According to one embodiment, a pattern formation material is included in a polymer layer to be provided between a block copolymer layer and a substrate. The block copolymer layer includes a block copolymer including a plurality of blocks. The pattern formation material includes a pattern formation polymer. The pattern formation polymer consists of a main chain including an acrylic backbone, and a side chain. One of the plurality of blocks include a plurality of polymer components. The plurality of polymer components are of mutually-different types. A solubility parameter of the pattern formation material is between a maximum value and a minimum value of a solubility parameter of the polymer components.

A block copolymer and a method for preparing the same are disclosed. The method comprises the following steps: (A) mixing a compound of formula (I), a catalyst of formula (II), and a first solvent to obtain a first mixture; (B) adding a first monomer into the first mixture for reaction to obtain a second mixture; and (C) adding a second monomer into the second mixture for reaction to obtain a third mixture; wherein the compound of formula (I) and the catalyst of formula (II) are as defined in the specification.

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 resin composition is provided which has high transparency, light guiding properties and luminescent properties and can guide light therethrough with little change in chromaticity. A shaped article such as an optical element including the resin composition is also provided. The resin composition includes an acrylic block copolymer (A) and a light diffusing agent (B), wherein the acrylic block copolymer (A) has at least one structure in which polymer blocks (a1) based on methacrylic acid ester units are bonded to both ends of a polymer block (a2) based on acrylic acid ester units, and has a weight average molecular weight of 10,000 to 150,000 and a tensile elastic modulus of 1 to 1,500 MPa, the light diffusing agent (B) is rutile titanium oxide having an average particle size of 0.5 to 2.0 m, and the content of the light diffusing agent (B) is 0.5 to 10 ppm (on mass basis) based on the acrylic block copolymer (A).

The invention provides an acrylic block copolymer which has excellent transparency, profile extrusion properties and surface smoothness of shaped articles, and which is also excellent in light guiding properties. The acrylic block copolymer includes a polymer block (a1) predominantly containing methacrylic acid ester units and a polymer block (a2) predominantly containing acrylic acid ester units, and has a refractive index of 1.485 to 1.495 and an order-disorder transition temperature (ODTT) of not more than 260 C.

Described is a polymerizable polymer composition compri a) a copolymerizable macromer, b) a (meth)acrylate ester monomer; and c) a polyfunctional type I photoinitiator.

A selective modification method of a base material surface includes subjecting at least a part of a surface of a base material to at least one surface treatment selected from the group consisting of an oxidization treatment and a hydrophilization treatment. The base material includes a surface layer and includes an oxide, a nitride or an oxynitride of silicon, or a combination thereof in a first region of the surface layer. A nonphotosensitive composition is applied directly or indirectly on the surface of the base material after the surface treatment. The nonphotosensitive composition includes: a first polymer containing a nitrogen atom; and a solvent. It is preferred that the base material contains a metal in a second region which is other than the first region of the surface layer. In the surface treatment step, an O.sub.2 plasma treatment is preferably conducted.

It is an object of the present invention to provide a pattern forming method capable of easily forming a phase-separated structure with high accuracy, even in the case of widening the applicable range of a pattern size. The present invention relates to a pattern forming method comprising: applying an under coating agent onto a substrate, and applying a self-assembly composition for pattern formation to the surface of the substrate, onto which the under coating agent has been applied, and then forming a self-assembly film according to self-assembly phase separation, wherein the self-assembly composition for pattern formation comprises a block copolymer comprising a polymerization unit (a) having at least one selected from a structure represented by a formula (103) and a structure represented by a formula (104), and a polymerization unit (b) having a structure represented by a formula (105).

The present application may provide a block copolymer and a use thereof. The present application may provide a block copolymer and a use thereof. The block copolymer of the present application may have excellent self-assembly properties or phase separation characteristics and simultaneously have characteristics capable of changing the self-assembly structure formed once, or provide a block copolymer capable of forming a pattern of phase separation structures in a polymer membrane.

The present application may provide a block copolymer and a use thereof. The present application may provide a block copolymer and a use thereof. The block copolymer of the present application may have excellent self-assembly properties or phase separation characteristics and simultaneously have characteristics capable of changing the self-assembly structure formed once, or provide a block copolymer capable of forming a pattern of phase separation structures in a polymer membrane.