KR101968500B1 - Method for Predicting Swelling Behaviour of Thermo-responsive Hydrogels - Google Patents

Abstract

In this disclosure, molecular thermodynamic-based model and group contribution are applied to hydrogel polymers having a crosslinked elastic network structure to determine the physical properties of the hydrogel under various conditions (e.g., temperature and crosslinking agent fraction) Or volume expansion) behavior is provided.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for predicting the swelling behavior of a thermo-responsive hydrogel,

The present disclosure relates to a method for predicting the swelling behavior of a thermally responsive hydrogel. More specifically, the present disclosure relates to a hydrogel polymer having a crosslinked elastic network structure by applying a molecular thermodynamic-based model and group contribution to the hydrogel polymer under various conditions (e.g., temperature and crosslinking agent fraction) (Swelling or volumetric expansion) behavior of the polymer.

A hydrogel generally refers to a material having a network structure of a three-dimensional hydrophilic polymer capable of absorbing (containing) a large amount of water while maintaining its semi-solid morphological characteristics, and thus is referred to as an aqueous swelling polymer. That is, the hydrogel may mean a water-insoluble, covalently crosslinked hydrophilic polymer. Such hydrogels have been known for the first time in about 1960 and have been applied in various fields such as sanitary articles such as diapers, contact lenses, cosmetics, foods, drug storage, and the like.

It is known that a hydrogel has at least 15 times its molecular weight and has the property of swelling by absorbing water and a biological fluid. A hydrogel formed by chemical or physical crosslinking usually forms a three-dimensional hydrophilic polymer network. A hydrogel formed by using a hydrophilic polymer is a hydrophobic polymer (hydrophobic group collapses in the presence of water so that it is less exposed to water molecules ) Compared with the control.

The swelling behavior of hydrogels has a tendency to change in response to various types of physicochemical stimuli (e.g., pH, ionic strength, solvent composition, gel structure, temperature, etc.). In the field of bioscience, pharmaceuticals, pharmaceuticals, materials, fusion electric and electronic fields, specifically sensors, actuators, drug delivery systems, catalysts, agricultural processing products, etc., by using changes in the stimulus-responsive equilibrium behavior of hydrogels It has attracted much attention because it has potential to be utilized.

The swelling behavior of the hydrogel is known to be closely related to the phase equilibrium of the linear polymer gel, and the swelling behavior of the gel network can theoretically be described on the basis of a direct extension of the phase equilibrium theory in the linear chain polymer solution. Prediction methods for the swelling behavior of hydrogels have been conventionally proposed using factors of elastic contribution from the crosslinked gel network structure and mixed contribution factors from the interaction of the polymer and solvent, and recently, as the quasi-chemical thermodynamic model Attempts have been made to analyze the gel swelling phenomenon by combining the theoretical mixing model with the Flory-Rehner elastic model, or by using the lattice fluid model or the PC-SAFT (perturbed-chain statistical association fluid theory). In this regard, the present inventors have also developed a method for evaluating the swelling behavior of various hydrogels from the equilibrium state of the polymer solution, and further investigated the influence of the salt on the swelling behavior (Bae et al., Polymer Bae et al., Polymer 2013, 54, 2138-2145).

If the swelling behavior of the hydrogel can be predicted without any special experiment, time and cost according to the experiment can be saved, and the convenience of designing the hydrogel having desired physical properties can be provided. For this reason, a method for accurately predicting the physical properties of the hydrogel is continuously required. Conventional methods can increase accuracy to some extent for certain hydrogel systems, but there are limitations in applying them to various hydrogel systems because they use adjustable parameters. To overcome these drawbacks, a group contribution method has been proposed as a method for predicting thermodynamic properties such as vapor pressure, heat capacity, critical properties, and equilibrium properties.

For example, U.S. Patent No. 6,687,621 and Japanese Patent Laid-Open No. 2003-105090 disclose a method of determining the desired physical properties for an individual polymer in an existing polymer set, (ii) determining at least a part of the molecular structure of the individual polymer (Iii) specifying a mathematical function that associates the selected group of descriptors with the desired properties, or (iii) specifying a mathematical function that associates the selected group of descriptors with the desired properties, or a composition comprising a monomer in a polymeric material comprising a multiblock copolymer A method of predicting the morphology and the role physical properties of the polymer material by using a simulation model such as the Monte Carlo method is disclosed. In order to implement these methods, a group contribution method is applied.

However, the conventional method using the group contribution method has mainly been applied to the polymer solution system, and there has been a limitation in applying the crosslinked polymer gel system as a target in the present disclosure.

In this regard, as a method for predicting the swelling behavior of the hydrogel, a modified double-lattice (MDL) model, which overcomes the disadvantages of the known double-lattice (DL) model, A method for predicting the swelling behavior of the hydrogel can be considered, but there still exists a problem that the swelling behavior of the hydrogel is not exactly matched with the experimentally measured swelling behavior.

Accordingly, there is a continuing need for a prediction method based on a new model equation so as to more accurately predict the behavior of the hydrogel than the conventionally proposed method.

Accordingly, in an embodiment according to the present disclosure, a novel molecular thermodynamic-based model and group contribution are applied, wherein at least one functional group or moiety in the polymer constituting the hydrogel is separated and identified And by using library parameterized group parameters for each of them and by reflecting the fraction of the cross-linker in hydrogel synthesis, the bulk properties of the hydrogel under various conditions (hydrogel temperature, fraction of cross-linking agent, etc.) And to provide a method for designing hydrogels of desired physical properties without performing unnecessary experiments.

