Highly uniform gel and method for producing the same

Abstract

This gel contains a polymer prepared by crosslinking a plurality of branched monomers or branched polymers, and a good solvent of said plurality of branched monomers or branched polymers, and the aforementioned polymer in the gel has a crosslinking density greater than or equal to the concentration of overlap between the chains of mutually adjacent branched monomers or branched polymers of the aforementioned plurality of branched monomers or branched polymers.

Description

Technical Field

[0001] The present invention relates to a highly uniform gel based on the bond percolation theory.

Background Art

[0002] An ordered three-dimensional network structure with nanopores is important in a wide range of applications such as filtration, sensing, drug release, electronics, and optics. Methods for forming precise structures with nanometer resolution include nanolithography, metal-organic structures, etc., but the size of the resulting entire structure is limited to several μm 3 and even with current technology, the scale that can be manufactured is still limited, so it is extremely difficult to construct a three-dimensional structure of a size that can be handled by hand (~1 cm 3 ).

[0003] On the other hand, flexible gel materials typified by jelly are common soft materials around us, and are widely used in diapers, water retention agents for cosmetics, electrolyte carriers for lithium-ion batteries, separation membranes for DNA or proteins, and sustained-release carriers for drugs such as anticancer agents. Polymer gels are well-known soft materials composed of a huge three-dimensional polymer network structure having pores of nanometer size (~10 -9 m) throughout their bulk (Non-Patent Document 1). The network structure of the gel can be synthesized on a large scale without limitation in principle by crosslinking long-chain polymer chains with a crosslinking agent in a solvent. Gels have a characteristic that other materials do not have, that is, although they are materials with nanopores, they can be grown to a size that can be handled by hand by simple chemical synthesis.

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the network structure of the formed gel generally contains many defects and is highly non-uniform. Specifically, as a result of a completely stochastic gelation reaction, substantial levels of defects, including dangling ends, loops, entanglements, and non-uniform pore sizes, are inevitably present in the gel network structure (M. Shibayama, Macromol. Chem. Phys. 199, 1 - 30 (1998); M. Zhong, et al., Science 353, 1264 - 1268 (2016)). Such defects result in a non-uniform distribution of polymer chains, i.e., spatial defects, which are typically detected by light or neutron scattering techniques such as small-angle scattering, static laser speckle, and non-ergodic concentration fluctuations. To remove these defects from polymer gels, many attempts have been made, such as the synthesis of polymer gels from monodisperse polymer chains (J. E. Mark, et al, J. Chem. Phys. 66, 1006 - 1011 (1977)), the use of relatively uniform cross-linking processes such as photoreaction (T. Ngai, J. Phys. Chem. B108, 5532 - 5540 (2004)), the limitation of unwanted intramolecular reactions via A - B type cross-linking of star polymers (T. Sakai, Macromolecules 41, 5379 - 5384 (2008)), and the cross-linking of polymer chains with mobile cross-linking agents (Y. Okumura, et al., Adv. Mater. 13, 485 - 487 (2001)). However, distinguishable signs of spatial defects have been constantly observed in gels (T. Ngai, supra; T. Sakai, supra). Gels have been considered inherently disordered because the reaction proceeds stochastically as the polymers in solution move randomly. For this reason, the application of gels as nanostructured objects has been hindered.

[0006] The present inventors have broken this preconception, and the problem to be solved by the present invention is to provide a polymer gel having a highly ordered network and a simple and universal method for producing the same.

Means for Solving the Problem

[0007] To achieve the above object, the present invention includes, for example, the following aspects.

[0008] According to one aspect of the present invention, there is provided a gel including a polymer prepared by crosslinking a plurality of branched monomers or branched polymers, and a good solvent for the plurality of branched monomers or branched polymers, wherein the polymer in the gel is crosslinked at a concentration equal to or higher than a concentration at which chains of adjacent branched monomers or branched polymers among the plurality of branched monomers or branched polymers overlap each other.

[0009] According to another aspect of the present invention, there is provided a composition including a plurality of branched monomers or branched polymers, and a good solvent for the branched monomers or branched polymers, wherein the plurality of branched monomers or branched polymers are arranged in the good solvent at a concentration equal to or higher than a concentration at which chains of adjacent branched monomers or branched polymers overlap each other.

[0010] According to another aspect of the present invention, there is provided a method for producing a gel including a polymer prepared by polymerizing a plurality of branched monomers or branched polymers, the method including mixing a plurality of branched monomers or branched polymers in a good solvent at a concentration equal to or higher than a concentration at which chains of adjacent branched monomers or branched polymers among the plurality of branched monomers or branched polymers overlap each other, and polymerizing the plurality of branched monomers or branched polymers to obtain a gel.

Brief Description of the Drawings

[0011]

Figure 1

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Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Mode for Carrying Out the Invention

[0012] As used herein, "branched monomer" and "branched polymer" are molecules that are constituent units of a polymer that polymerizes to form a gel. A "branched polymer" has a portion where a plurality of the same monomers are polymerized.

[0013] As used herein, "(meth)acryl" refers to acrylic, methacrylic, or both.

[0014] As used herein, "gel" generally refers to a dispersion system of polymers with high viscosity and loss of fluidity, and refers to a state having a relationship of G' ≧ G'' in the storage elastic modulus G' and the loss elastic modulus G'', and is typically a substance having a three-dimensional network structure.

[0015] As used herein, hydrogel refers to a state in which the gel contains a solvent such as water inside.

[0016] In this specification, "wt%" can be used interchangeably with "mass%".

[0017] The strategy of the present inventors is to prepare a uniform gel based on the "bond percolation" model. "Bond percolation" is one of the classical percolation models together with "site percolation" and "site-bond percolation".

[0018] Percolation theory is a theory that considers what kind of clusters are formed and when clusters of the same size as the space are formed, that is, when percolation occurs, when particles bind to each other to form clusters within a limited space.

[0019] As shown in Fig. 1(A), in the site percolation and site-bond percolation models, the reaction system is partially filled with reactive units (solid gray spheres (X)) at the initial stage. The units can diffuse between sites, and percolation is controlled by diffusion (S. Corezzi, et al., Soft Matter 8, 11207-11216 (2012)), and two units bind when they are adjacent to each other. The resulting percolating network structure inevitably includes dense cross-linked regions and coarse cross-linked regions. Various spatial forms of the units occur in the developed network structure as a result. The white structure (Y) indicates the percolated network structure.

[0020] On the other hand, as shown in Fig. 1(B), in the bond percolation model, all spaces are initially pre-filled by mutually exclusive units. In other words, the state is shown where all sites have been occupied by units consisting of multifunctional molecules (gray spheres (X)) from the start before crosslinking. Each individual gray sphere (X) exhibits a strong volume exclusion effect. Percolation occurs as a result of crosslinking between adjacent units, and the reaction is controlled (S. Corezzi, et al., supra). The degree of intermolecular connectivity determines the gelation point. Although the shape of the connected molecules changes during the reaction, all sites remain occupied. The red structure (Y) indicates a network structure where percolation has occurred. Since the units are mutually exclusive, the space is always filled by the units regardless of the degree of crosslinking or network formation, which leads to a highly ordered ideal network structure after the reaction is completed.

[0021] In past studies, due to the insufficient volume exclusion effect of the units, the units were unable to fill the space either at the initial stage or during the crosslinking reaction, and the conditions for bond percolation were not fully satisfied.

[0022] The present inventors used a branched monomer or a branched polymer as a space-filling unit, and by densely filling the branched monomer or the branched polymer in solution before crosslinking, a state was created in which the branched monomer or the branched polymer in the solution consistently filled the space from before crosslinking to after crosslinking, creating a gel with an extremely uniform final crosslinked structure. The crosslinking reaction that proceeds with the space in the solution always being uniformly filled corresponds to bond percolation, which has existed conceptually since the 1950s, but this is the first time it has been realized in a real system.

[0023] A description will be given with reference to Fig. 2. In order to achieve this ideal bond percolation, the inventors of the present application first use a branched monomer or a branched polymer as a space-filling unit (Fig. 2(A)). Here, as the branched monomer or the branched polymer, poly(ethylene glycol) having four arms, which is a star polymer, is used. The reason for using a polymer having a plurality of arms such as PEG having four arms is to exhibit a strong volume exclusion effect that prevents other monomers (which may themselves be polymers) from spreading.

[0024] Next, to ensure that the branched monomer or the branched polymer uniformly and densely fills the space as assumed by the bond percolation model, the branched monomer or the branched polymer is dissolved in a good solvent at a concentration sufficiently exceeding the concentration at which the branched chains of the branched monomer or the branched polymer overlap (Fig. 2(B)). The good solvent is selected as a solvent that exhibits excellent affinity for the branched monomer or the branched polymer used in this study in order to prevent the chains of the branched monomer from separating during crosslinking (Fig. 2(B)). In the present specification, a good solvent for a plurality of branched monomers or branched polymers refers to a solvent in which no aggregates are observed when the solvent in which a plurality of branched monomers or branched polymers are dissolved is measured by dynamic light scattering. If the solubility of the branched monomer or the branched polymer in the solvent is low, the branched monomer or the polymer forms aggregates, but the presence or absence of aggregates can be determined from the time correlation function g2 with respect to the delay time τ. Specifically, when a solution of a branched monomer or a polymer (at a concentration equal to or higher than the overlap concentration) is measured by dynamic light scattering, only one relaxation (cooperative diffusion) is observed in a good solvent, and the relaxation becomes faster as the polymer concentration increases. On the other hand, when the quality of the solvent is insufficient, two relaxations are observed (hereinafter referred to as a fast relaxation and a slow relaxation), the slow mode corresponds to the aggregates, and the fast mode corresponds to the cooperative diffusion. Here, anhydrous acetonitrile is exemplified as a good solvent.

[0025] Furthermore, in order to remove as much air and nanobubbles as possible from the solution, the solution was filtered through a syringe microfilter with an average pore size of 20 nm (Fig. 2(C)).

[0026] Although the problems of the above respective processes have been individually pointed out in past research, they have not been solved together in one system.

[0027] After adding a stoichiometric amount of a crosslinking agent to the solution (Fig. 2(D), where a small molecule difunctional crosslinking agent is used as the crosslinking agent here), the star polymer solution undergoes a sol-gel transition (Fig. 2(E)).

