The instant invention concerns a process for fragmenting a polymer chain, comprising an oxidative degradation step wherein the polymer chain is contacted with a reduced form of a metal M and an oxidant such as dioxygen, and wherein the polymer carries covalently bound chemical groups acting as a ligand of said reduced form of the metal M.

The invention also relates to methods making use of this fragmentation process as a first step of a degradation process of the polymer especially useful for avoiding the negative impact of a polymer to the environment. In this connection, the invention relates to the use of polymers carrying chemical groups acting as a ligand for a reduced form of a metal M, as a polymer biodegradable in an environment wherein the reduced form of a metal M is present.

The instant invention concerns a process for fragmenting a polymer chain, comprising an oxidative degradation step wherein the polymer chain is contacted with a reduced form of a metal M and an oxidant such as dioxygen, and wherein the polymer carries covalently bound chemical groups acting as a ligand of said reduced form of the metal M.

The invention also relates to methods making use of this fragmentation process as a first step of a degradation process of the polymer especially useful for avoiding the negative impact of a polymer to the environment. In this connection, the invention relates to the use of polymers carrying chemical groups acting as a ligand for a reduced form of a metal M, as a polymer biodegradable in an environment wherein the reduced form of a metal M is present.

Hygroscopic hydrogels including a cross-linked polymer, the polymer being prepared by polymerization of one or more monomers, wherein at least one of the monomers is a compound of formula I, are provided. Related monomers and polymers, as well as methods for the production and use thereof, are also provided. Hygroscopic hydrogels as described herein may be used for water harvesting, for example. (I) (formula I)

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Hygroscopic hydrogels including a cross-linked polymer, the polymer being prepared by polymerization of one or more monomers, wherein at least one of the monomers is a compound of formula I, are provided. Related monomers and polymers, as well as methods for the production and use thereof, are also provided. Hygroscopic hydrogels as described herein may be used for water harvesting, for example. (I) (formula I)

##STR00001##

A polymer compound is provided which is changed from a water-insoluble state to a water-soluble state by irradiation with light. The polymer compound is represented by Formula (5), where A and B are a single bond or a functional group, R.sup.3, R.sup.4, and R.sup.9 are hydrogen or an alkyl group, and R.sup.6 and R.sup.7 are hydrogen, an alkyl group, or the like.

A polymer compound is provided which is changed from a water-insoluble state to a water-soluble state by irradiation with light. The polymer compound is represented by Formula (5), where A and B are a single bond or a functional group, R.sup.3, R.sup.4, and R.sup.9 are hydrogen or an alkyl group, and R.sup.6 and R.sup.7 are hydrogen, an alkyl group, or the like.

The active energy ray-curable liquid composition according to the present disclosure is an active energy ray-curable liquid composition that contains water and a curable substance and is curable with an active energy ray, in which the curable substance contains a monofunctional polymerizable monomer having a structure represented by the Formula (1);

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in Formula (1), R1 represents a hydrogen atom or a saturated hydrocarbon group, R2 represents a saturated hydrocarbon group that has at least one of a hydroxyl group or an amide bond and may contain a heteroatom, R3 represents a hydrogen atom or a methyl group, R1 and R2 may be bonded together to form an aliphatic heterocycle together with a nitrogen atom substituted with R1 and R2 in a case where R1 represents a saturated hydrocarbon group, and a total number of carbon atoms of the saturated hydrocarbon groups represented by R1 and R2 is 5 or more.

The active energy ray-curable liquid composition according to the present disclosure is an active energy ray-curable liquid composition that contains water and a curable substance and is curable with an active energy ray, in which the curable substance contains a monofunctional polymerizable monomer having a structure represented by the Formula (1);

##STR00001##

in Formula (1), R1 represents a hydrogen atom or a saturated hydrocarbon group, R2 represents a saturated hydrocarbon group that has at least one of a hydroxyl group or an amide bond and may contain a heteroatom, R3 represents a hydrogen atom or a methyl group, R1 and R2 may be bonded together to form an aliphatic heterocycle together with a nitrogen atom substituted with R1 and R2 in a case where R1 represents a saturated hydrocarbon group, and a total number of carbon atoms of the saturated hydrocarbon groups represented by R1 and R2 is 5 or more.

A process for preparing an acrylic emulsion resin is provided by introducing specific monomers at a certain time during an emulsion polymerization process, dispersion stability and adhesion properties of the acrylic emulsion resin are improved, thereby providing an aqueous acrylic pressure-sensitive adhesive that not only has excellent initial adhesion but also has low viscosity and improved processability, and high adhesion holding power.

A process for preparing an acrylic emulsion resin is provided by introducing specific monomers at a certain time during an emulsion polymerization process, dispersion stability and adhesion properties of the acrylic emulsion resin are improved, thereby providing an aqueous acrylic pressure-sensitive adhesive that not only has excellent initial adhesion but also has low viscosity and improved processability, and high adhesion holding power.