According to one aspect of the present disclosure,

As a method for predicting the swelling behavior of a hydrogel,

a) separating and identifying the repeating units constituting the hydrogel polymer by functional groups;

)를 결정하는 단계, b) calculating an average number of elastically active chains between cross-linking points according to the van der Waals volume measured experimentally for each of the specified functional groups according to the following equation (9) linking sites;

),

&Quot; (9) "

는 하이드로겔 내부의 가교제(cross-linker)의 몰 분율이고,

및

는 각각 하이드로겔 고분자의 반복 단위 및 용매의 반 데르 발스 체적임;In this formula,

Is the mole fraction of the cross-linker in the hydrogel,

And

Is the van der Waals volume of the repeating unit and solvent of the hydrogel polymer, respectively;

를 하기 수학식 7에 의하여 결정하는 단계,c) Applying the group contribution method based on ε ^* , δε ^* , δε ^H and δε ^S experimentally obtained for each of the above specified functional groups,

(7), < / RTI >

&Quot; (7) "

Where [epsilon] ^* and [delta] [epsilon] ^* are energy parameters for general interaction and specific interaction, respectively, superscripts " H " and " S " indicating enthalpy contribution and entropy contribution, respectively; And

및

를, 하이드로겔 네트워크 내부에서의 용매의 화학적 포텐셜에 대한 하기 수학식 10에 대입하여 고정된 온도(T)에서 팽윤 상태에 있는 하이드로겔의 체적 분율(φ _g )을 구함으로써 팽윤도(swelling ratio; 1/φ _g )를 산출하는 단계,The determined

And

(Swelling ratio: 1) by calculating the volume fraction ( ? _G ) of the hydrogel in a swollen state at a fixed temperature (T) by substituting the chemical potential of the solvent in the hydrogel network into the following equation / [ phi] _g )

&Quot; (10) "

는 보편적 파라미터(universal parameter)이고,

으로 설정됨;In this formula,

Is a universal parameter,

Lt; / RTI >

Is provided.

According to one embodiment, each of the ε ^* , δε ^* , δε ^H, and δε ^{S is} represented by the following equations (11) and (13) when the hydrogel polymer is a homopolymer, 11 and 14, respectively.

&Quot; (11) "

는 분자 i 내 관능기(k)의 수이고, 그리고

는 관능기(k)의 체적임,Wherein V _i is the volume of the molecule i ,

Is the number of functional groups ( k ) in the molecule i , and

Is the volume of the functional group ( k )

&Quot; (13) "

Wherein R, θ _k being the volume fraction of the hydrogel homopolymer within the functional group (k),

&Quot; (14) "

는 단량체 i 내 관능기(k)의 체적 분율임.Where x _i is the mole fraction of monomer i in the hydrogel copolymer,

Is the volume fraction of the functional group ( k ) in the monomer i .

According to an exemplary embodiment, the hydrogel may be a non-ionic hydrogel.

는 11.44 ㎤/mol로 설정될 수 있다.According to an exemplary embodiment, the solvent is water,

Can be set to 11.44 cm < 3 > / mol.

는 0.3으로 설정될 수 있다. According to an exemplary embodiment, the universal parameter

Can be set to 0.3.

According to another aspect of the present disclosure,

As a method for predicting the swelling behavior of a salt-containing hydrogel,

a) separating and identifying the repeating units constituting the salt-containing hydrogel polymer by functional groups;

)를 결정하는 단계, b) calculating an average number of elastically active chains between cross-linking points according to the van der Waals volume measured experimentally for each of the specified functional groups according to the following equation (9) linking sites;

),

&Quot; (9) "

는 하이드로겔 내부의 가교제(cross-linker)의 몰 분율이고,

및

는 각각 하이드로겔 고분자의 반복 단위 및 용매의 반 데르 발스 체적임;In this formula,

Is the mole fraction of the cross-linker in the hydrogel,

And

Is the van der Waals volume of the repeating unit and solvent of the hydrogel polymer, respectively;

를 하기 수학식 15에 의하여 결정하는 단계,c) Applying the group contribution method based on ε ^* , δε ^* , δε ^H and δε ^S experimentally obtained for each of the above specified functional groups,

(15), < / RTI >

&Quot; (15) "

Where ε ^* and δε ^* are energy parameters for general interactions and specific interactions, respectively, δε ^salt / k is a salt-specific interaction parameter, C is the salt concentration in mol / L , And superscripts " H " and " S " respectively indicate enthalpy contribution and entropy contribution; And

및

를, 하이드로겔 네트워크 내부에서의 용매의 화학적 포텐셜에 대한 하기 수학식 10에 대입하여 고정된 온도(T)에서 팽윤 상태에 있는 하이드로겔의 체적 분율(φ _g )을 구함으로써 팽윤도(swelling ratio; 1/φ _g )를 산출하는 단계,The determined

And

(Swelling ratio: 1) by calculating the volume fraction ( ? _G ) of the hydrogel in a swollen state at a fixed temperature (T) by substituting the chemical potential of the solvent in the hydrogel network into the following equation / [ phi] _g )

&Quot; (10) "

는 보편적 파라미터(universal parameter)이고,

으로 설정됨;In this formula,

Is a universal parameter,

Lt; / RTI >

Is provided.

The method of predicting the swelling behavior of the hydrogel provided according to embodiments of the present disclosure is based on the molecular thermodynamics based model and group contribution method, and thus the properties of hydrogels with significantly improved accuracy compared to the conventionally known predictive models Or volumetric expansion) behaviors. Particularly, by grouping the group parameters for each of a plurality of functional groups or moieties constituting the polymer hydrogel and reflecting the fraction of the cross-linker in hydrogel synthesis, various conditions (temperature of the hydrogel, Fraction of cross-linking agent, etc.), as well as designing hydrogels of desired physical properties, it is possible to omit unnecessary experiments. Therefore, the present invention can be effectively applied to the development of packages for predicting the physical properties with respect to the swelling degree or the degree of degradation of ultra-high water absorbent resin (SAP), biodegradable resin and the like.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a flow chart schematically illustrating the process of calculating the degree of swelling of a hydrogel through a group contribution method in one embodiment of the present disclosure;
FIG. 2 is a view exemplarily showing a series of procedures for determining the swelling behavior of a hydrogel when PNIPA (poly-N-isopropyl acrylamide; crosslinker molar fraction: 0.0388) is used as the hydrogel polymer;
3A and 3B are graphs showing the swelling curves of the hydrogel system in the PNIPA / water system and the PNCPA / water system, respectively (solid line: the result calculated according to the example, the dotted line: the result calculated according to the conventional MDL model, And the sign is experimental data);
Figure 4 is a swelling curve of various N-substituted polyacrylamide hydrogel systems (the sign is experimental data, the solid line is the result calculated using the predictive model according to the embodiment);
Figures 5A-5C are graphs showing the swelling curves of the hydrogel system in the PNIPMA / water system, the PMEO2MA / water system and the PVCL / water system (reference numerals are experimental data and solid lines indicate, Lt; / RTI >
6A-6C are swelling curves of a copolymer hydrogel system with hydrophobic comonomers, wherein P (NIPA-co-NTBA) / water system, P (NIPA-co-ENAG) co-HEMA) / water system (the sign is the experimental data and the solid line is the result calculated using the prediction model according to the embodiment);
Figure 7 is a swelling curve of a copolymer hydrogel system with hydrophilic comonomer (NDMA) (the sign is experimental data and the solid line is the result calculated using the predictive model according to the embodiment); And
8A-8C are swelling curves of a salt-containing PNIPA hydrogel system, respectively, which refer to the PNIPA / water / NaCl system, the PNIPA / water / NaBr system and the PNIPA / water / NaI system Is the result calculated using the prediction model according to the embodiment, and the salt concentration is M (mol / L)).