[0028] A more accurate gelation point can be measured as the intersection of the storage modulus G' and the loss modulus G" by dynamic viscoelasticity measurement (H. H. Winter et al, J. Rheol. 30, 367-382 (1986)). The gelation point could be measured as the intersection of the storage modulus G' and the loss modulus G" by dynamic viscoelasticity measurement (Fig. 5(E)).

[0029] Here, the elastic modulus is a physical property inherent to a network polymer having a gel and an elastomer. In the theory of rubber elasticity, the shear elastic modulus (G') of the network polymer is the sum of the elasticities of each elastically effective chain in the network structure and is given by the following formula (S1).

[0030]

Equation

[0031] In the formula, v is the number density of elastically effective chains, k B is the Boltzmann constant, and T is the absolute temperature.

[0032] In a phantom network model (W. W. Graessley, Macromolecules 8, 186-190 (1975)), in order to consider the mobility of branch points, the following formula (S2) is given.

[0033]

Equation

[0034] Here, μ is the number density of branch points.

[0035] To estimate ν and μ, a tree-like approximation can be used, and the following equation (S3) can be obtained.

[0036] [Number]

[0037] Here, u4 is the number density of branched star polymers (tetra-PEG-NHS) in the gel, and p is the connectivity of the end groups (D. R. Miller et al, Macromolecules 9, 206-211(1976), Y. Tsuji et al., Gels 4, 50 (2018)).

[0038] Thus, according to the strategy of the present inventors, the space is always uniformly filled with units of the starting branched monomer or branched polymer throughout the gelation reaction, and the pre-gel solution is restricted in shape. By densely packing the polymer in the solution before gelation, the cross-linking conditions based on the bond percolation theory can be realized, and the polymer can maintain a uniformly dispersed state even after gelation.

[0039] The nanometer structure in the gel can be evaluated by using static laser light scattering (SLS) and small-angle x-ray scattering (SAXS) to obtain the spatial function of the branched monomer or branched polymer chain in the Fourier space. SAXS covers the real space on a wide length scale from ~2 nm to ~60 nm, and SLS covers from ~250 nm to ~920 nm.

[0040] And the gel with a uniform network of the present invention is not only expected to be applied as a high-performance separation membrane, but also because abnormal light scattering due to structural inhomogeneity does not occur, the theoretical upper limit of transparency achievable as a soft material can be realized (Figure 2(F)).

[0041] Note that the above bond percolation is a theory, and even a gel preparation composition and a gel manufactured without completely following the bond percolation are included in the technical scope of the present invention as long as they satisfy the requirements defined in the present invention.

[0042] Therefore, according to one aspect of the present invention, there is provided a gel including a polymer prepared by crosslinking a plurality of branched monomers or branched polymers and a good solvent for the plurality of branched monomers or branched polymers, wherein the polymer in the gel is crosslinked at a concentration equal to or higher than the "overlap concentration", that is, a concentration at which the chains of adjacent branched monomers or branched polymers among the plurality of branched monomers or branched polymers overlap each other. Thereby, the branched monomers or branched polymers in the gel always overlap each other regardless of the progress of the crosslinking reaction.

[0043] The "overlap concentration" is also referred to as the "overlap concentration" as is well known to those skilled in the field of polymers, and refers to the critical concentration at which the chains of adjacent branched monomers or branched polymers begin to contact each other (that is, the regions occupied by the polymer chains overlap). Scientifically, at the overlap concentration, the local concentration (internal concentration) of the branched monomer or branched polymer is equal to the average concentration of the branched monomer or branched polymer in the entire solution.

[0044] The overlap concentration is defined as the concentration at which the zero extrapolated scattering intensity at a small angle obtained by static light scattering or small angle X-ray scattering takes a maximum value, or the concentration at which the concentration dependence of the zero shear viscosity changes from a linear relationship (viscosity ~ concentration ∧ a, a = 1) to a non-linear relationship (viscosity ~ concentration ∧ a, a > 1), which can be confirmed by experiments.

[0045] In some embodiments, the concentration of the plurality of branched monomers or polymers in the solution is preferably at least twice the overlap concentration of the plurality of branched monomers or polymers.

[0046] In a preferred embodiment, when crosslinking a functional group in a side chain or at the terminal of a branched monomer or a branched polymer with a functional group of a crosslinking agent from the viewpoint of bond percolation, the total number of functional groups reactive with the crosslinking agent in a plurality of branched monomers or branched polymers in the gel is substantially equal to the total number of functional groups of the corresponding crosslinking agent. In a specific preferred embodiment, it is preferable that the ratio of the total number of functional groups reactive with the crosslinking agent in the branched monomer or branched polymer: the total number of functional groups of the corresponding crosslinking agent is 3:2 to 2:3. Further, in a preferred embodiment, when crosslinking a nucleophilic functional group in a side chain or at the terminal of a first branched monomer or branched polymer with an electrophilic functional group in a side chain or at the terminal of a second branched monomer or branched polymer, the total number of nucleophilic functional groups in a side chain or at the terminal of the first branched monomer or branched polymer in the gel is substantially equal to the total number of functional groups reactive with the crosslinking agent of the electrophilic functional group in a side chain or at the terminal of the corresponding second branched monomer or branched polymer. In a specific preferred embodiment, it is preferable that the ratio of the total number of nucleophilic functional groups in a side chain or at the terminal of the first branched monomer or branched polymer: the total number of functional groups reactive with the crosslinking agent of the electrophilic functional group in a side chain or at the terminal of the corresponding second branched monomer or branched polymer is 3:2 to 2:3.

[0047] The concentration of the polymer prepared by crosslinking a plurality of branched monomers or branched polymers in the gel is not particularly limited, but the lower limit is preferably 1% by weight or more, preferably 6% by weight or more, preferably 6.1% by weight or more, preferably 10% by weight or more. The upper limit is preferably 99% by weight or less, preferably 70% by weight or less, preferably 50% by weight or less, preferably 40% by weight or less, preferably 30% by weight or less, preferably 20% by weight or less. In some embodiments, the concentration of the polymer in the gel is more preferably 6% by weight to 99% by weight, more preferably 10% by weight to 70% by weight, more preferably 10% by weight to 50% by weight, more preferably 10% by weight to 40% by weight, more preferably 10% by weight to 30% by weight, and even more preferably 10% by weight to 20% by weight.

[0048] The number of branches of the branched monomer or branched polymer is not particularly limited as long as it is 2 or more, but is preferably a four-branched polymer. The backbone of the branched monomer or branched polymer is not particularly limited as long as it is a chain molecule capable of constituting the branched monomer or branched polymer, but is preferably a polyethylene glycol (PEG) polymer or a polymer having a vinyl group. Examples of the polymer having a vinyl group include (meth)acrylic polymers or styrene polymers. In some preferred embodiments, the branched polymer is a four-branched polymer having a polyethylene glycol backbone or a four-branched polymer having an acrylic or styrene backbone. In the case of such polymers, a greater steric exclusion effect in the gel is achieved.

[0049] The weight average molecular weight of the branched monomer or branched polymer is not particularly limited, but examples include 1,000 to 500,000, preferably 5,000 to 100,000, and more preferably 10,000 to 50,000.

[0050] In some embodiments, the chain portions in one branched monomer or branched polymer have the same structure. For example, in the case where the branched monomer or branched polymer is a four-branched polymer, the four chain portions extending from the branches have the same structure. In the case of such polymers, a greater steric exclusion effect in the gel is achieved.

[0051] A plurality of branched monomers or branched polymers are crosslinked by crosslinking means. The crosslinking means include a combination of a functional group on the side chain or terminal of the branched monomer or branched polymer and a crosslinking agent reactive therewith, and a combination of a functional group on the side chain or terminal of the first branched monomer or branched polymer among the branched monomers or branched polymers and a functional group on the side chain or terminal of the second branched monomer or branched polymer reactive therewith. In other words, the crosslinking of the plurality of branched monomers or branched polymers may be such that adjacent branched monomers or branched polymers in the polymer are crosslinked via a crosslinking agent, or the plurality of branched monomers or branched polymers may be directly crosslinked at the side chain or terminal.

[0052] When crosslinking a plurality of branched monomers or branched polymers via a crosslinking agent, it is advantageous in that the plurality of branched monomers or branched polymers used for the production of the gel can be of one type. However, two or more types of branched monomers or branched polymers may be used.

[0053] The crosslinking agent usually has a chain-like skeleton portion containing carbon and a functional group that binds to the branched monomer or branched polymer bound to the skeleton portion. Various crosslinking agents for various polymers are well known, and those skilled in the art can select an appropriate crosslinking agent according to the type of the branched monomer or branched polymer. Those skilled in the art can easily understand an appropriate combination of the reactive group introduced into the branched monomer or branched polymer and the crosslinking agent targeting such a functional group. Preferred combinations of the functional group of the branched monomer or branched polymer and the crosslinking agent include, but are not limited to, azide-alkyne, maleimide-thiol, biotin-avidin or streptavidin, silane-silica particles, bromo-thiol, iodo-thiol, OPSS-thiol, benzophenone-nucleophilic reagent, ATFBA-nucleophilic reagent, alkyne-azide, hydrazine-amine, aldehyde-amine, acryloyl-olefin, amino-NHS ester, epoxy-amine, alcohol, or thiol, acid-amine, alcohol, or thiol, hydroxyl group-acid, etc.

[0054] The functional group of the crosslinking agent is not particularly limited as long as it is a polyfunctional crosslinking agent having bifunctionality or higher, and it may be a homopolyfunctional crosslinking agent having one type of functional group that binds to a branched monomer or a branched polymer in one crosslinking agent, or a heteropolyfunctional crosslinking agent having two or more types of functional groups that bind to a branched monomer or a branched polymer in one crosslinking agent. From the viewpoint of constituting a gel having a uniform network structure, in some preferred embodiments, the crosslinking agent is a homobifunctional crosslinking agent or a homotetrafunctional crosslinking agent.

[0055] Preferred non-limiting specific examples of the branched polymer include, for example, a compound represented by the following formula (I) having four acrylic skeletons or styrene skeletons.

[0056]

Chemical formula

[0057] In the formula, n is an integer of 1 or more. X is -COO-R 1 -CH3, -COO-R 2 -OH, or a phenyl group. Y is hydrogen or a C1-C7 alkyl group.

