Addition-fragmentation oligomers of the general formula Z—B.sub.y-A-(B-A).sub.x-B-A-B.sub.y—Z, where the A monomers units are derived from a diester or diacid, the B monomer units are derived from a difunctional monomer having functional groups co-reactive with the acid or ester groups of the A monomer, x+y is zero to 60, Z comprises an ethylenically unsaturated, polymerizable group, A monomers comprise a 1-methylene-3,3-dimethylpropyl group, and at least one B monomer unit comprises a high refractive index group.

Provided are a composition for forming a transparent orthodontic device, a method of preparing a transparent orthodontic device, and a transparent orthodontic device prepared by using the method. The composition includes 100 parts by weight of a first photocurable compound represented by Formula 1, 35 parts by weight to 75 parts by weight of a second photocurable compound represented by Formula 2, 15 parts by weight to 65 parts by weight of a third photocurable compound represented by Formula 3, 5 parts by weight to 40 parts by weight of a fourth photocurable compound represented by Formula 4, and 1 part by weight to 15 parts by weight of a fifth photocurable compound represented by Formula 5.

Provided are a composition for forming a transparent orthodontic device, a method of preparing a transparent orthodontic device, and a transparent orthodontic device prepared by using the method. The composition includes 100 parts by weight of a first photocurable compound represented by Formula 1, 35 parts by weight to 75 parts by weight of a second photocurable compound represented by Formula 2, 15 parts by weight to 65 parts by weight of a third photocurable compound represented by Formula 3, 5 parts by weight to 40 parts by weight of a fourth photocurable compound represented by Formula 4, and 1 part by weight to 15 parts by weight of a fifth photocurable compound represented by Formula 5.

A hard coating film including a metal-free acrylate-based resin and having a water contact angle of about 40° or less and a pencil surface hardness of about 6H or more at a load of 1 kg; a composition for hard coating used in preparation of the hard coating film; a laminate including the hard coating film, a method of preparing the laminate; and an article including the laminate.

A hard coating film including a metal-free acrylate-based resin and having a water contact angle of about 40° or less and a pencil surface hardness of about 6H or more at a load of 1 kg; a composition for hard coating used in preparation of the hard coating film; a laminate including the hard coating film, a method of preparing the laminate; and an article including the laminate.

Photocurable compositions comprising 20-90% by weight of a polymerizable core resin; 20-90% by weight of a diluent resin miscible with said core resin; and at least about 1% by weight of at least one rheology modifier which is distinct from said diluent resin. Rheology modifiers of the present disclosure include compounds which may form covalent bonds with the core resin or diluent resin and compounds which have a particle size of 1-200 nm. Rheology modifiers which may form covalent bonds have at least one terminal functional group selected from the group consisting of acrylates, methacrylates, epoxides, oxetanes, nitriles, alkenes and alkynes.

Photocurable compositions comprising 20-90% by weight of a polymerizable core resin; 20-90% by weight of a diluent resin miscible with said core resin; and at least about 1% by weight of at least one rheology modifier which is distinct from said diluent resin. Rheology modifiers of the present disclosure include compounds which may form covalent bonds with the core resin or diluent resin and compounds which have a particle size of 1-200 nm. Rheology modifiers which may form covalent bonds have at least one terminal functional group selected from the group consisting of acrylates, methacrylates, epoxides, oxetanes, nitriles, alkenes and alkynes.

The present invention relates to a copolymer for the photoalignment of liquid crystals comprising a photoreactive group as given below in formula (I), compositions thereof, and its use for optical and electro optical devices, especially liquid crystal devices (LCDs).

The invention provides methods of reducing shrinkage stress in cross-linked polymerized materials by combining an addition-fragmentation chain transfer additive with a resin system prior to polymerization. The methods of the invention can improve the performance of conventional resin systems by reducing the shrinkage stress without significantly degrading the mechanical properties of the polymerized material. The shrinkage stress in the crosslinked polymeric materials produced by the methods of the invention may be from 25% to 75% of that of a control material produced by polymerization of the resin system alone to the same conversion.

A Addition-fragmentation oligomers containing allylic disulfide groups are described. The oligomers may be added to polymerizable compositions to provide labile crosslinks that can cleave and reform during the polymerization process.