A microdroplet or microparticle with Janus or core-shell internal morphology, which is obtained under the control of phase separation of high-concentration NIPAAm formed at 25° C. or more in a microfluidic device, is provided. The microdroplet or microparticle shows an anisotropic volume change according to a change in temperature, and can also serve as a fat-soluble/water-soluble carrier, and thus can be used as a new material for medical supplies in the field of various applications in the future.

An N-vinyl amide polymer is disclosed. The N-vinyl amide polymer is a reaction product of: a monomer component comprising an N-vinyl amide; and a chain transfer agent of the formula:

##STR00001## wherein each occurrence of R.sub.1 is independently a C.sub.1-20 alkylene, a C.sub.1-20 heteroalkylene, a C.sub.3-20 cycloalkylene, a C.sub.3-20 heterocycloalkylene, a C.sub.6-20 arylene, or a combination thereof, and R.sub.1 is substituted or unsubstituted; R.sub.2 is a divalent or multivalent organic group having 2 to 40 carbon atoms; and n is at least 2.

An N-vinyl amide polymer is disclosed. The N-vinyl amide polymer is a reaction product of: a monomer component comprising an N-vinyl amide; and a chain transfer agent of the formula:

##STR00001## wherein each occurrence of R.sub.1 is independently a C.sub.1-20 alkylene, a C.sub.1-20 heteroalkylene, a C.sub.3-20 cycloalkylene, a C.sub.3-20 heterocycloalkylene, a C.sub.6-20 arylene, or a combination thereof, and R.sub.1 is substituted or unsubstituted; R.sub.2 is a divalent or multivalent organic group having 2 to 40 carbon atoms; and n is at least 2.

An N-vinyl amide polymer is disclosed. The N-vinyl amide polymer is a reaction product of: a monomer component comprising an N-vinyl amide; and a chain transfer agent of the formula: ##STR00001## wherein each occurrence of R.sub.1 is independently a C.sub.1-20 alkylene, a C.sub.1-20 heteroalkylene, a C.sub.3-20 cycloalkylene, a C.sub.3-20 heterocycloalkylene, a C.sub.6-20 arylene, or a combination thereof, and R.sub.1 is substituted or unsubstituted; R.sub.2 is a divalent or multivalent organic group having 2 to 40 carbon atoms; and n is at least 2.

An N-vinyl amide polymer is disclosed. The N-vinyl amide polymer is a reaction product of: a monomer component comprising an N-vinyl amide; and a chain transfer agent of the formula: ##STR00001## wherein each occurrence of R.sub.1 is independently a C.sub.1-20 alkylene, a C.sub.1-20 heteroalkylene, a C.sub.3-20 cycloalkylene, a C.sub.3-20 heterocycloalkylene, a C.sub.6-20 arylene, or a combination thereof, and R.sub.1 is substituted or unsubstituted; R.sub.2 is a divalent or multivalent organic group having 2 to 40 carbon atoms; and n is at least 2.

An active energy ray-curable resin composition for three-dimensional molding support materials is provided and includes 0.1 to 90% by mass of a non-polymerizable compound (A) in which inorganic groups/organic groups (I/O value) equals 0.4 to 1.8, and 10 to 99.9% by mass of a polymerizable compound (B) in which inorganic groups/organic groups (I/O value) equals 0.8 to 3.0. By using the active energy ray-curable resin composition, an ink for a support material having well-balanced inorganicity and organicity is obtained, and by using the ink, the support material is easily removed from a roughly molded product without corrosion of ink tanks, ink ejection heads, and similar objects, and a large-sized and highly accurate three-dimensional molded product is obtained.

An active energy ray-curable resin composition for three-dimensional molding support materials is provided and includes 0.1 to 90% by mass of a non-polymerizable compound (A) in which inorganic groups/organic groups (I/O value) equals 0.4 to 1.8, and 10 to 99.9% by mass of a polymerizable compound (B) in which inorganic groups/organic groups (I/O value) equals 0.8 to 3.0. By using the active energy ray-curable resin composition, an ink for a support material having well-balanced inorganicity and organicity is obtained, and by using the ink, the support material is easily removed from a roughly molded product without corrosion of ink tanks, ink ejection heads, and similar objects, and a large-sized and highly accurate three-dimensional molded product is obtained.

A separating medium for hydrophilic interaction chromatography useful in separating hydrophilic compounds. The hydrophilic interaction chromatography separating medium, which is formed from a support and a ligand carried by the support, is a separating medium wherein the ligand is a (meth)acrylic polymer having a constituent unit derived from the compound indicated by formula (I). ##STR00001##

A separating medium for hydrophilic interaction chromatography useful in separating hydrophilic compounds. The hydrophilic interaction chromatography separating medium, which is formed from a support and a ligand carried by the support, is a separating medium wherein the ligand is a (meth)acrylic polymer having a constituent unit derived from the compound indicated by formula (I). ##STR00001##

The present invention relates to a hydrogel and use thereof. More specifically, the present invention relates to a hydrogel comprising water and a polymer matrix, wherein the polymer matrix comprises a copolymer of a monofunctional monomer having a hydrophilic group and one ethylenic unsaturated group, and a polyfunctional monomer having no ester bond, and having an amide group and 3 to 6 ethylenic unsaturated groups, 40 to 95 parts by mass of the water, and 5 to 60 parts by mass of the polymer matrix are contained in 100 parts by mass of the hydrogel, and the hydrogel shows a swelling degree of 650% or less, when the hydrogel is immersed in a 4M aqueous KOH solution under a temperature of 25° C. for 14 days, and use thereof.