[0058] n is preferably 1 to 500.

[0059] R 1 is a C1-C7 alkylene group, a C2-C7 alkenylene group, -NH-R 3 -, -CO-R 4 -, -R 4 -O-R 5 -, -R 4 -NH-R 5 -, -R 4 -COO-R 5 -, -R 4 -COO-NH-R 5 -, -R 4 -CO-R 5 -, R 4 -NH-CO-R 5 - or -R 4 -CO-NH-R 5- is shown. Here, R 3 represents a C1-C7 alkylene group. R 4 represents a C1-C3 alkylene group. R 5 represents a C1-C5 alkylene group.

[0060] R 2 is a C1-C7 alkylene group, a C2-C7 alkenylene group, -NH-R 3 -, -CO-R 4 -, -R 4 -O-R 5 -, -R 4 -NH-R 5 -, -R 4 -COO-R 5 -, -R 4 -COO-NH-R 5 -, -R 4 -CO-R 5 -, R 4 -NH-CO-R 5 - or -R 4 -CO-NH-R 5 - is shown. Here, R 3 represents a C1-C7 alkylene group. R 4 represents a C1-C3 alkylene group. R 5 represents a C1-C5 alkylene group.

[0061] A is a functional group and is an azide, maleimide, bromo, iodo, alkyne, hydrazine, aldehyde, acryloyl, amino, epoxy, alcohol, or thiol, acid, or hydroxyl group. In a preferred embodiment, A is bromo.

[0062] Non-limiting examples of crosslinking agents when the branched polymer is a compound represented by formula (I) include crosslinking agents of Z-R1-(OCH2CH2) n -O-R2-Z, where n is from 1 to 500, and R1 and R2 are each independently a C1-C7 alkylene group which may be the same or different. Z is a functional group reactive with the functional group A and can be appropriately selected by those skilled in the art.

[0063] When a plurality of branched polymers are directly crosslinked at the side chains or the terminals, it is preferable to react and crosslink two types of branched polymer species as the plurality of branched polymers. The crosslinking reaction by covalent bonding of two different types of polymers is known as an AB type cross-end coupling reaction (Matsunaga et all, Macromolecules, Vol.42, No. 4, pp. 1344-1351, 2009). In some embodiments, the two types of branched polymer species are a first branched polymer having one or more nucleophilic functional groups at the side chain or the terminal, and a second branched polymer having one or more electrophilic functional groups at the side chain or the terminal. In some preferred embodiments, the two types of branched polymer species are a first branched polymer having two or more nucleophilic functional groups at the terminal, and a second branched polymer having two or more electrophilic functional groups at the terminal.

[0064] The first branched polymer and the second branched polymer are not particularly limited as long as they are chain molecules capable of constituting the branched polymer, but are preferably a polyethylene glycol (PEG) polymer or a polymer having a vinyl group. Examples of the polymer having a vinyl group include (meth)acrylic polymers or styrene polymers. In some preferred embodiments, both the first branched polymer and the second branched polymer are a four-branched polymer having a polyethylene glycol backbone or a four-branched polymer having an acrylic or styrene backbone.

[0065] The weight average molecular weights of the first and second branched polymers are not particularly limited, and examples thereof include 1000 to 500000, preferably 5000 to 100000, and more preferably 10000 to 50000.

[0066] As the combination of the nucleophilic functional group present in the first branched polymer and the electrophilic functional group present in the second branched polymer, an appropriate combination of the functional groups introduced into the branched monomer or the branched polymer as described above and the crosslinking agent targeting such functional groups can be used when crosslinking a plurality of branched monomers or branched polymers via a crosslinking agent.

[0067] In some embodiments, examples of the nucleophilic functional group present in the first branched polymer include a thiol group (-SH), an amino group, or -COOPhNO2 (where Ph represents an o-, m-, or p-phenylene group), and those skilled in the art can appropriately use known nucleophilic functional groups. Preferably, the nucleophilic functional group is an -SH group. The nucleophilic functional groups may be the same or different from each other, but it is preferable that they are the same. When the functional groups are the same, the reactivity with the electrophilic functional group that forms the crosslinking bond becomes uniform, and it becomes easier to obtain a gel having a uniform three-dimensional structure.

[0068] In some embodiments, an active ester group can be used as the electrophilic functional group present in the second branched polymer. Examples of such active ester groups include a maleimidyl group, an N-hydroxy-succinimidyl (NHS) group, a sulfosuccinimidyl group, a phthalimidyl group, an imidazolyl group, an acryloyl group, or a nitrophenyl group, and those skilled in the art can appropriately use other known active ester groups. Preferably, the electrophilic functional group is a maleimidyl group. The electrophilic functional groups may be the same or different from each other, but it is preferable that they are the same. When the functional groups are the same, the reactivity with the nucleophilic functional group that forms the crosslinking bond becomes uniform, and it becomes easier to obtain a gel having a uniform three-dimensional structure.

[0069] Suitable combinations of the first branched polymer and the second branched polymer are also described in JP 2018-116043.

[0070] Preferable non-limiting specific examples of the first branched polymer include, for example, a compound represented by the following formula (II) having four branches of a polyethylene glycol backbone.

[0071]

Chemical formula

[0072] n 11 ~n14 may be the same or different from each other. n 11 ~n 14 The closer the values of n~n are, the more uniform the three-dimensional structure can be and the higher the strength will be. Therefore, for obtaining a high-strength gel, it is preferably the same. n 11 ~n 14 If the value of n~n is too high, the strength of the gel will become weak, n 11 ~n 14 If the value of n~n is too low, it is difficult to form a gel due to the steric hindrance of the compound. Therefore, n 11 ~n 14 n is an integer value of 25 to 250, preferably 35 to 180, more preferably 50 to 115, and particularly preferably 50 to 60. And the weight-average molecular weight of the first branched polymer is, for example, 5000 to 50000, preferably 7500 to 30000, and more preferably 10000 to 20000.

[0073] From the point of making the structure of the gel uniform, the concentration of the first branched polymer in the gel is preferably 3% by weight to 49% by weight, more preferably 5% by weight to 35% by weight, more preferably 5% by weight to 30% by weight, more preferably 5% by weight to 25% by weight, more preferably 5% by weight to 20% by weight, more preferably 5% by weight to 15% by weight, and more preferably 5% by weight to 10% by weight.

[0074] B is a nucleophilic functional group, and is a thiol group (-SH), an amino group, or -COOPhNO2 (Ph represents an o-, m-, or p-phenylene group).

[0075] In the above formula (II), R 11 ~R 14 is a linker moiety connecting the nucleophilic functional group and the core moiety.

[0076] R 11 ~R 14 may be the same or different from each other, but for producing a high-strength gel having a uniform three-dimensional structure, it is preferably the same. R 11 ~R 14 is a C1-C7 alkylene group, a C2-C7 alkenylene group, -NH-R 15-、 -CO-R 15 -、 -R 16 -O-R 17 -、 -R 16 -NH-R 17 -、 -R 16 -COO-R 17 -、 -R 16 -COO-NH-R 17 -、 -R 16 -CO-R 17 -、 R 16 -NH-CO-R 17 - or -R 16 -CO-NH-R 17 - represents. Here, R 15 represents a C1-C7 alkylene group. R 16 represents a C1-C3 alkylene group. R 17 represents a C1-C5 alkylene group.

[0077] Here, the "C1-C7 alkylene group" means an alkylene group having 1 to 7 carbon atoms which may have a branch, and means a straight-chain C1-C7 alkylene group or a C2-C7 alkylene group having one or two or more branches (the number of carbon atoms including the branch is 2 or more and 7 or less). Examples of the C1-C7 alkylene group are a methylene group, an ethylene group, a propylene group, and a butylene group.

[0078] Examples of the C1-C7 alkylene group include -CH2-, -(CH2)2-, -(CH2)3-, -CH(CH3)-, -(CH2)3-, -(CH(CH3))2-, -(CH2)2-CH(CH3)-, -(CH2)3-CH(CH3)-, -(CH2)2-CH(C2H5)-, -(CH2)6-, -(CH2)2-C(C2H5)2-, and -(CH2)3C(CH3)2CH2-.

[0079] The "C2-C7 alkenylene group" is a linear or branched alkenylene group having 2 to 7 carbon atoms and having one or two or more double bonds in the chain. For example, a divalent group having a double bond formed by removing 2 to 5 hydrogen atoms of adjacent carbon atoms from the above-mentioned alkylene group can be mentioned.

[0080] On the one hand, non-limiting specific examples of a polymer unit having an electrophilic functional group at the end include, for example, a compound represented by the following formula (III) having four polyethylene glycol backbone branches.

[0081]

Chemical formula

[0082] In the above formula (III), n 21 ~n 24 may be the same or different from each other. The closer the values of n 21 ~n 24 are to each other, the more likely the gel can take on a uniform three-dimensional structure and the higher the strength, so it is preferable, and it is more preferable that they are the same. If the values of n 21 ~n 24 are too high, the strength of the gel will be weak, and if the values of n 21 ~n 24 are too low, it is difficult to form a gel due to steric hindrance of the compound. Therefore, n 21 ~n 24 is an integer value of 5 to 30, preferably 20 to 250, more preferably 30 to 180, even more preferably 45 to 115, and even more preferably 45 to 55. The weight average molecular weight of the second branched polymer is, for example, 5000 to 50000, preferably 7500 to 30000, and more preferably 10000 to 20000.

[0083] From the point of making the structure of the gel uniform, the concentration of the second branched polymer in the gel is preferably 3% by weight to 49% by weight, more preferably 5% by weight to 35% by weight, more preferably 5% by weight to 30% by weight, more preferably 5% by weight to 25% by weight, more preferably 5% by weight to 20% by weight, more preferably 5% by weight to 15% by weight, and more preferably 5% by weight to 10% by weight.

[0084] D is an electrophilic functional group and is a maleimidyl group, an N-hydroxy-succinimidyl (NHS) group, a sulfosuccinimidyl group, a phthalimidyl group, an imidazolyl group, an acryloyl group or a nitrophenyl group.