The present disclosure can be all attained by the following description. The following description should be understood to describe preferred embodiments of the present invention, but the present invention is not necessarily limited thereto. It is to be understood that the accompanying drawings are included to provide a further understanding of the invention and are not to be construed as limiting the present invention. The details of the individual components may be properly understood by reference to the following detailed description of the related description.

In addition, the following referenced documents are incorporated herein by reference and can be understood to constitute at least a part of the disclosure.

The terms used in this specification can be defined as follows.

&Quot; Polymer " includes both homopolymers and copolymers, and the copolymer can be understood to include random copolymers and block copolymers.

A "hydrogel" can generally refer to a three-dimensional, hydrophilic or amphipathic polymer network capable of absorbing a large amount of water as a crosslinked polymer of a hydrophilic monomer, said polymer network comprising a homopolymer or copolymer And exhibit insolubility due to the presence of covalent chemical or physical (ionic, hydrophobic interactions, entanglement, etc.) crosslinking linkages. At this time, the crosslinked link provides network structure and physical integrity, and hydrogels can exhibit thermodynamic compatibility with a medium such as water swelling in an aqueous medium. Hydrogels can swell and contract within an aqueous solution.

By " gel " is usually a gel having two continuous phases, the hydrogel being the liquid phase. Pores may be present in the chains of the network in the hydrogel and a significant proportion of the pores may be connected in such a way as to have dimensions of, for example, about 1 to 1000 nm, specifically about 10 to 500 nm, more specifically 30 to 100 nm .

A " swelling ratio " may mean a volume ratio when the sample of a particular composition (e.g., a hydrogel) is substantially fully hydrated for its volume when it is substantially dehydrated. The degree of swelling of the hydrogel may be determined by the hydrophilicity, degree of crosslinking, porosity of the particles, etc. of the polymer constituting the hydrogel.

A " crosslinked polymer network " can refer to hydrophobic molecules, hydrophilic molecules, and interconnected structures in which crosslinking is formed between hydrophobic and hydrophilic molecules.

When an element is referred to as " comprising ", it means that it may further include other elements unless otherwise stated.

On the other hand, the prior art described in detail below is included as a reference in this specification.

According to embodiments of the present disclosure, in order to overcome the limitations of the conventional model in accurately predicting the behavior of a hydrogel, a group contribution method that considers the contribution to the structure that constitutes the molecule, .

The " group contribution method " is based on the theoretical assumption that the physical properties of any material can be described as the sum of contributions from individual functional groups. That is, the contribution of a specific functional group to a physical property of a molecule can be quantitatively defined.

In this regard, an accurate calculation of the group contribution is highly dependent on the thermodynamic model used. In view of the above, an association theory (Sanchez, AC Sanchez, AC Balazs, Macromolecules, 1989) is proposed in order to consider the interaction energy between the complex type polymer / solvent based on the improved double- 22, 2325-2331) to provide a new model capable of predicting the swelling behavior of a hydrogel with high accuracy.

In this regard, the group parameters are calculated by using an improved dual-lattice model to calculate intermolecular interaction energy contributions, and based on a thermodynamic model that takes into account the elasticity of the polymer network using the improved Flory-Rehner model, Hydrogel < / RTI > and copolymer hydrogel systems.

Also, according to another embodiment of the present disclosure, in order to take into account the effect of salt, which is a key variable in the utilization of the superabsorbent resin, it is possible, by introducing salt-specific interaction parameters, It is possible to obtain a good agreement result with respect to the swelling test result of the system.

Hydrogel

In general, hydrogels are classified into two groups according to their cross-linked forms of polymers (for example, hydrophilic polymers): (i) a chemical hydrogel, which is a hydrogel covalently linked with polymers, When exposed to the environment, swelling by moisture continues to occur until equilibrium is reached; And (ii) the hydrophilic polymer as a physical hydrogel is crosslinked by a physical bond (specifically, an electrostatic interaction, a hydrogen bond, a hydrophobic interaction, etc.) which is not a chemical bond.

Due to the crosslinking structure described above, hydrogels exhibit inferiority and tend to dissolve without crosslinking in such polymers. In particular, the three-dimensional network structure is caused by crosslinking, which can increase the mechanical stability of the hydrogel by increasing the crosslinking ratio. However, the mechanical stability tends to decrease when the hydrogel is in a swollen state.

According to one embodiment, the polymer constituting the hydrogel may be a natural polymer-based material such as hyaluronic acid, alginic acid, pectin, carrageenan, chondroitin (sulfate), dextran Cellulose, chitosan, polylysine, collagen, gelatin, carboxymethyl chitin, fibrin, agarose, pullulan, cellulose, etc. may be used alone or in combination.

According to one example of a method for producing an exemplary synthetic polymeric hydrogel, which is more typically a synthetic polymeric hydrogel, a hydrogel is typically prepared by adding a monomer of a hydrophilic (or water-soluble) (For example, precipitation polymerization). In an exemplary embodiment, the polymer constituting the hydrogel may be in the form of a homopolymer and / or a copolymer. In this regard, in the case of copolymerization, the comonomer may be hydrophilic or hydrophobic.

According to an exemplary embodiment, the hydrogel polymer can be prepared by polymerizing a monomer having an ethylenically unsaturated group. The ethylenically unsaturated monomer is not particularly limited, but may be a monomer having an unsaturated double bond at the terminal, for example, an acrylic It may be a monomer.

