymer block (B-b) to the number-average polymerization degree (DP.sub.a) of the block copolymer is 0.010 to 0.999. The copolymer has a fine balance derived from the copolymer block (B-c) of having a superior solubility in water while being unlikely to undergo thickening or gelation due to pH fluctuation, and also has high mechanic strength derived from the vinyl alcohol-based polymer block (B-b).

A method for producing a fluorine-containing elastomer, which includes carrying out an emulsion polymerization of a fluorine-containing monomer in an aqueous medium in the presence of (A) a fluorine-containing compound containing a functional group capable of reaction by radical polymerization and a hydrophilic group and (B) a hydrocarbon surfactant to provide a fluorine-containing elastomer.

A method for producing a fluorine-containing elastomer, which includes carrying out an emulsion polymerization of a fluorine-containing monomer in an aqueous medium in the presence of (A) a fluorine-containing compound containing a functional group capable of reaction by radical polymerization and a hydrophilic group and (B) a hydrocarbon surfactant to provide a fluorine-containing elastomer.

The invention relates to a method for preparing a dry cationic hydrogel polymer product. The method comprises polymerisation of a reaction mixture comprising ethylenically unsaturated monomers in presence of water and initiator(s) by radical polymerisation and obtaining a hydrogel polymer. The hydrogel polymer is comminuted by chopping or shredding, and dried, whereby a dry hydrogel polymer product in powder form is obtained. At least one cationic reverse phase emulsion polymer is added to the hydro polymer at the comminuting step. The invention relates also to a dry cationic hydrogel polymer composition prepared by the method and its use.

Temperature-responsive poly(2-hydroxyethyl methacrylate) (PHEMA) and a preparation method thereof are disclosed. In the preparation method, with a system consisting of benzoyl peroxide (BPO) (an oxidant) and 2-methyl-N-[3-(methyl-phenyl-amino)-propyl]-acrylamide (MPAEMA) or 2-methyl-N-[3-(methyl-phenyl-amino)-propyl]-propionamide (MEMA) (a reducing agent monomer) as a redox initiation system, water and toluene as media, a nonionic surfactant as an emulsifier, and 2-hydroxyethyl methacrylate (HEMA) as a polymerization monomer, polymerization is conducted at room temperature and atmospheric pressure to obtain the PHEMA. An alcohol solution of the PHEMA has an upper critical solution temperature (UCST). The method has the advantages of simple and stable polymerization system, low polymerization cost, easy operation, mild conditions, small impact on the environment, and low energy consumption. Moreover, a molecular weight and UCST of a product are controllable within a specified range.

Temperature-responsive poly(2-hydroxyethyl methacrylate) (PHEMA) and a preparation method thereof are disclosed. In the preparation method, with a system consisting of benzoyl peroxide (BPO) (an oxidant) and 2-methyl-N-[3-(methyl-phenyl-amino)-propyl]-acrylamide (MPAEMA) or 2-methyl-N-[3-(methyl-phenyl-amino)-propyl]-propionamide (MEMA) (a reducing agent monomer) as a redox initiation system, water and toluene as media, a nonionic surfactant as an emulsifier, and 2-hydroxyethyl methacrylate (HEMA) as a polymerization monomer, polymerization is conducted at room temperature and atmospheric pressure to obtain the PHEMA. An alcohol solution of the PHEMA has an upper critical solution temperature (UCST). The method has the advantages of simple and stable polymerization system, low polymerization cost, easy operation, mild conditions, small impact on the environment, and low energy consumption. Moreover, a molecular weight and UCST of a product are controllable within a specified range.

Disclosed is a branched polymer which is a reaction product of reactants comprising one or more monoethylenically unsaturated ester monomers, a chain transfer agent in an amount of 0.1 to 15 weight percent, and a crosslinker in an amount of 0.1 to 15 weight percent of a crosslinker, wherein weight percent is based on total amount of reactants, provided the amount of crosslinker is within +/−5 weight percent of the amount of chain transfer agent, and wherein the crosslinker comprises at least two carbon-carbon double bonds having different reactivity. A thermosetting composition prepared by crosslinking the branched polymer and an acrylic polymer is also disclosed.

A redox curing dental composition comprising: a. one or more compounds having a radical polymerizable carbon-carbon double bond; b. a redox initiator system comprising
a reducing agent which is a compound of the following formula (I):

##STR00001## wherein R.sup.1 and R.sup.2 which may be the same or different, independently represent a C.sub.1-18 hydrocarbyl group, or R.sup.1 and R.sup.2 form together with the silicon atom to which they are bonded a 3 to 8-membered silicon-containing alicyclic ring, which groups R.sup.1 and/or R.sup.2 may be substituted with one to three substituents selected from the group consisting of a C.sub.1-6 alkoxy group, a halogen atom, or a carboxylic acid group; and
(ii) an oxidizing agent adapted to oxidize the reducing agent of formula (I) in the absence of light for generating a radical capable of initiating radical polymerization of the one or more compounds having a radical polymerizable carbon-carbon double bond.

A redox curing dental composition comprising: a. one or more compounds having a radical polymerizable carbon-carbon double bond; b. a redox initiator system comprising
a reducing agent which is a compound of the following formula (I):

##STR00001## wherein R.sup.1 and R.sup.2 which may be the same or different, independently represent a C.sub.1-18 hydrocarbyl group, or R.sup.1 and R.sup.2 form together with the silicon atom to which they are bonded a 3 to 8-membered silicon-containing alicyclic ring, which groups R.sup.1 and/or R.sup.2 may be substituted with one to three substituents selected from the group consisting of a C.sub.1-6 alkoxy group, a halogen atom, or a carboxylic acid group; and
(ii) an oxidizing agent adapted to oxidize the reducing agent of formula (I) in the absence of light for generating a radical capable of initiating radical polymerization of the one or more compounds having a radical polymerizable carbon-carbon double bond.

A vinyl acetate-ethylene copolymer emulsion and method of making the same. The vinyl acetate-ethylene copolymer emulsion is prepared by using a redox initiator. Where the redox initiator includes a salt of at least one metal selected from the group consisting of silver (Ag), platinum (Pt), copper (Cu), mercury (Hg), zinc (Zn), tin (Sn), lead (Pb), bismuth (Bi), cadmium (Cd) and chromium (Cr). The emulsion further includes an oligomer of a monocarboxylic acid selected from the group consisting of C.sub.1-C.sub.14 aliphatic monocarboxylic acid and C.sub.6-C.sub.14 aromatic monocarboxylic acid.