[0085] In the above formula (III), R 21 ~R 24 is a linker moiety that connects the electrophilic functional group and the core moiety. R 21 ~R 24 may be the same or different from each other, but are preferably the same in order to produce a high-strength gel having a uniform three-dimensional structure. In formula (III), R 21 ~R 24 are each the same or different and are a C1-C7 alkylene group, a C2-C7 alkenylene group, -NH-R 25 -, -CO-R 25 -, -R 26 -O-R 27 -, -R 26 -NH-R 27 -, -R 26 -COO-R 27 -, -R 26 -COO-NH-R 27 -, -R 26 -CO-R 27 -, -R 26 -NH-CO-R 27 -, or -R 26 -CO-NH-R 27 -. Here, R 25 represents a C1-C7 alkylene group. R 26 represents a C1-C3 alkylene group. R 27 represents a C1-C5 alkylene group.

[0086] In the present specification, the alkylene group and the alkenylene group may each have one or more arbitrary substituents. Examples of the substituent include, but are not limited to, an alkoxy group, a halogen atom (which may be any of a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom), an amino group, a mono- or di-substituted amino group, a substituted silyl group, an acyl group, or an aryl group. When the alkyl group has two or more substituents, they may be the same or different. The same applies to the alkyl moiety of other substituents containing an alkyl moiety (such as an alkyloxy group or an aralkyl group).

[0087] In the method for producing the gel of the present invention, the first branched polymer and the second branched polymer may be mixed at a molar ratio of 0.5:1 to 1.5:1.

[0088] In some embodiments, the plurality of branched monomers or branched polymers, excluding the plurality of branched polymers, are branched polymers synthesized by an AB-type cross-end coupling reaction, which is a cross-linking reaction by covalent bonding of two different types of polymers for each branched polymer. In some embodiments, the plurality of branched monomers or branched polymers, excluding the plurality of branched polymers, are branched polymers synthesized by cross-linking a first branched polymer having one or more nucleophilic functional groups in the side chain or at the end and a second branched polymer having one or more electrophilic functional groups in the side chain or at the end. Here, the branched polymer is a four-branched polymer having a polyethylene glycol backbone. In some preferred embodiments, the plurality of branched monomers or branched polymers, excluding the plurality of branched polymers, are branched polymers synthesized by cross-linking a first branched polymer having two or more nucleophilic functional groups at the end and a second branched polymer having two or more electrophilic functional groups at the end. Here, the branched polymer is a four-branched polymer having a polyethylene glycol backbone.

[0089] In some embodiments, the polymer prepared by cross-linking the plurality of branched monomers or branched polymers excludes a polymer in which a first four-branched polymer and a second four-branched polymer different from the first four-branched polymer are cross-linked via a cross-linking agent or directly cross-linked.

[0090] The good solvent is not particularly limited as long as it has a high solubility for a plurality of branched monomers or branched polymers. However, when producing the gel of one embodiment of the present invention, it is preferably a solvent that assists the overlapping of the branched chain portions (arms) of adjacent branched monomers or branched polymers among the plurality of branched monomers or branched polymers constituting the gel. The good solvent may be water or an organic solvent. Examples of the organic solvent include anhydrous acetonitrile, acetone, N,N-dimethylformamide, methanol, ethanol, and the like. When the branched monomer or branched polymer has a higher solubility in an organic solvent than in water, the good solvent is preferably an organic solvent. For example, when the branched monomer or branched polymer is a 4-branched PEG polymer, the good solvent is preferably anhydrous acetonitrile. An appropriate good solvent can be appropriately selected according to the type of the branched monomer or branched polymer. For example, in dynamic light scattering measurement, when a composition containing a plurality of branched monomers or branched polymers and a good solvent for the branched monomer or branched polymer is measured at a scattering angle of 90°, if only either the diffusion mode or the cooperative diffusion mode of the branched monomer or branched polymer is observed and no relaxation mode indicating an aggregate is observed, such a good solvent can be determined to be suitable for the production of the gel of the present invention.

[0091] The concentration of the good solvent in the gel is not particularly limited, but the lower limit is preferably 1% by weight or more, preferably 30% by weight or more, preferably 50% by weight or more, preferably 60% by weight or more, preferably 70% by weight or more, preferably 80% by weight or more. The upper limit is preferably 93.9% by weight or less, preferably 90% by weight or less. In some embodiments, the concentration of the good solvent in the gel is preferably 1% by weight to 93.9% by weight, more preferably 30% by weight to 90% by weight, more preferably 50% by weight to 90% by weight, more preferably 60% by weight to 90% by weight, more preferably 70% by weight to 90% by weight, more preferably 80% by weight to 90% by weight.

[0092] In some embodiments, the gel may consist only of a polymer prepared by crosslinking a plurality of branched monomers or branched polymers and a good solvent for the plurality of branched monomers or branched polymers. In another embodiment, the gel of the present invention may contain one or more additives in addition to a polymer prepared by crosslinking a plurality of branched monomers or branched polymers and a good solvent for the plurality of branched monomers or branched polymers. Such additives include active ingredients of pharmaceuticals or cosmetics, buffers, isotonic agents, preservatives, antioxidants, excipients, carriers, diluents, solvents other than good solvents, solubilizers, stabilizers, fillers, binders, surfactants, adhesives, stabilizers, thermosensitive agents, fragrances, salts, antioxidants, chelating agents, neutralizing agents, pH adjusters, and the like.

[0093] In some embodiments, the gel of the present invention has the same type and concentration in the gel of the polymer prepared by crosslinking a plurality of branched monomers or branched polymers, and the same type and concentration in the gel of the good solvent. Using a polymer solution corresponding to the composition before crosslinking of the gel as a comparative polymer solution, when comparing the comparative polymer solution with the gel, the small angle X-ray scattering spectrum (SAXS) between the uncrosslinked polymer solution and the gel -1 The maximum change rate of the scattering intensity I(q) below is within the range of -50% to +100%, and / or 0.005 Å in the profile of the static laser light scattering (SLS) between the uncrosslinked polymer solution and the gel -1 The maximum change rate of the scattering intensity I(q) below is within the range of -50% to +100%. That is, when comparing the solution before crosslinking and the gel after crosslinking having the same composition, the change rates of I(q) of the gels are small with respect to each other. The change rate of the scattering intensity I(q) between the uncrosslinked polymer solution and the gel refers to the value represented by (I2(q) - I1(q)) / I1(q) × 100 (%) where I(q) of the uncrosslinked polymer solution is I1(q) and I(q) of the gel is I2(q).

[0094] In this specification, the scattering intensity I(q) with respect to the scattering vector q in SLS and SAXS can be determined by the method described in the examples. In a preferred embodiment, in SLS, 7x10 -4 Å -1 < q < 2x10 -3 Å -1 range, and in SAXS, 1x10 -2 < q < 1x10 -1 Å -1 range are measured. The beam irradiation volume on the gel specimen is desirably 0.3 mm 3 or more.

[0095] q is the magnitude of the scattering vector, and the scattering intensity I(q) can be measured using a commercially available light scattering device. In this specification, a He-Ne laser (wavelength λ = 632.8 nm) is used as the incident light source, and the scattered light is collected with a single-pixel avalanche photodiode detector mounted on a goniometer at a scattering angle of 2θ, in the range of 30° to 150°, and an exposure time of 30 seconds for each angle. The scattering intensity I(q) is plotted as a function of the magnitude of the scattering vector q = 4πn sinθ / λ (where n is the refractive index of the solvent). In conventional polymer gels, the scattering intensity I(q) measured by SLS and / or SAXS rapidly increases in the low region (long-range correlation) of the scattering vector q (see also Figure 3, T. Sakai, Macromolecules 41, 5379-5384 (2008); T. Matsunaga, et al, Macromolecules 42, 6245-6252 (2009)), which means that the scattering becomes stronger and reflects the manifestation of the spatial inhomogeneity of the cross-linked structure of the polymer.

[0096] In some embodiments, in SLS, 7x10 -4 Å -1 < q < 2x10 -3 Å -1 range, and in SAXS, 1x10 -2 < q < 1x10 -1 Å -1Within the range, the increase rate of the scattering intensity I(q) in the direction where the scattering vector q in SAXS / SLS in the gel decreases substantially does not change. Preferably, the maximum change rate of the scattering intensity I(q) within the above range is within the range of -50% to +100%. This indicates that little or no light scattering due to structural inhomogeneity in the gel occurs. The gel of such an embodiment of the present invention has little change in the scattering intensity I(q) in the low region of the scattering vector q measured by SAXS and / or SLS, and the polymer cross-linked structure of the gel is more orderly and spatially uniform.

[0097] In some embodiments, the change rate of the time correlation function g2 of the gel over the range of the delay time τ of 0.001 to 0.1 (ms) from the time correlation function at the gelation point to the time correlation function 10 times the time required for gelation is within ±10%. The change rate of the time correlation function g2 is defined as (g 2a - g 2b ) / g 2b * 100 (%) when the time correlation function at the gelation point is g 2a and the time correlation function 10 times the time required for gelation is g 2a .

[0098] The gel of such an embodiment of the present invention has a stable and orderly structure of the gel material such that little scattering caused by spatial inhomogeneity occurs even as time passes, achieving an ultimate uniformity that could not be achieved with conventional gels.

[0099] In some embodiments, the difference in the time correlation functions at two or more different positions over a gel delay time range of 0.001 to 0.1 (ms) is within ±10%. In another embodiment, the difference between the ensemble-averaged time correlation function over a gel delay time range of 0.001 to 0.1 (ms) and the time correlation functions at each of 100 different positions of a gel cut out to a height of 20 mm and a diameter of 8 mm is within ±10%. In yet another embodiment, the difference between the time correlation functions at each of 100 different positions of a gel cut out to a height of 20 mm and a diameter of 8 mm over a gel delay time range of 0.001 to 0.1 (ms) is within ±10%.

[0100] The gel of such an embodiment of the present invention has a structure in which the gel material is ordered and stable to such an extent that almost no scattering caused by spatial non-uniformity occurs regardless of the measurement position of the gel even over time, achieving an ultimate uniformity that could not be achieved with conventional gels.

[0101] In this specification, the time correlation function g2 of the scattering intensity is defined by the following equation (S4).

[0102]

Equation

[0103] In the formula, I(t) is the scattering intensity at time t, τ is the delay time, <...> T is the time average.

[0104] In this specification, the ensemble-averaged time correlation function is defined by the following equation (S5).

[0105]

Equation

[0106] In the formula, I(t) is the scattering intensity at time t, τ is the delay time, <...> E is the ensemble average.