Exemplary monomers include, but are not limited to, acrylic acid, methacrylic acid, acrylamide, methacrylamide, alkyl- (meth) acrylamide, (Meth) acrylamide, N, N-di-C 1 -C 4 alkyl- (meth) acrylamide ) And the like.

More specific monomer compounds include N-butyl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate (Meth) acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, 2- (2-methoxyethoxy) ethyl methacrylate (2-methoxyethoxy) ethyl methacrylate, N- (2-hydroxyethyl) acrylamide, N-methyl acrylamide, Amide (N-isopropylacrylamide), N-tert- N-dimethylacrylamide (NDMA), N, N-diethylacrylamide (NDMA), N-butoxymethyl acrylamide, N-methoxymethyl Acrylamide, N-methoxymethyl acrylamide, N-methoxyisopropyl acrylamide, N-cyclopropylacrylamide, ethyl-N-acryloylglycin Vinylcaprolactam, N-methoxymethyl methacrylamide, 2-acrylamidoglycolic acid or 2-carboxyethyl acrylate, and the like. 2-hydroxy-5-methoxyacetophenone, 2-hydroxyethyl disulfide and the like can be used alone or in combination, But the present invention is not limited thereto.

In addition, examples of the crosslinking agent include N, N "-methylenebisacrylamide, ethylene glycol, glycerin, polyoxyethylene glycol, calcium chloride, bisacrylamide, diarylphthalate, diaryl adipate, Ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, triglycerine diglycidyl ether, triarylamine, glyoxal, etc., and they may be used alone or in combination. The types of the polymers and crosslinking agents constituting the hydrogels listed above are provided for illustrative purposes, and the present disclosure is not limited thereto.

)를 결정하는 과정에서 전체 하이드로겔의 가교제 함량이 고려된다. 즉, 가교제의 종류에 상관없이 가교제의 량에 따른 하이드로겔의 팽윤 현상을 모사하는 것으로 이해될 수 있다. However, in the case of the model provided according to the concrete example of the present disclosure, the type of crosslinking agent is not considered as a group contribution method, and the average number of elastic activity facts between crosslinking points

), The crosslinking agent content of the entire hydrogel is considered. That is, it can be understood that the swelling phenomenon of the hydrogel according to the amount of the crosslinking agent is simulated regardless of the type of the crosslinking agent.

According to an exemplary embodiment, the content (molar fraction) of the cross-linking agent relative to the entire monomers of the polymer constituting the hydrogel is, for example, about 0.1 to 10 mol%, specifically about 0.5 to 5 mol% May range from 1 to 3 mol%, but the present disclosure is not limited thereto as long as it can be changed in consideration of the kind of polymer used and the like.

In addition, exemplary reaction temperatures may range from about 0 to 100 캜, specifically about 5 to 80 캜, more specifically about 10 to 70 캜, but the present disclosure is not limited thereto.

According to an illustrative embodiment, for polymerization, initiators such as ammonium persulfate, potassium persulfate, sodium persulfate, lithium persulfate, ammonium bisulfate, sodium bisulfate; Azobis (1-methylbutyronitrile-3-sodium sulfonate), 4,4-azobis (4-cyanovaleric acid), etc. may be used alone or in combination, And the present disclosure is not limited thereto.

However, in the case of the model provided according to the specific example of the present disclosure, it can be assumed that the type and amount of the initiator are not taken into consideration. This is because the effect of the initiator on the swelling behavior of the hydrogel, .

In an exemplary embodiment, anionic surfactants such as alkyl and alkylaryl polyoxyethylene ethers and surfactants such as alkylaryl formaldehyde condensed polyoxyethylene ethers, ether type, glycerin ester polyoxyethylene ethers, sorbitan esters, Polyoxyethylene ethers, and polyoxyethylene ethers of sorbitol esters; esters such as polyethylene glycol fatty acid esters, glycerin esters, and sorbitan esters; and fatty acid alkanolamides such as polyoxyethylene alkylamines, Amide type (small size), and the like. Typically, TWEEN 20 (polyethylene glycol sorbitan monolaurate) and the like can be used.

According to an exemplary embodiment, the hydrogel polymer may not be completely excluded, for example, an ionic hydrogel, but may be specifically a nonionic hydrogel. For example, the polymer constituting the hydrogel may be selected from the group consisting of poly (N-isopropylacrylamide), poly (N-isopropylmethacrylate), PNNPAM (poly (N, N-propylacrylamide) 2-methoxyethoxy) ethyl methacrylate), PNMIPA (poly (N-2-methoxyisopropylacrylamide)), PNDEA (poly (N, N-diethylacrylamide), PNDMA N-acryloylglycin), PVCL (poly (vinylcaprolactam)), PNTBA (poly-N-tert-butylacrylamide), PNCPA (NIPA-co-ENAG), P (NIPA-co-NDMA) or a combination thereof.

In this regard, the types of various exemplary hydrogels (particularly nonionic hydrogels) are shown in Table 1 below.

According to an illustrative embodiment, the hydrogel may be a particulate hydrogel, typically having a particle size in the range of several hundreds of microns to thousands of microns. For example, the size of the particle-like hydrogel may be in the range of, for example, about 100 to 8000 mu m, specifically about 300 to 5000 mu m, more specifically about 500 to 3000 mu m, no. According to another exemplary embodiment, the hydrogel may be a bulk-phase hydrogel. In addition, the absorption capacity of the hydrogel may be, for example, at least about 10 g / g, specifically at least about 25 g / g, more specifically about 50 g / g, for an aqueous medium such as water have.

FIG. 1 schematically shows a process of calculating the degree of swelling of a hydrogel through a group contribution method in one embodiment of the present disclosure.

) 및 겔 자체의 가교 구조를 고려한(

)의 2개의 항의 합, 즉

으로 나타낼 수 있다(

는 헬름홀츠 에너지임).As described above, the hydrogel polymer is a three-dimensional structure exhibiting elasticity due to a crosslinked structure, and swells or shrinks due to various external factors. The swelling phenomenon of the hydrogel may vary depending on the crosslinking structure of the gel represented by the content of the crosslinking agent in the gel and the type and composition of the liquid medium (solvent or solution) surrounding the gel. Therefore, the thermodynamic simulation of the swelling phenomenon of the hydrogel is based on the interaction between the polymer forming the gel and the liquid medium

) And considering the cross-linking structure of the gel itself

), I.e.,

Can be expressed as

Is Helmholtz Energy).

