A method for producing conjugated diene rubber is provided, including: a first step of obtaining a conjugated diene polymer chain having an active end by polymerizing a monomer comprising a conjugated diene compound and a vinyl compound having a functional group interactive with silica using a polymerization initiator in an inert solvent; a second step of reacting a siloxane compound with the active end of the conjugated diene polymer chain having the active end; and a third step of reacting a hydrocarbyloxysilane compound with the conjugated diene polymer chain with which the siloxane compound has been reacted that is obtained in the second step.

A polymer composition comprising a star-branched copolymer having a plurality of arms is disclosed. Each polymer arm has a molecular weight Mp of from 1 kg/mol to 50 kg/mol and comprises polymerized units (i) derived from a first vinyl aromatic monomer comprising a radical-reactive group, wherein from greater than 10 mol % to 100 mol % of the units (i) are unhydrogenated; and optionally, polymerized units (ii) comprising hydrogenated and unhydrogenated forms of polymerized units derived from a high Tg monomer, and hydrogenated form of polymerized units (i) or hydrogenated form of polymerized styrene units; and optionally, polymerized units (iii) comprising (a) hydrogenated form of polymerized units derived from one or more acyclic conjugated dienes, and (b) polymerized units derived from one or more of a second vinyl aromatic monomer; wherein less than 10 wt. % of units (a) are unhydrogenated.

Disclosed is a copolymer including a first part including an aromatic vinyl-based monomer and a conjugated diene-based monomer; and a second part including an aromatic vinyl-based monomer and a conjugated diene-based monomer, wherein the content of the aromatic vinyl-based monomer is 35 to 45% by weight based on a total weight of the copolymer, and the copolymer satisfies Equation 1 below:

V.sub.1>V.sub.2 <Equation 1>

wherein V.sub.1 is a vinyl content in the first part, and V.sub.2 is a vinyl content in the second part.

A styrenic block copolymer having one or more polymer blocks A and one or more polymer blocks B is disclosed, where A is a poly(vinylaromatic) block having a molecular weight of greater than 5 kg/mol. The B block has a molecular weight of more than 15 kg/mol, and comprises polymerized 1,3-diene units and vinylaromatic units, wherein the polymerized vinylaromatic units represent 5-40 wt. % of the overall weight of the block B. The polymerized 1,3-diene units comprise more than 80 wt. % of polymerized isoprene units in which 45-80 mol % are 1,4-isoprene addition units. The blocks A and B represent from >5 to <40 wt. %, and >33 to <95 wt. %, respectively, relative to the overall weight of the block copolymer. The polymers have physical properties that make them valuable, e.g., as vibration damping materials.

A styrenic block copolymer is disclosed, having a formula, A-B-A, A-B-B-A, (A-B-A).sub.nX, (A-B).sub.nX or mixtures thereof, wherein n is from 2 to 30, and X is residue of a coupling agent. Each A block is independently a polystyrene having 10-63 wt. % 1,1-diphenylethylene, a GPC peak molecular weight from about 5-40 kg/mol, and forms 10-40 wt. % of the copolymer. Each B block is independently a poly(1,3-diene-co-styrene) comprising: (i) >90 wt. % of polymerized isoprene units relative to the weight of the polymerized 1,3-diene, where S is <40, and (S+V) is 18-75; (ii) >90 wt. % of polymerized butadiene units relative to the weight of the polymerized 1,3-diene, where S is <40, and (1.2*S+V) is 60-120; or combinations thereof S represents the polystyrene content, and V represents the 1,3-diene content having pendant 1,2- and/or 3,4-vinyl groups in the B block.

A method for producing conjugated diene rubber is provided, including: a first step of obtaining a conjugated diene polymer chain having an active end by polymerizing a monomer comprising a conjugated diene compound and a vinyl compound having a functional group interactive with silica using a polymerization initiator in an inert solvent; a second step of reacting a siloxane compound with the active end of the conjugated diene polymer chain having the active end; and a third step of reacting a hydrocarbyloxysilane compound with the conjugated diene polymer chain with which the siloxane compound has been reacted that is obtained in the second step.

A viscosity index improver containing a copolymer (A) whose essential constituent monomer is a monomer (a) having a number average molecular weight of 800 to 4,000 represented by the following formula (1), the copolymer (A) having a solubility parameter in the range of 9.00 to 9.40:

##STR00001##

wherein R.sup.1 is a hydrogen atom or a methyl group; X.sup.1 is a group represented by O, O(AO).sub.m, or NH, AO is a C2-C4 alkyleneoxy group, m is an integer of 1 to 10, each AO may be the same or different when m is 2 or more, and the (AO).sub.m moieties may be randomly bonded or block-bonded; R.sup.2 is a residue after removal of one hydrogen atom from a hydrocarbon polymer whose essential constituent monomer is butadiene in which the butadiene is present in a proportion of 50% by weight or more based on the weight of R.sup.2, or after removal of one hydrogen atom from a polymer formed by partial hydrogenation of the hydrocarbon polymer; and p represents a number of 0 or 1.

A binder composition for a non-aqueous secondary battery contains water-soluble macromolecules, water, and a particulate polymer formed of a polymer that includes a block region formed of an aromatic vinyl monomer unit. Surface acid content A of the particulate polymer is 0.05 mmol/g or more, acid content B in an aqueous phase of the binder composition per 1 g of the particulate polymer is not less than 0.03 mmol/g and not more than 0.80 mmol/g, and a ratio (A/B) of the surface acid content A of the particulate polymer and the acid content B in the aqueous phase of the binder composition is not less than 0.5 and not more than 5.0.

Tetrablock copolymers of formula ABAC are provided that can be used to form porous articles such as porous hollow fibers and porous membranes. Each A block is formed from a vinyl aromatic monomer, the B block is formed from a conjugated diene monomer, and the C block is formed from at least two different oxirane (i.e., epoxy) compounds. The tetrablock copolymers can advantageously be prepared without the use of functional initiators and/or difunctional initiators. The tetrablock copolymers are well suited for solvent induced phase separation (SIPS) processing to prepare porous articles. Membranes formed from the tetrablock copolymers can be used for water treatment and biopharmaceutical purification and/or separation processes.

Materials having structure (1), wherein R and R.sup.1 may be the same or different and each independently represents an alkyl or aryl group, X may be hydrogen or a C.sub.1 to C.sub.20 alkyl group which may be branched or linear and wherein the aromatic ring substituent joined to polymer B is positioned meta or para to the aromatic ring substituent joined to polymer A and, wherein polymer A is a non-polar polymer formed by metallocene catalysis and polymer B is a polymer formed by radical catalysis of a polar monomer are used as polymer additives particularly to improve the compatibility of mixtures of polymers. ##STR00001##