[0107] By substituting (S4) into (S5), the relationship between the time correlation function and its ensemble average quantity can be obtained (see H. Furukawa et al., J. Phys. Soc. Jpn. 71, 2873-2880 (2002)).

[0108]

Number

[0109] In some embodiments, the gel of the present invention has a highly ordered network structure because it has few or no spatial defects.

[0110] In some embodiments, the gel of the present invention is a transparent gel. Preferably, the light transmittance of the gel is 95% or more. The light transmittance of the gel can be measured under the condition of subtracting the influence of the transmittance of the solvent contained in the gel using an optical quartz cell with an optical path length of 1 cm between wavelengths of 450 - 800 nm. However, absorption derived from branched monomers or branched polymers is excluded from the calculation of the transmittance.

[0111] The gel of the present invention can be produced by curing a gel preparation composition containing a plurality of branched monomers or branched polymers before crosslinking and a good solvent by crosslinking. Further, by putting the gel preparation composition into a mold and curing it, it can be molded into a desired shape such as a sheet shape or a spherical shape according to the intended purpose. The shape of the gel sheet, which is a sheet-shaped gel, can be arbitrarily shaped according to the intended purpose, and examples include, but are not limited to, a substantially rectangular shape or a substantially circular shape in plan view.

[0112] In some embodiments of the present invention, a porous polymer crosslinked body obtained by reducing or removing a good solvent from the gel of the embodiment of the present invention is provided. Reduction or removal of the good solvent can be performed by a conventional method in the art such as heating and drying or air drying. Such a porous polymer crosslinked body is advantageous in that the order of the polymer structure is high.

[0113] According to another aspect of the present invention, there is provided a composition comprising a plurality of branched monomers or branched polymers and a good solvent for the branched monomers or branched polymers, wherein the plurality of branched monomers or branched polymers are arranged in the good solvent at a concentration equal to or higher than the concentration at which the chains of adjacent branched monomers or branched polymers overlap. Such a composition can be used for the preparation of the gel of one aspect of the present invention described above.

[0114] In a preferred embodiment, from the viewpoint of bond percolation, when crosslinking a functional group on a side chain or terminal of a plurality of branched monomers or branched polymers with a functional group of a crosslinking agent, the total number of functional groups reactive with the crosslinking agent in the plurality of branched monomers or branched polymers and the total number of functional groups of the corresponding crosslinking agent are substantially equal. In a specific preferred embodiment, the ratio of the total number of functional groups reactive with the crosslinking agent in the branched monomer or branched polymer: the total number of functional groups of the corresponding crosslinking agent is preferably from 3:2 to 2:3.

[0115] Also, in a preferred embodiment, when crosslinking a nucleophilic functional group on a side chain or terminal of a first branched monomer or branched polymer with an electrophilic functional group on a side chain or terminal of a second branched monomer or branched polymer, the total number of nucleophilic functional groups on a side chain or terminal of the first branched monomer or branched polymer and the total number of functional groups reactive with the crosslinking agent of the electrophilic functional group on a side chain or terminal of the corresponding second branched monomer or branched polymer are substantially equal. In a specific preferred embodiment, the ratio of the total number of nucleophilic functional groups on a side chain or terminal of the first branched monomer or branched polymer: the total number of functional groups reactive with the crosslinking agent of the electrophilic functional group on a side chain or terminal of the corresponding second branched monomer or branched polymer is preferably from 3:2 to 2:3.

[0116] The concentration of the polymer prepared by crosslinking a plurality of branched monomers or branched polymers is not particularly limited, but the lower limit is preferably 1% by weight or more, preferably 6% by weight or more, preferably 6.1% by weight or more, preferably 10% by weight or more. The upper limit is preferably 99% by weight or less, preferably 70% by weight or less, preferably 50% by weight or less, preferably 40% by weight or less, preferably 30% by weight or less, preferably 20% by weight or less. In some embodiments, the concentration of the polymer in the gel is more preferably 6% to 99% by weight, more preferably 10% to 70% by weight, more preferably 10% to 50% by weight, more preferably 10% to 40% by weight, more preferably 10% to 30% by weight, and even more preferably 10% to 20% by weight.

[0117] Details of the branched monomer or branched polymer, good solvent, and crosslinking means are as described above for the gel of one aspect of the present invention.

[0118] The number of branches of the branched monomer or branched polymer is not particularly limited as long as it is 2 or more, but is preferably a four-branched polymer. The skeleton of the branched monomer or branched polymer is not particularly limited as long as it is a chain molecule capable of constituting the branched monomer or branched polymer, but is preferably a polyethylene glycol (PEG) polymer or a polymer having a vinyl group. Examples of the polymer having a vinyl group include (meth)acrylic polymers or styrene polymers. In some preferred embodiments, the branched monomer or branched polymer is a four-branched polymer having a polyethylene glycol skeleton or a four-branched polymer having an acrylic or styrene skeleton. In the case of such a polymer, a greater steric exclusion effect in the gel is achieved.

[0119] In some preferred embodiments, the chain portions in a single branched monomer or branched polymer have the same structure. For example, in the case of a four-branched polymer, the four chain portions extending from the branches have the same structure. In the case of such a polymer, a greater steric exclusion effect in the gel is achieved.

[0120] A plurality of branched monomers or branched polymers are crosslinked by crosslinking means, and the crosslinking means include a combination of a functional group on the side chain or terminal of the branched monomer or branched polymer and a crosslinking agent reactive therewith, and a combination of a functional group on the side chain or terminal of the first branched monomer or branched polymer among the branched monomers or branched polymers and a functional group on the side chain or terminal of the second branched monomer or branched polymer reactive therewith. In other words, the crosslinking of a plurality of branched monomers or branched polymers may be such that adjacent branched monomers or branched polymers in the polymer are crosslinked via a crosslinking agent, or a plurality of branched monomers or branched polymers may be directly crosslinked at the side chain or terminal.

[0121] In some embodiments, the composition of the present invention has a maximum change rate of the scattering intensity I(q) in the range of -50% to +100% in the range of the scattering vector 1x10 -2 < q < 1x10 -1 Å -1 in the profile of the small-angle X-ray scattering spectrum (SAXS) between the uncrosslinked composition and the gel after crosslinking the composition.

[0122] In some embodiments, the composition of the present invention has a maximum change rate of the scattering intensity I(q) in the range of -50% to +100% in the range of the scattering vector q of 7x10 -4 Å -1 < q < 2x10 -3 Å -1 in the profile of the static laser light scattering (SLS) between the uncrosslinked composition and the gel after crosslinking the composition.

[0123] In some embodiments, at 7x10 -4 Å -1< q < 2 x 10 -3 Å -1 In the range of -2 , where 1 x 10 -2 < q < 1 x 10 -1 Å -1 In this range, the rate of increase of the scattering intensity I(q) in the direction in which the scattering vector q in SAXS / SLS in the composition decreases is substantially unchanged. Preferably, the maximum rate of change of the scattering intensity I(q) in the above range is within the range of -50% to +100%. This indicates that little or no light scattering due to structural inhomogeneity in the composition occurs. The composition of such an embodiment of the present invention has little change in the scattering intensity I(q) in the low region of the scattering vector q measured by SAXS and / or SLS and is spatially uniform.

[0124] In some embodiments, the rate of change of the time correlation function g2 of the composition after gelation with respect to the composition before gelation of the composition is within ±10% over a range of delay times from 0.001 to 0.1 (ms). The rate of change of the time correlation function g2 is the time correlation function before gelation is g 2c , and the time correlation function after gelation is g 2d When, (g 2d - g 2c ) / g 2c *100 (%).

[0125] The composition of such an embodiment of the present invention has a structure that is so orderly and stable that little scattering due to spatial inhomogeneity occurs even when changing from a sol state to a gel state, achieving an ultimate uniformity that could not be achieved with conventional compositions for gel preparation.

[0126] According to another aspect of the present invention, there is provided a method for producing a gel containing a polymer prepared by polymerizing a plurality of branched monomers or branched polymers, the method including mixing a plurality of branched monomers or branched polymers in a good solvent at a concentration equal to or higher than the concentration at which the chains of adjacent branched monomers or branched polymers among the plurality of branched monomers or branched polymers overlap, and polymerizing the plurality of branched monomers or branched polymers to obtain a gel.

[0127] Such a gel can be obtained by polymerizing the above composition of one embodiment of the present invention. The structure and amount of the branching monomer or polymer in the composition, the structure and amount of the good solvent in the composition, and the details of the crosslinking means are as described above.

[0128] In some embodiments, the method for producing the gel of the present invention further includes adding a crosslinking agent before polymerizing the plurality of branching monomers or polymers.

[0129] In some embodiments, polymerizing the plurality of branching monomers or polymers includes crosslinking the plurality of branching monomers or polymers by a stimulus. The stimulus includes, but is not limited to, one or more selected from the group consisting of heat·temperature, pH, magnetism, vibration, humidity, water, electromagnetic waves, light, electricity, and pressure. For example, when a functional group on the side chain or end of the branching monomer or polymer crosslinks with a reactive crosslinking agent, or when a functional group on the side chain or end of the first branching monomer or polymer among the branching monomers or polymers crosslinks with a functional group on the side chain or end of the second branching monomer or polymer that is reactive thereto, the crosslinking reaction can be promoted by heating. Those skilled in the art can select an appropriate stimulus for the purpose of maintaining the uniform structure of the resulting gel.

[0130] In some embodiments, the method for producing the gel of the present invention further includes a step of purifying a mixed solution containing the plurality of branching monomers or polymers and the good solvent before polymerizing the plurality of branching monomers or polymers. The purification can be performed by filtration using a filter or a membrane, adsorption, or the like. Such a purification step can produce a gel with higher purity, higher order, and greater uniformity.

[0131] The gel obtained by the method for producing a gel of the present invention may satisfy the range described for the gel of one aspect of the present invention in at least any one of the scattering intensity I(q) of SAXS and / or the scattering intensity I(q) of SLS, the rate of change of the time correlation function after gelation compared to before gelation, and the difference in the time correlation function at two or more different positions.

[0132] The method for producing a gel material based on bond percolation proposed in the present application does not depend on the chemical species or reaction mode of the branched monomer or branched polymer. Therefore, the gels, gel sheets, and porous polymer crosslinked bodies of the above-described embodiments of the present invention may be applicable to various crosslinked polymer materials, and a wide range of fields such as medicine, pharmacy, chemistry, engineering, and electronics are expected to have a ripple effect.