는 후술하는 바와 같이 수학식 6으로 표현되는 혼합 헬름홀츠 에너지(또는 MDL), 그리고

은 후술하는 바와 같이 수학식 8로 표현되는 Flory-Rehner 이론을 적용할 수 있다.The two terms can be given as thermodynamic models based on lattice theory,

(Or MDL) represented by Equation (6) as described below, and

The Flory-Rehner theory expressed by Equation (8) can be applied as described later.

)를 결정(산출)한다. 그 다음, 하이드로겔을 구성하는 고분자 단량체의 분자 구조와 그룹 파라미터를 이용하여 후술하는 수학식 13 또는 14를 적용함으로써 수학식 7의 에너지 파라미터(

)를 산출한다. 이와 같이,

및

를 구하면 화학적 포텐셜을 구하기 위한 수학식 10에 대입하여 팽윤도를 산출할 수 있다. 이하에서는 하이드로겔의 팽윤도를 구하기 위한 일련의 단계를 보다 상세히 설명한다.Through this prediction model, as shown in the figure, the average number of elastic active chains between crosslinking points or the crosslinking point length (

) Is calculated (calculated). Next, by applying the following equation (13) or (14) using the molecular structure and the group parameter of the polymer monomer constituting the hydrogel, the energy parameter

). like this,

And

, The degree of swelling can be calculated by substituting in Equation (10) for obtaining the chemical potential. Hereinafter, a series of steps for determining the degree of swelling of the hydrogel will be described in more detail.

Thermodynamic model

Thermodynamic models for hydrogels (specifically nonionic hydrogel) systems typically include mixed contributions (e.g., between hydrogels and solvent) and elastic contributions (e.g., elastic contributions taking into account cross-linking etc.). Thus, the net change in Helmholtz energy can be expressed as the sum of the two contributions as shown in Equation (1) below.

[Equation 1]

In the above formula, superscript " mix " and " el " mean mixed contributions and elastic contributions. Mixture contributions are defined by intermolecular interactions between polymers and infinite chain lengths of unmyelinated polymers and solvents under the same conditions as gel networks.

The chemical potential of component i can be expressed by the following equation (2).

&Quot; (2) "

Further, the equilibrium condition for the hydrogel / solvent system can be expressed by the following equation (3).

&Quot; (3) "

In the above formula, the superscripts " in " and " out " refer to the inside of the gel and the outside of the gel, respectively.

- Mixed contributions

In the conventional MDL model (J. S. Oh, Y. C. Bae, Polymer 1998, 39, 1149-1154), the Helmholtz energy of the mixture can be expressed by the following equation (4).

&Quot; (4) "

)의 함수이고, 그리고 사슬 길이(r _i )는 하기 수학식 5로 표시된다.Is the volume fraction of the above formula, φ _i is component i, a _{i, j} is a reduced exchange of energy (

), And the chain length ( r _i ) is expressed by the following equation (5).

&Quot; (5) "

및

는 각각 격자 고분자 시뮬레이션 데이터를 사슬 길이 r ₁ =1 및 r ₂ =100와 비교함으로써 결정된다. 그러나, 보편 상수는 사슬 길이에 대한 의존성이 크고, r _i 가 증가할수록 특정 값으로 수렴한다. 그러나, 하이드로겔 시스템에 대한 보편 상수 값은 혼합 기여가 용매와 무한한 사슬 길이를 갖는 선형 고분자와 용매 간의 상호작용에 의하여 결정되므로, 시뮬레이션 데이터로부터 도출하기는 곤란하다. 따라서, 하이드로겔 시스템에 대하여 수학적으로 최적화된 모델을 도출하기 위하여, 보편 상수

및

는 각각 0.3 및 0으로 변경될 수 있다(보편 상수의 결정 방법은 후술함).Universal constant

And

Are determined by comparing the lattice polymer simulation data with the chain lengths r ₁ = 1 and r ₂ = 100, respectively. However, the universal constant has a large dependence on the chain length, and converges to a specific value as r _i increases. However, the universal constant value for the hydrogel system is difficult to deduce from the simulation data because the mixing contribution is determined by the interaction between the solvent and the linear polymer having an infinite chain length and the solvent. Thus, to derive a mathematically optimized model for a hydrogel system, a universal constant

And

Can be changed to 0.3 and 0, respectively (a method of determining the universal constant will be described later).

Although the universal constant has quasi-empirical properties, the resulting equation for mixed Helmholtz energy better matches the experimental swelling curve than the conventional MDL model and has a simpler mathematical form. As a result, the mixed Helmholtz energy is expressed by the following equation (6).

 &Quot; (6) "

- Interchange energy parameters for specific interactions

)의 온도 의존성은 공지된 문헌(Lee et al., Macromolecules 2014, 47, 8394-8403)에 언급된 바와 같이 S자형(sigmoidal form)을 나타낸다. 그러나, 상기 문헌에서 제시된 표현은 실험 데이터와 어느 정도 부합되기는 하나, 하이드로겔 시스템을 기술하기 위하여 5개의 조정가능한 파라미터를 갖는 준-경험적 특성을 갖고 있다. 이를 위하여, 본 개시 내용의 구체예에서는 하기 수학식 7과 같은 하이드로겔 시스템 내 상호교환 에너지 파라미터(

)에 대한 택일적 표현을 제공한다.The mathematical expression of certain interactions (e. G., Hydrogen bonding) plays a critical role in describing the swelling behavior of the hydrogel system. Interchange Energy Parameters in Hydrogel Systems (

) Represents the sigmoidal form as mentioned in the well-known literature (Lee et al., Macromolecules 2014, 47, 8394-8403). However, the expressions presented in this document have quasi-empirical properties with five adjustable parameters to describe the hydrogel system, although to some extent matched the experimental data. To this end, in an embodiment of the present disclosure, an interchange energy parameter (< RTI ID = 0.0 >

). ≪ / RTI >

&Quot; (7) "

Where [epsilon] ^* and [delta] [epsilon] ^* are energy parameters for general interaction and specific interaction, respectively, and superscripts " H " and " S " respectively indicate enthalpy contribution and entropy contribution, respectively.

