A block copolymer consists mainly of structural units each derived from an ethylenically unsaturated monomer and has at least one mercapto group. The block copolymer has an Mn of 5,000-500,000 and has a block structure, which is an A-B-A triblock structure or a star-shaped block structure of [A-B]qX. The q is an integer of 2-6. The polymer block (A) has a glass transition temperature of 20° C. or higher. The polymer block (B) of the triblock structure has a glass transition temperature lower than 20° C., and the [polymer block (B)]qX of the star-shaped block structure has a glass transition temperature lower than 20° C. The X is an initiator residue or/and a coupling-agent residue or is a derivative thereof.

A graft copolymer including zwitterionic repeat units and hydrophobic repeat units, in which the zwitterionic repeat units constitute 2-60 wt % of the graft copolymer and each of the hydrophobic repeat units is characterized in that a homopolymer formed thereof is miscible with polyvinylidene fluoride, polysulfone, poly ether sulfone, polyvinyl chloride, or polyacrylonitrile, each of the hydrophobic repeat units not being a repeat unit of polyvinylidene fluoride. Also disclosed is a filtration membrane containing such a graft copolymer or a statistical copolymer that includes the same composition of repeat units as the graft copolymer. Further disclosed are methods of preparing the graft copolymer and the filtration membrane.

The present invention relates to an anionic polymerization initiator represented by Formula 1 below for producing a polyolefin-polystyrene block copolymer, an anionic polymerization initiator composition, and a production method therefor,

##STR00001##

wherein R.sub.1, and A are described herein.

The present invention relates to an anionic polymerization initiator represented by Formula 1 below for producing a polyolefin-polystyrene block copolymer, an anionic polymerization initiator composition, and a production method therefor,

##STR00001##

wherein R.sub.1, and A are described herein.

A block copolymer (A) including a vinyl alcohol-based polymer block (b) and an ionic polymer block (c) containing a monomer unit with an ionic group forming a salt and a vinyl alcohol-based monomer unit. The ionic group is a carboxylic acid group, a sulfonic acid group, or an ammonium group. The vinyl alcohol-based polymer block (b) has a number-average molecular weight (Mn.sub.b) from 15,000 to 220,000. The ionic polymer block (c) has a content of the vinyl alcohol-based monomer unit from 5 to 95 mol % based on the total monomer units. The block copolymer (A) has a number-average molecular weight (Mn.sub.A) from 20,000 to 440,000. A ratio (Mn.sub.b/Mn.sub.A) of the number-average molecular weight (Mn.sub.b) to the number-average molecular weight (Mn.sub.A) is from 0.1 to 0.9.

A block copolymer including a first block consisting of a polymer having a repeating structure of a structural unit (u1) containing no silicon atom, and a second block consisting of a polymer having a repeating structure of a structural unit (u2) containing a silicon atom, the second block containing a block (b21) consisting of a polymer having a repeating structure of a structural unit (u21) represented by general formula (u2-1) shown below, and the volume ratio of the first block, based on all blocks constituting the block copolymer being 42 to 44 vol %: ##STR00001## In which R.sup.P211 represents an alkyl group, a halogenated alkyl group, a hydrogen atom, or an organic group having a polar group; and R.sup.P212 is a group derived from a compound represented by formula SHR.sup.t1, wherein R.sup.t1 represents a hydrocarbon group having 1 to 5 carbon atoms optionally having a substituent.

A block copolymer including a first block consisting of a polymer having a repeating structure of a structural unit (u1) containing no silicon atom, and a second block consisting of a polymer having a repeating structure of a structural unit (u2) containing a silicon atom, the second block containing a block (b21) consisting of a polymer having a repeating structure of a structural unit (u21) represented by general formula (u2-1) shown below, and the volume ratio of the first block, based on all blocks constituting the block copolymer being 42 to 44 vol %: ##STR00001## In which R.sup.P211 represents an alkyl group, a halogenated alkyl group, a hydrogen atom, or an organic group having a polar group; and R.sup.P212 is a group derived from a compound represented by formula SHR.sup.t1, wherein R.sup.t1 represents a hydrocarbon group having 1 to 5 carbon atoms optionally having a substituent.

Provided is a hydrogenated block copolymer, which is a hydrogenation product of a block copolymer including a polymer block (A) containing more than 70 mol % of a structural unit derived from an aromatic vinyl compound and a polymer block (B) containing 30 mol % or more of a structural unit derived from at least one selected from the group consisting of a conjugated diene compound and isobutylene, the hydrogenated block copolymer being satisfied with the following requirements (1) and (2): Requirement (1): the content of the polymer block (A) in the block copolymer is 1 to 30% by mass; and Requirement (2): when the polymer block (B) is regarded as having a structure with a hydrogenation rate of 100 mol %, an average value of a methylene chain length of a main chain of the structural unit derived from at least one selected from the group consisting of a conjugated diene compound and isobutylene is 1.0 to 6.0.

The present invention is directed to a rubber composition comprising an elastomer, a filler, and a block-copolymer. According to the invention, the block-copolymer comprises (i) an elastomer block and (ii) a thermoplastic block comprising a poly alkylacrylate, wherein the alkylacrylate comprises a polycyclic substituent at its single bonded oxygen atom. Moreover, the present invention is directed to a block-copolymer.

A vinyl chloride resin composition includes a vinyl chloride resin (A), an acrylic block copolymer (B) including a polymer block (b1) containing acrylic acid ester units and a polymer block (b2) containing methacrylic acid ester units, and a gelation accelerator (C), where the weight average molecular weight of the acrylic block copolymer (B) is in the range of 100,000 to 250,000, the content of the polymer block (b2) in the acrylic block copolymer (B) is in the range of 10 to 25 mass %, and the vinyl chloride resin composition contains 20 to 150 parts by mass of the acrylic block copolymer (B) and 4 to 18 parts by mass of the gelation accelerator (C) with respect to 100 parts by mass of the vinyl chloride resin (A).