[0133] Since the gels, gel sheets, and porous polymer crosslinked bodies of the above-described embodiments of the present invention have a uniform network structure with a highly ordered network, abnormal scattering of light due to structural inhomogeneity does not occur, and thus it is possible to realize the theoretical upper limit of transparency that can be achieved as a soft material. For this reason, for example, the gels, gel sheets, and porous polymer crosslinked bodies of the embodiments of the present invention can be used as components of cosmetics, pharmaceuticals, quasi-drugs, medical products, additives, paints, ink bases, absorbents, sustained-release agents, carriers, glass substitutes, adhesives, pressure-sensitive adhesives, heat insulators, sound absorbers, shock absorbers, load dispersants, electrode materials, optical fibers, films, fillers, fillers, filters, separation membranes, or electrode materials, but can be used for a wide range of applications not limited thereto. In addition, the present invention can also adopt the following configuration.

[0134] Item 1. A gel containing a polymer prepared by crosslinking a plurality of branched monomers or branched polymers and a good solvent for the plurality of branched monomers or branched polymers, wherein the polymer in the gel is crosslinked at a concentration equal to or higher than the concentration at which the chains of adjacent branched monomers or branched polymers among the plurality of branched monomers or branched polymers overlap each other.

[0135] Item 2. When compared with a polymer solution corresponding to the composition before crosslinking of a gel in which the types and concentrations in the gel of the polymer prepared by crosslinking the plurality of branched monomers or branched polymers are the same, and the types and concentrations in the gel of the good solvent are the same, the maximum change rate of the scattering intensity I(q) at 0.1 Å -1 in the following is in the range of -50% to +100%, and / or the maximum change rate of the scattering intensity I(q) at 0.005 Å -1 in the following is in the range of -50% to +100%. The gel according to Item 1.

[0136] Item 3. The gel according to Item 1 or 2, containing the polymer in the range of 6% by weight to 99% by weight.

[0137] Item 4. The gel according to any one of Items 1 to 3, wherein adjacent branched monomers or branched polymers in the polymer are crosslinked via a crosslinking agent or directly crosslinked.

[0138] Item 5. The gel according to any one of Items 1 to 4, wherein the change rate from the time correlation function at the gelation point of the gel over a delay time range of 0.001 to 0.1 (ms) to the time correlation function 10 times the time required for gelation is within ±10%.

[0139] Item 6. The scattering vector in the profile of the small-angle X-ray scattering spectrum (SAXS) between the uncrosslinked polymer solution and the gel is 1x10 -2 < q < 1x10 -1 Å -1 and the maximum change rate of the scattering intensity I(q) in the range is in the range of -50% to +100%. The gel according to Item 2.

[0140] Item 7. The scattering vector q in the profile of the static laser light scattering (SLS) between the uncrosslinked polymer solution and the gel is 7x10 -4 Å -1< q < 2x10 -3 Å -1 The gel according to item 2, wherein the maximum change rate of the scattering intensity I(q) in the range of -3 Å to -1 Å is within the range of -50% to +100%.

[0141] Item 8. The gel according to any one of items 1 to 7, wherein the difference in the time correlation function at two or more different positions over the range of the delay time of the gel from 0.001 to 0.1 (ms) is within ±10%.

[0142] Item 9. The gel according to any one of items 1 to 8, wherein the light transmittance is 95% or more.

[0143] Item 10. A composition comprising a plurality of branched monomers or branched polymers and a good solvent for the branched monomers or branched polymers, wherein the plurality of branched monomers or branched polymers are arranged in the good solvent at a concentration equal to or higher than the concentration at which the chains of adjacent branched monomers or branched polymers overlap.

[0144] Item 11. The composition according to item 10, further comprising a crosslinking agent for crosslinking the branched monomers or branched polymers.

[0145] Item 12. The composition according to item 10, wherein the plurality of branched monomers or branched polymers include a first branched monomer or branched polymer having a nucleophilic functional group and a second branched monomer or branched polymer having an electrophilic functional group reactive with the nucleophilic functional group.

[0146] Item 13. The composition according to any one of items 10 to 12, wherein the change rate of the time correlation function of the composition after gelation with respect to the composition before gelation over the range of the delay time from 0.001 to 0.1 (ms) is within ±10%.

[0147] Item 14. A method for producing a gel containing a polymer prepared by polymerizing a plurality of branched monomers or branched polymers, comprising mixing a plurality of branched monomers or branched polymers in a good solvent at a concentration equal to or higher than the concentration at which the chains of adjacent branched monomers or branched polymers overlap among the plurality of branched monomers or branched polymers, and Polymerizing the plurality of branched monomers or branched polymers to obtain a gel, A method comprising.

[0148] Item 15. The production method according to item 14, further comprising adding a crosslinking agent before polymerizing the plurality of branched monomers or branched polymers.

[0149] Item 16. Polymerizing the plurality of branched monomers or branched polymers includes crosslinking the plurality of branched monomers or branched polymers by one or more stimuli selected from the group consisting of heat, temperature, pH, gas, magnetism, vibration, humidity, water, electromagnetic waves, light, electricity, and pressure. The production method according to item 14 or 15.

[0150] Item 17. The production method according to any one of items 14 to 16, further comprising a step of purifying a mixed solution containing the plurality of branched monomers or branched polymers and the good solvent before polymerizing the plurality of branched monomers or branched polymers.

[0151] Item 18. When the produced gel is compared with a polymer solution corresponding to the composition before crosslinking of the gel, in which the types of polymers prepared by crosslinking the plurality of branched monomers or branched polymers and the concentration in the gel are the same, and the types of good solvents and the concentration in the gel are the same, the maximum change rate of the scattering intensity I(q) at 0.1 Å in the small-angle X-ray scattering spectrum (SAXS) profile between the uncrosslinked polymer solution and the gel is in the range of -50% to +100%, and / or the maximum change rate of the scattering intensity I(q) at 0.005 Å in the profile of static laser light scattering (SLS) between the uncrosslinked polymer solution and the gel is in the range of -50% to +100%. The production method according to any one of items 14 to 17. -1 The maximum change rate of the scattering intensity I(q) below is in the range of -50% to +100%, and / or the maximum change rate of the scattering intensity I(q) at 0.005 Å in the profile of static laser light scattering (SLS) between the uncrosslinked polymer solution and the gel is in the range of -50% to +100%. -1 The production method according to any one of items 14 to 17.

[0152] Item 19. A gel sheet containing the gel according to any one of items 1 to 9.

[0153] Item 20. A porous polymer crosslinked body obtained by reducing or removing the good solvent from the gel according to any one of Items 1 to 9.

[0154] Item 21. A cosmetic, pharmaceutical, quasi-drug, medical product, additive, paint, ink base, absorbent, sustained-release agent, carrier, glass substitute, adhesive, pressure-sensitive adhesive, heat insulating material, sound absorbing material, shock absorbing material, load dispersing material, electrode material, optical fiber, film, filler, filling agent, filter, separation membrane or electrode material containing the gel according to any one of Items 1 to 9, the gel sheet according to Item 19, or the porous polymer crosslinked body according to Item 20.

[0155] Item 22. Use of the gel according to any one of Items 1 to 9, the gel sheet according to Item 19, or the porous polymer crosslinked body according to Item 20 for the production of a cosmetic, pharmaceutical, quasi-drug, medical product, additive, paint, ink base, absorbent, sustained-release agent, carrier, glass substitute, adhesive, pressure-sensitive adhesive, heat insulating material, sound absorbing material, shock absorbing material, load dispersing material, electrode material, optical fiber, film, filler, filling agent, filter, separation membrane or electrode material.

[0156] Item 23. The gel according to any one of Items 1 to 9, wherein the plurality of branched monomers or branched polymers are a four-branched polymer having a polyethylene glycol backbone or a four-branched polymer having an acrylic or styrene backbone.

[0157] Item 24. The gel according to any one of Items 1 to 9, wherein the plurality of branched monomers or branched polymers are only one type of four-branched polymer.

[0158] Item 25. The gel according to any one of Items 1 to 9, excluding the plurality of branched polymers, wherein the plurality of branched monomers or branched polymers are a four-branched polymer having a polyethylene glycol backbone, which is synthesized by crosslinking a first branched polymer having two or more nucleophilic functional groups at the terminal and a second branched polymer having two or more electrophilic functional groups at the terminal.

[0159] Examples Examples are given below to explain the present invention more specifically, but the present invention is not limited thereto. Unless otherwise specified, the experiments were carried out at a temperature of 25°C and a pressure of 1 bar (10 5 Pa).

[0160] Test Example 1 Materials and Methods 1. Preparation of Star Polymer Gel A 4-functional poly(ethylene glycol) (tetra-PEG-NHS; Mw = 20 kg mol -1 , NOF) with N-hydroxysuccinimidyl ester at the end and 1,14-diamino-3,6,9,12-tetraoxatetradecane (amino-PEG4-amine; Sigma-Aldrich) were separately dissolved in anhydrous acetonitrile containing 100 mM acetic acid. Solutions of tetra-PEG-NHS (6 mM) and amino-PEG4-amine (12 mM) were mixed using a centrifugal mixer (AR-100, THINKY). The molar concentration of amino-PEG4-amine was set to be twice that of tetra-PEG-NHS so that the molar concentration of the amine matched that of the NHS group. The mixed solution was immediately filtered through a fine syringe filter with a 20 nm pore size (FD5AXFR12, Entegris), placed in a clean glass tube with a diameter of 10 mm, and then sealed with paraffin. An acid was added to acetonitrile to adjust the reaction rate between the NHS and amine groups so that the gelation point was about 1 hour after mixing tetra-PEG-NHS and amino-PEG4-amine. All preparation procedures were carried out at room temperature (about 25°C). Note that anhydrous acetonitrile was selected as a good solvent because only one relaxation was observed when a solution of tetra-PEG-NHS dissolved in anhydrous acetonitrile was measured by time-resolved DLS described below (Figure 4).