)에 대한 구체적인 유도는 후술하기로 한다.Energy parameter (

) Will be described later.

- elastic contribution

The elastic contribution can be expressed by the following equation (8) by improving the Flory-Rehner model.

&Quot; (8) "

Where f is the functionality of the crosslinking agent in the polymer gel network and corresponds to 4 assuming a complete 4-functional network. ? _g and ? _o are the volume fractions of the polymer gel in the swollen state and the reference state, respectively.

)는 하기 수학식 9와 같이 표시될 수 있다.In order to reduce the number of adjustable parameters, the polymer gel in the reference state is completely dried, and φ _o is set to 1. Therefore, the swelling ratio is 1 / ? _G. The average number of elastic active chains between crosslinking points (the number of elastically active chains between cross-linking sites;

) Can be expressed by the following equation (9).

  &Quot; (9) "

는 하이드로겔 내부(겔 네트워크 내부)의 가교제(cross-linker)의 몰 분율이고,

및

는 각각 하이드로겔 고분자의 반복 단위 및 용매의 반 데르 발스 체적이다. In this formula,

Is the mole fraction of the cross-linker inside the hydrogel (inside the gel network)

And

Are the van der Waals volumes of the repeating units of the hydrogel polymer and the solvent, respectively.

가 완전히 실험 조건에 의하여 결정되고, 따라서 조정가능한 파라미터가 아니라는 것이다.At this point,

Is completely determined by the experimental conditions and is therefore not an adjustable parameter.

The net change in Helmholtz energy for the hydrogel system can be obtained by substituting equations (6) and (8) into equation (1), where the chemical potential of the solvent in the gel network is given by:

&Quot; (10) "

는 보편적 파라미터(universal parameter)이다.In this formula,

Is a universal parameter.

으로부터 산출되는 바, 이는 하이드로겔 외부에서 용매의 화학적 포텐셜이 0이기 때문이다.Then, the swelling equilibrium curve

, Because the chemical potential of the solvent outside the hydrogel is zero.

Group Contribution Act

The basic concept of the group contribution method is to predict the behavior of other systems by using existing experimental data (ie swelling data) without any additional experimental data.

- Group parameter

 According to one embodiment, the repeating units constituting the hydrogel polymer are separated and identified by functional groups. The size parameters of the individual functionalities constituting the hydrogel thus specified are reported in A. Bondi, Physical Properties of Molecular Crystals, Liquids and Glasses, Wiley: New York, 1968 Chapter 4, pp 74-75 Can be derived from the van der Waals group volume. Table 2 below shows the size parameters of the functional groups constituting the exemplary hydrogels.

Each of the energy parameters (ε ^* , δε ^* , δε ^H, and δε ^S ) described in Equation (7) can be expressed as a pair-interaction group parameter and expressed as Equation (12).

&Quot; (12) "

In the above equation ,? _K and ? _L are the volume fraction of the functional group ( k ) in the polymer and the volume fraction of the functional group ( l ) in the solvent, respectively. Considering only the hydrogel system, θ _l can be set to 1 so as to simply display the equation 12 to the equation (13).

&Quot; (13) "

In the case of the copolymer gel system, the mole fraction of the comonomer is included and can be expressed as Equation (14) below.

&Quot; (14) "

는 단량체 i 내 관능기(k)의 체적 분율이다.Where x _i is the mole fraction of monomer i in the hydrogel copolymer,

Is the volume fraction of the functional group ( k ) in the monomer i .

The interaction energy parameter for each functional group can be obtained from the swelling experimental data by the following procedure.

(i) Step 1

를 결정한다.From the experimental conditions (including the molar fraction of the cross-linking agent used in the gel synthesis process) from equation (9)

.

(ii) Step 2

을 수학식 10에 대입하여 상호작용 에너지-온도 쌍

을 산출한다.Experimental data pair

Into the equation (10) to calculate the interaction energy-temperature pair

.

(iii) Step 3

를 이용하여, 수학식 7 내에서의 그룹 파라미터들을 단계 2로부터 얻어진

로 피팅시킨다.Objective function

, The group parameters in equation (7) are obtained from step (2)

.

The interaction parameters between the water and the functional groups can be represented as shown in Table 3 below.

)를 구하여 전술한 수학식 10에 대입하고

인 조건 하에서 팽윤도, 즉 1/φ _g 를 구할 수 있다.As described above, the interaction energy parameter between the water and the individual functional groups constituting the hydrogel is obtained. From the equation (7), the chemical potential energy parameter

) Is substituted into the above-mentioned equation (10)

The swelling degree, that is, 1 / φ _g , can be obtained.

On the other hand, according to another embodiment of the present disclosure, a method for predicting the swelling behavior of a salt-containing hydrogel is provided.

When a salt is incorporated or added into the hydrogel, it causes a change in the interaction between the solvent and the gel network, which serves as a factor to change the swelling behavior of the hydrogel. In particular, strong electrostatic interactions are caused by ions, which can disrupt the stable gel structure by disrupting the regular structure of water around the hydrophobic portion of the polymer gel. Representative examples of such salts include sodium salts (for example, NaCl, NaBr, NaI and the like), ammonium salts, potassium salts, lithium salts, combinations thereof and the like. In addition, the amount (addition amount) of the salt in the hydrogel polymer may be, for example, up to about 3 M, specifically about 0.1 to 2 M, more specifically about 0.3 to 1.5 M.

According to exemplary embodiments, the salt-containing hydrogel may be a bulk-phase hydrogel because, in the case of microgels, the stability of the gel may be lowered when the concentration of the salt is increased.

In addition, the volumetric phase transition temperature decreases with the addition of salt, and the change is generally linear with salt concentration. Although the salt-responsive swelling behavior of the charged gel can be described by the theory described in the literature (for example, FG Donnan, Chem. Rev. 1924, 1, 73-90), hydrogels On hydrogels) due to the limitations of conventional conventional theories.

Therefore, in the above specific example, a salt-specific parameter is introduced into the interaction energy parameter expression for the purpose of solving this problem, which can be expressed by the following equation (15).

&Quot; (15) "

Where ε ^* and δε ^* are energy parameters for general interactions and specific interactions, respectively, δε ^salt / k is a salt-specific interaction parameter, C is the salt concentration in mol / L , And superscripts " H " and " S " denote enthalpy contribution and entropy contribution, respectively.

How to determine the universal parameter

The universal parameters in the chemical formal equation according to Equation 10 described above can be obtained as follows.

In the initial MDL model and the Flory-Rehner model, the chemical potential of the solvent in the two-component hydrogel system can be represented by the following equation (16).

&Quot; (16) "

=0.1415 및

=1,7986로 결정된다. 이후, 산술 조작을 통하여 수학식 16은 하기 수학식 17과 같이 표현될 수 있다.By fitting the lattice polymer simulation data using the chain lengths r ₁ = 1 and r ₂ = 100,

= 0.1415 and

= 1,7986. Then, through the arithmetic operation, the expression (16) can be expressed as the following expression (17).

&Quot; (17) "

In this formula,

.

.

The answer of the above-mentioned equation (17) can be expressed by the following equation (18).

&Quot; (18) "

가 100이고 φ _{g 0}이 1인 경우, 산출된 팽윤도는 17.66을 초과할 수 없음). 또한, 초기 MDL 모델 내에서의 보편적 파라미터(상수)는 무한한 사슬 길이를 갖는 고분자라는 가정에 위배된다. 이러한 결함을 해소하기 위하여,

는 0으로 설정되고

는 0.3으로 설정된다. 상기 값을 이용하여 수학식 17은 전술한 수학식 10과 같이 선형 방정식으로 나타낼 수 있게 된다. Equation (18) implies an imaginary term when the discriminant is negative, which means that in certain cases the initial MDL model can not adequately describe the swelling curve (e.g.,

Is 100 and φ _{g 0} is 1, the calculated degree of swelling can not exceed 17.66). In addition, the universal parameter (constant) in the initial MDL model is contrary to the assumption that the polymer has an infinite chain length. In order to solve such a defect,

Is set to zero

Is set to 0.3. Using Equation (17), Equation (17) can be expressed as a linear equation as shown in Equation (10).

Induction of interaction energy parameters

According to Sanchez et al., The interaction energy parameter is expressed as: " (19) "

&Quot; (19) "

Wherein, ε / k T and δε / T k is a non-specific and specific interaction parameter, respectively.

The fraction f of the specific interaction between the polymer segment and the solvent is expressed by the following equation (20).

&Quot; (20) "

Where g is the degeneracy ratio of the two states.

At this time, it can be assumed that g is equal to 1 in order to reduce the number of adjustable parameters in the presented model. By introducing an entropy contribution and an energy contribution to (19) with respect to the energy parameter, Equation (19) can be expressed by Equation (21).

&Quot; (21) "

The mathematical form of the energy parameter can be obtained by simplifying the first term of Equation (21). Then, the final shape of the interaction energy parameter through a mathematical operation can be expressed by Equation (7). However, for the convenience of understanding, Equation (7) can be rewritten as Equation (22).

&Quot; (22) "

As mentioned above, the accuracy of the group contribution method to predict the swelling behavior of the hydro gel system depends on the thermodynamic model. However, since the universal constants in the MDL model presented in the prior art are not suitable for application to hydrogels, embodiments of the present disclosure introduce new expressions of interaction energy parameters based on association theory such as Sanchez et al. At this time, the group interaction parameters are determined by the experimental swelling curve from both the homopolymer and copolymer hydrogel systems. As a result, a predicted value corresponding to the experimental data can be obtained. Furthermore, in the case of salt-containing hydrogels, the salt-induced volume phase transition behavior can be calculated by introducing additional salt-specific parameters. The group contribution method presented in this disclosure is in good agreement with available experimental data and is effectively applicable to the stimulus-responsive swelling behavior of hydrogel systems.

Hereinafter, preferred embodiments of the present invention will be described in order to facilitate understanding of the present invention. However, the present invention is not limited thereto.

Example 1

Hydrogel system

end. Homopolymer hydrogel

- PNIPA gel / water system

The PNIPA hydrogel used in this example was prepared according to the method described in Y. D. Yi, K. S. Oh, Y. C. Bae, Polymer 1997, 38, 3471-3476. Specifically, NIPA (molecular weight: 113.6) commercially available from TCI Co. was recrystallized and dried in a vacuum oven for 2 days and then used as a monomer. As a crosslinking agent, N, N'-methylenebisacrylamide (BIS, molecular weight: 154.17) commercially available from TCI Co. was used after recrystallization. The molar fraction of cross-linker to total NIPA monomer was 0.0388.

A 1 wt% ammonium persulfate (APS) solution was used as an initiator and TWEEN 20 was used as a nonionic surfactant. The reaction product was subjected to precipitation polymerization at 70 DEG C for 4 hours while nitrogen blowing. At this time, deionized water distilled as a solvent was used. As a result of the polymerization, sub-micron PNIPA gel beads were obtained. The molecular structure of the PNIPA gel is shown in the following general formula (1).

[Formula 1]

As can be seen from the above general formula (1), PNIPA contains one CH ₂ group, one CONH group, one isopropyl group and one CH group. Therefore, the van der Waals volume of PNIPA is 64.13 cm3 / mol. The van der Waals volume of water is 11.44 cm3 / mol as calculated from the group contribution method of Bondi.

는 72.24(=64.13/(2·0.0388·11.44))이었다.By applying the above equation (9)

Was 72.24 (= 64.13 / (2. 0.0388.11.44)).

Other parameters were obtained as follows.

? _CH2 = 1.10.23 / 64.13 = 0.1595

? _CONH = 1.13 / 64.13 = 0.2027

? _isopropyl = 1.34.1 / 64.13 = 0.5317

? _CH = 1. 6.8 / 64.13 = 0.1060

The energy parameters were obtained as follows.

및 에너지 파라미터를 수학식 10에 대입하면, 남은 미지의 변수는 온도 및 φ _g 인 바, 일정한 온도에서 PNIPA의 팽윤도는

으로부터 얻어진다.