[0161] 2. Preparation of Conventional Gel Using NIPAM as a Monomer NIPAM (4 mmol) and N,N′-methylenebis(acrylamide) (BIS; 0.08 mmol) were dissolved in 10 ml of water. Argon gas was dispersed in the NIPAM / BIS solution for 20 minutes to remove oxygen from the solution. Next, ammonium persulfate (0.008 mmol) and N,N,N′,N′-tetramethyl-ethylenediamine (0.04 mmol) were added to the solution. The mixed solution was filtered through a fine syringe filter with a 20 nm pore size (FD5AXFR12, Entegris), placed in a clean glass tube with a diameter of 10 mm, and then sealed with paraffin. All preparation procedures were carried out at 25°C.

[0162] 3. Dynamic Viscoelasticity Measurement The dynamic viscoelasticity measurement of the gelation process of the star polymer was carried out using a rheometer (MCR 501, Anton-Paar). The temperature, shear strain, and shear frequency were 25°C, 2%, and 1 Hz, respectively. The storage modulus G' and the loss modulus G" were measured according to H. H. Winter et al, J. Rheol. 30, 367 - 382 (1986).

[0163] 4. 1-Dimensional Static Light Scattering Static light scattering (SLS) was performed using a commercially available light scattering instrument (ALV-5000, ALV) with a He-Ne laser (wavelength λ = 632.8 nm) as the incident light source. The scattered light was collected by a single-pixel avalanche photodiode detector mounted on a goniometer at a scattering angle of 2θ, in the range of 30° to 150°, with an exposure time of 30 seconds for each angle. The scattered intensity was corrected for the scattering volume and the scattering solvent at each scattering angle, and finally plotted as a function of the magnitude of the scattering vector q = 4πn sinθ / λ (where n is the refractive index of the solvent). Toluene was used to match the observed photons to the excess Rayleigh ratio. The Rayleigh ratios of the sol sample and the gel sample were adjusted to be equal at a magnification of 1.2 × 10 4 and matched to the scattering intensity of small-angle X-ray scattering (differential scattering cross-section) in the low q region. All experiments were carried out at 25°C.

[0164] 5. Small-Angle X-ray Scattering SAXS measurements were performed using a small-angle instrument (SAXSpoint 2.0, Anton-Paar) of the lab source. The sample contained in a sealed flat cell equipped with two 30-μm-thick glass windows was placed in a vacuum chamber and irradiated with microfocus x-rays from a Cu-Kα source with a wavelength of 1.542 Å. The beam diameter applied to the sample was set to approximately 1 mm. The distance from the sample to the detector was 812 mm. The scattered x-rays were collected with a two-dimensional hybrid pixel detector (2D Eiger R 1M, Dectris). The exposure time for each sample was set to 24 hours. The scattering intensity was circularly smoothed to obtain a one-dimensional (1D) intensity profile, and then corrected for the incident beam flux, sample absorption and thickness, exposure time, and scattering of the cell and solvent using a custom-made data processing package Red2D (https: / / github.com / hurxl / Red2D) with scientific data analysis software (Igor Pro 8, WaveMetrics). The intensity was plotted as a function of the magnitude of the scattering vector q. Absolute intensity (differential scattering cross-section) and the precise distance from the sample to the detector were corrected using glassy carbon (National Institute of Standards and Technology, USA) and silver behenate standard (Nagara Science, Japan), respectively. All measurements were carried out at 25°C.

[0165] 6. Two-dimensional static light scattering by microscopy A glass tube filled with a pregel solution was placed on the stage of an inverted microscope (ECLIPSE Ti-U, Nikon). A coherent laser beam with a wavelength of 488 nm and a diameter of 0.5 mm was directed onto the glass tube. The scattered light was collected through a 10x objective lens (TU Plan Fluor EPI, Nikon) and recorded with an EMCCD camera (iXon3, Andor Technology). The measurements were performed at room temperature (about 25°C).

[0166] 7. Time-resolved DLS During the gelation process, time-resolved DLS was measured using the same light scattering instrument (ALV-5000, ALV) as described in the section of "4.1D Static Light Scattering". The scattering angle was fixed at 90°. Time-resolved measurements were performed during the gelation process with data collection of 30 seconds per frame. All measurements were carried out at 25 °C.

[0167] 8. DLS at Multiple Sample Positions The same light scattering device as described above was used. All samples were measured at 100 different positions around one position for 300 seconds using an automatic rotation and vertical movement device. All measurements were carried out at 25 °C.

[0168] Results First, as a space-filling unit, a star polymer composed of poly(ethylene glycol) with four arms as a branched polymer was used (Figure 5(A)). Next, to ensure that the star polymers uniformly and densely filled the space as assumed by the bond percolation model, the star polymers were dissolved in a good solvent at a concentration (12 wt%) well above the concentration (~6 wt%) at which the branched chains of adjacent star polymers overlap (Figure 5(B)). To prevent the chains of the star polymers from separating during crosslinking, acetonitrile anhydride was selected as a solvent that exhibits excellent affinity for the star polymers used in this study (Figure 5(C)). Furthermore, to remove as much dust and nanobubbles as possible from the solution, the solution was filtered through an ultra-fine syringe filter with an average pore size of 20 nm. After adding a stoichiometric amount of crosslinking agent to the solution, here a small molecule difunctional crosslinking agent was used as the crosslinking agent, the star polymer solution underwent a sol-gel transition (Figure 5(C,D)). Since the star polymer solution did not exhibit abnormal scattering of light due to gel structure inhomogeneity, a very transparent gel was obtained (Figure 5(D)). A more accurate gelation point could be measured as the intersection of the storage modulus G' and the loss modulus G" by dynamic viscoelasticity measurement (Figure 5E).

[0169] When the G' (= 10400 Pa) of the star polymer gel is substituted into the above equations (S2) and (S3), the connectivity of the star polymer is calculated to be 0.92. Considering that the conversion rate of the end groups of the star polymer is about 0.95 according to the manufacturer's report, it was found that the connectivity of this gel is almost equal to an ideal virtual network.

[0170] Next, in order to examine the nanometer structure in the gel, SLS and SAXS were used to evaluate the spatial function of the branched polymer chains in the Fourier space. Figure 6 shows the scattering profiles of the pregel solution (Sol) and the fully developed gel (Gel) synthesized by the bond percolation scheme. The SLS intensities of the sol sample and the gel sample were scaled by the same coefficient so as to match the intensity I(q) of SAXS in the low-q-limit region of the scattering vector q. Surprisingly, the scattering profiles of the polymer gel and the non-crosslinked pregel solution were almost identical. That is, the spatial correlation between the polymer chains did not change due to crosslinking. This strongly suggests that the gelation of the star polymer proceeded by bond percolation. Hereinafter, the gel of this example is referred to as a "bond percolation gel".

[0171] Another point to note is that the unusually strong scattering in the low-q region that was always observed in past polymer gels was not observed in the bond percolation gel.

[0172] To further confirm the uniformity of the bond percolation gel, the inventors conducted a laser speckle test to visualize the spatial defects in the gel. As shown in Figure 7, a sample for preparing a gel placed in a glass tube was irradiated with coherent light, and the two-dimensional pattern of the scattered light was monitored with an electron multiplying charge coupled device (EMCCD) camera. As shown in Figures 8(A) and (B), the scattering patterns were the same from the pregel solution to the fully developed gel in the bond percolation gel. Unexpectedly, there was almost no change in the scattering pattern even at the gelation point. Static laser speckles (i.e., bright spots), which are indicators of spatial defects, were not observed at all (data omitted for the video).

[0173] To make this finding clearer, the same measurements were also carried out on a conventional gel synthesized by copolymerizing a small molecule monomer and a crosslinking agent in water using the common monomer N-isopropylacrylamide (NIPAM) (M. Shibayama et al., Macromolecules 29, 8746-8750 (1996)). This monomer / crosslinking agent system acts as a typical site-bond percolation because the small molecule monomer and the crosslinking agent do not fill the space of the solution. As expected, the scattering pattern of the conventional gel changed significantly during the formation of the network structure (Figs. 8 (C), (D)). As the reaction progressed, the total scattering intensity increased and reached a maximum at the sol-gel transition point. Furthermore, when the initial gel network was formed, a large number of laser speckles reflecting the inhomogeneous distribution of polymer chains were observed (data omitted for the video).

[0174] The above results of static scattering indicate that the spatial uniformity in the polymer gel was significantly improved by the proposed bond percolation scheme.

[0175] Next, the inventors evaluated the uniformity of the gel network structure from the perspective of time correlation. First, the time correlation function (g2) of the scattering intensity at a fixed sample position was measured by time-resolved dynamic light scattering (DLS) throughout the gelation process. Although the sol-gel transition definitely occurred approximately 60 minutes after the start of the reaction, there was no perceptible change in the time correlation function for the bond percolation gel (Fig. 9 (A)). The g2 curve decreased as a single master curve regardless of the degree of crosslinking. The behavior of g2 for the bond percolation gel is completely different from that of any other gel - where g2 changes significantly at the sol-gel transition point and a perceptible suppression of the initial value g2(0) is commonly observed after gel formation - (see, for example, T. Ngai, J. Phys. Chem. B108 5532-5540 (2004); T. Sakai, Macromolecules 41, 5379-5384 (2008)).

[0176] Figure 9(B) is an example of the gelation of a conventional gel using a NIPAM monomer / crosslinker system. The suppression of g2(0) indicates the existence of local vibrations that do not exceed the observation length scale of ~q within the experimental time, and the origin of such local vibrations in the gel is uncertain, but is often due to the restricted dynamics of the crosslinker and its adjacent polymer chains. However, such suppression of g2(0) was not observed in the bond percolation gel (Figure 9(A)). This indicates that local vibrations are not an inherent property of the polymer gel. Since the bond percolation gel showed no signs of any spatial defects, it is very likely that the local vibrations observed in past gels are due to locally generated spatial defects, which can be removed using the percolation scheme of this example. -1 Polymer gels are non-ergodic materials, and since the measurement at one sample position shown in Figure 9(A) may not represent the dynamics of the entire network structure of the gel, the inventors then performed additional DLS measurements at 100 randomly selected different sample positions of a fully developed gel to examine whether the local time correlation function and the ensemble-averaged time correlation function match. As a result, as shown in Figure 9(C), the g2 curves of the bond percolation gel at a plurality of different sample positions were in agreement with each other. The ensemble-averaged function g

[0177] also agreed with the individual local g2 curves. In contrast, as shown in Figure 9(D), the behavior of the conventional gel is significantly different from the position-dependent relaxation of the bond percolation gel, and each g2 curve in the conventional gel depends on the sample position and does not match the ensemble average. The agreement between the local dynamics and the ensemble-averaged dynamics suggests that the concentration change in the bond percolation of this example is ergodic. 2E

[0178] The gel with a uniform network of the present invention is not only expected to be applied as a high-performance separation membrane, but also can achieve the theoretical upper limit of transparency that can be achieved as a soft material because abnormal light scattering due to structural non-uniformity does not occur.

[0179] Test Example 2 Materials and Methods 1. Preparation of Star Polymer Gel All of the Bond percolation gel, Site percolation gel, and non-ideal percolation gel were synthesized by cross-linking tetra-PEG-NHS (molecular weight 20,000 g mol -1 ) which is a branched polymer, with amino-PEG4-amine at approximately equimolar ratio (Figure 10A, B). The overlap concentration of tetra-PEG-NHS used here is about 6 wt%. In the synthesis of the Bond percolation gel, the concentration of tetra-PEG-NHS was set to 12 wt% which is about twice higher than the overlap concentration, and anhydrous acetonitrile which is a good solvent was used as the solvent (Figure 10C,F). On the other hand, in the synthesis of the Site percolation gel, the solvent remained anhydrous acetonitrile which is a good solvent, but the concentration of tetra-PEG-NHS was set to 3 wt% which is about half of the overlap concentration (Figure 10D,G). In the Site percolation gel, the branched polymer does not fill the space densely enough, and it is possible to form a network structure with various spatial arrangements. In the synthesis of the Non-ideal bond percolation gel, the concentration of tetra-PEG-NHS was set to 12 wt% which is sufficiently high, but the solvent was changed to water with poor solubility (Figure 10E,H). Because of the low solubility of the solvent, the branched polymer easily forms aggregates before cross-linking, and the branched polymer cannot fill the space uniformly. In any of the gelation reactions, acetic acid or phosphate was added to the solvent so that the gelation time was about 5 - 10 minutes to control the cross-linking reaction rate. Some evaluations of the obtained gels were carried out in the same manner as in Test Example 1.

[0180] Results 1. Dynamic Viscoelasticity Measurement Under any synthesis conditions, the storage modulus G' exceeded the loss modulus G" within 10 minutes, and gelation was confirmed (Figs. 10A, B, C). 2. Two-dimensional static light scattering by microscope By using 2D laser speckle measurement, more bright and dark spots (speckles) were observed for site percolation gels and non-ideal percolation gels compared to bond percolation gels (Figs. 11D, E, F). The normalized line profiles of the scattering intensity along the dotted lines in Figs. 11D, E, F are shown in Figs. 11G, H, I, respectively. is the average scattering intensity in the line profile, and ΔI is at each point is the difference from. ΔI / Qualitatively shows that the smaller the absolute value of [[ID=]], the more uniform the structure is formed. Deviating from the preparation conditions of the Bond percolation gel indicates that a non-uniform gel is formed. 3. Small-angle X-ray scattering Each gel was measured by SAXS (Figure 12A) and compared with the theoretical line predicted for the polymer solution corresponding to the composition before crosslinking of the gel, which contains the same components as each gel at the same concentration (Figure 12B). The theoretical lines are shown as solid lines in the figure. All the theoretical lines shown here correspond to cases above the overlap concentration. ξ is the correlation length that depends only on the concentration defined above the overlap concentration and does not depend on the uniformity or non-uniformity of the structure. Therefore, the discussion is made after normalizing with ξ in the SAXS profile. The Bond percolation gel almost coincides with the theoretical line, while deviations from the theoretical line of the corresponding polymer solution were observed in the Site percolation gel and the Non-ideal bond percolation gel (Figure 12B). The deviation from the theoretical line of the polymer solution indicates that structural defects that did not exist in the uncrosslinked solution are formed. Therefore, it was shown from the SAXS profile that the Bond percolation gel is extremely uniform, and the Site percolation gel and the Non-ideal bond percolation gel contain structural defects.

[0181] Test Example 3 Tetra-PEG-SH, molecular weight 20,000 gmol -1 was dissolved in acetonitrile in a glass test tube so that the concentration became 12 wt%, and a small amount of 30 wt% hydrogen peroxide solution was added. Since SH groups react with each other by the oxidation reaction with hydrogen peroxide to form disulfide bonds (S-S), gels were formed by the A-A type crosslinking reaction (without using a crosslinking agent) between tetra-PEG-SH. The formation of the gel was confirmed by inverting the glass test tube so that the reaction solution of tetra-PEG-SH did not fall by gravity. Dynamic light scattering measurements were performed at 100 different locations on the prepared gel, and the time correlation function g2 of the scattering intensity was measured. The g2 at 100 locations was at a delay time of 0.001 ms

Claims

1. A gel comprising a polymer prepared by crosslinking a plurality of branched monomers or branched polymers, and a good solvent for the plurality of branched monomers or branched polymers, wherein the polymer in the gel is crosslinked at a concentration equal to or higher than the concentration at which the chains of adjacent branched monomers or branched polymers among the plurality of branched monomers or branched polymers overlap each other. From the time correlation function of the gel in the range of a delay time of 0.001 to 0.1 (ms) at the gelation point, whether the rate of change from the time correlation function at a time 10 times the time required for gelation to the time correlation function after that is within ±10%, and / or When compared with a polymer solution corresponding to the composition before crosslinking of a gel in which the types and concentrations in the gel of the polymer prepared by crosslinking the plurality of branched monomers or branched polymers are the same, and the types and concentrations in the gel of the good solvent are the same, the maximum rate of change of the scattering intensity I(q) at 0.005 Å -1 in the profile of static laser light scattering (SLS) between the uncrosslinked polymer solution and the gel is in the range of -50% to +100%. Gel.

2. When compared with a polymer solution corresponding to the composition before crosslinking of a gel in which the types and concentrations in the gel of the polymer prepared by crosslinking the plurality of branched monomers or branched polymers are the same, and the types and concentrations in the gel of the good solvent are the same, the maximum rate of change of the scattering intensity I(q) at 0.1 Å -1 in the profile of the small-angle X-ray scattering spectrum (SAXS) between the uncrosslinked polymer solution and the gel according to Claim 1 is in the range of -50% to +100%.

3. The plurality of branched monomers or branched polymers are crosslinked via a crosslinking agent, and the combination of the functional group of the branched monomer or branched polymer and the crosslinking agent is at least one selected from the group consisting of azide-alkyne, maleimide-thiol, biotin-avidin, biotin-streptavidin, silane-silica particles, bromo-thiol, iodo-thiol, OPSS-thiol, benzophenone-nucleophilic reagent, ATFBA-nucleophilic reagent, alkyne-azide, hydrazine-amine, aldehyde-amine, acryloyl-olefin, epoxy-amine, epoxy-alcohol, epoxy-thiol, acid-amine, acid-alcohol, acid-thiol, and hydroxyl group-acid, or or the plurality of branched monomers or branched polymers include a first branched monomer or branched polymer having a nucleophilic functional group and a second branched monomer or branched polymer having an electrophilic functional group reactive with the nucleophilic functional group, the nucleophilic functional group is a thiol group or -COOPhNO 2 (Ph is an o-, m-, or p-phenylene group), and the electrophilic functional group is a maleimidyl group, N-hydroxy-succinimidyl (NHS) group, sulfosuccinimidyl group, phthalimidyl group, imidazolyl group, acryloyl group or nitrophenyl group, or the nucleophilic functional group is a thiol group, amino group, or -COOPhNO 2 (Ph is an o-, m-, or p-phenylene group, and the electrophilic functional group is a maleimidyl group, sulfosuccinimidyl group, phthalimidyl group, imidazolyl group, acryloyl group or nitrophenyl group, or the plurality of branched monomers or branched polymers are crosslinked by the formation of a disulfide bond. The gel according to claim 1 or 2.

4. The gel according to any one of claims 1 to 3, containing the polymer in the range of 6% to 99% by weight.

5. The gel according to any one of claims 1 to 4, having a light transmittance of 95% or more.

6. A method for producing the gel according to any one of claims 1 to 5, comprising: mixing a plurality of branched monomers or branched polymers in a good solvent at a concentration equal to or higher than the concentration at which the chains of adjacent branched monomers or branched polymers among the plurality of branched monomers or branched polymers overlap; and polymerizing the plurality of branched monomers or branched polymers to obtain a gel. A method comprising the above.

7. The production method according to claim 6, further comprising adding a crosslinking agent before polymerizing the plurality of branched monomers or branched polymers.

8. Polymerizing the plurality of branched monomers or branched polymers includes crosslinking the plurality of branched monomers or branched polymers by one or more stimuli selected from the group consisting of heat, temperature, pH, gas, magnetism, vibration, humidity, water, electromagnetic waves, light, electricity, and pressure. The production method according to claim 6 or 7.

9. The production method according to any one of claims 6 to 8, further comprising a step of purifying a mixed solution containing the plurality of branched monomers or branched polymers and the good solvent before polymerizing the plurality of branched monomers or branched polymers.

10. A gel sheet containing the gel according to any one of claims 1 to 5.

11. A porous polymer crosslinked body obtained by reducing or removing the good solvent from the gel according to any one of claims 1 to 5.

12. Cosmetics, pharmaceuticals, quasi-drugs, medical products, additives, paints, ink bases, absorbents, sustained-release agents, carriers, glass substitutes, adhesives, adhesives, heat insulators, sound absorbers, shock absorbers, load distributors, electrode materials, optical fibers, films, fillers, fillers, filters, separation membranes or electrode materials containing the gel according to any one of claims 1 to 5, the gel sheet according to claim 10, or the porous polymer crosslinked body according to claim 11.

13. Use of the gel according to any one of claims 1 to 5, the gel sheet according to claim 10, or the porous polymer crosslinked body according to claim 11 for the production of cosmetics, pharmaceuticals, quasi-drugs, medical products, additives, paints, ink bases, absorbents, sustained-release agents, carriers, glass substitutes, adhesives, pressure-sensitive adhesives, heat insulators, sound absorbers, shock absorbers, load dispersants, electrode materials, optical fibers, films, fillers, fillers, filters, separation membranes or electrode materials.

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