And the energy parameter are substituted into equation (10), the remaining unknown variables are temperature and phi _g , and the swelling degree of PNIPA at a constant temperature is

/ RTI >

- N-Substituted Polyacrylamide Gel / Water System

N-substituted polyacrylamide gels were prepared as described in the following Table 4, except that the monomers were changed, and the degree of swelling of each of them was calculated.

- Uni-polymeric gel / water systems other than N-substituted polyacrylamides

A single polymer gel / water system other than the N-substituted polyacrylamide, specifically the PNIPMA / water system, the PMEO2MA / water system and the PVCL / water system were prepared via the methods described above, except that the monomers were changed, And each degree of swelling was calculated.

I. Copolymer hydrogel

- P (NIPA-co-HEMA) gel / water system

P (NIPA-co-HEMA) hydrogel was prepared according to H. Cicek, A. Tuncel, J. Poly. Sci. Part A: Polym. Sci. 1998, 36, 527-541. At this time, the molar fraction of the cross-linking agent was 0.0177. The molecular structure of the P (NIPA-co-HEMA) gel is shown in the following general formula (2).

[Formula 2]

는 166.3941 (=67.31/(2·0.0177·11.44))이었다.As can be seen from the above general formula 2, PHEMA contains one CH ₃ group, one C group, one COO group, one OH group, and three CH ₂ groups. The reported mole fraction of HEMA monomer is 0.473. The van der Waals volume of PHEMA was 70.86 cm3 / mol and the van der Waals volume of P (NIPA-co-HEMA) was 67.31 (= 64.13.0.527 + 70.86.0473) cm3 / mol. therefore,

Was 166.3941 (= 67.31 / (2. 0.0177.11.44)).

The volume fraction of each group is as follows.

Using Equation (14),? ^* = 0.1099,?? ^* = 0.8901,?? ^H = -8350.52, and?? ^S = -26.1648.

- various copolymerized polyacrylamide gel / water systems

Various copolymerized polyacrylamide gels were prepared as described in Table 5 below, except that the monomers were changed, and the degree of swelling of each of them was calculated.

Evaluation of Swelling Behavior

end. Uni-polymer gel / water system

3A and 3B each show the swelling curve of the hydrogel system in the PNIPA / water system and the PNCPA / water system prepared above.

According to the figure, the swelling behavior of the hydrogel predicted according to the embodiment is in accordance with the swelling behavior and the high accuracy according to the experimental data. On the other hand, it can be seen that the swelling behavior of the hydrogel predicted using the conventional MDL model shows a considerable variation. In particular, while the MDL model showed a somewhat similar tendency to the experimental data for a specific hydrogel polymer system (PNCPA / water system) (Fig. 3b), a significantly larger deviation for the other hydrogel polymer systems (PNIPA / water system) (Fig. 3A). However, it has been found that prediction models according to the embodiments can provide high accuracy prediction results for various single polymer / water systems.

On the other hand, it has been reported that the phase equilibrium behavior and heat-sensitivity of the linear polymer depend on the substituted functional groups (R1 and R2) (Y. Cao, XX Zhu, J. Luo, H. Liu, Macromolecules 2007, 6481-6488). For example, increasing the hydrophobicity of functional groups increases the degree to which the chain of polymers is costly in water. As the hydrophobic functional groups reduce the swelling area, the volumetric phase transfer behavior of the hydrogel also shows a similar tendency.

In this regard, swelling behavior was predicted for the various homopolymer (N-substituted polyacrylamide) gel / water systems described in Table 4 and compared to experimental data and shown in FIG.

According to the figure, the volumetric phase transition temperature of the polymer gel system depends on the hydrophilicity of the substituted functional groups: PNMIPA> PNCPA> PNIPA> PNDEA> PNNPAM (methoxyisopropyl) cyclopropyl> isopropyl iso-propyl> ethyl groups> n-propyl).

Particularly, as shown in the figure, the swelling behavior of the hydrogels predicted according to the examples was in good agreement with the actual experimental data. Thus, it has been found that the predictive model according to embodiments of the present disclosure accurately describes the effect of functional groups on the swelling behavior of a single polymer gel / water system.

On the other hand, the predicted results and experimental results on the swelling behavior of each of the PNIPMA / water system, the PMEO2MA / water system and the PVCL / water system, which are single polymer gel / water systems other than N-substituted polyacrylamide, are shown in FIGS. 5A to 5C Respectively.

As can be seen from the figure, it can be seen that the swelling behavior of the hydrogels predicted according to the examples is in good agreement with the experimental data.

I. Copolymer gel / water system

Besides the substitution of functional groups, the hydrophobicity of the homopolymer gel network can be changed by copolymerization, and when the fraction of the hydrophobic comonomer is increased, the swelling area is reduced. In this example, experiments were conducted to control the swelling behavior of N-alkyl acrylamide gels through copolymerization with hydrophilic or hydrophobic comonomers. The swelling behavior of the copolymer hydrogel system shown in Table 5 was measured, and the results are shown in FIGS. 6A to 6C and FIG. 7. FIG.

6A-6C are swelling curves of a copolymer hydrogel system with hydrophobic comonomers, wherein P (NIPA-co-NTBA) / water system, P (NIPA-co-ENAG) co-HEMA) / water system. In addition, the mole fractions of comonomers incorporated into each of the above figures are shown.

According to the figure, the swelling behavior data and the experimental data calculated using the model according to the embodiment were met with high accuracy. Also, the volumetric phase transition temperature decreased with increasing fraction of comonomer.

Figure 7 is the swelling curve of a copolymer hydrogel system with hydrophilic comonomer (NDMA), which describes the mole fraction of entrained comonomer.

According to the figure, as the molar fraction of the hydrophilic comonomer NDMA increases, the volume phase transition temperature increases, because the hydrophilic comonomer forms a favorable interaction between the copolymer gel and water.

Example 2

In this example, various salts (NaCl, NaBr, and NaI) were added to the PNIPA prepared in Example 1 to examine the effect of salt-mixing on the volume phase transition behavior of the hydrogel. According to the examples, the swelling behavior and the experimental data of the predicted hydrogel system were compared by introducing Equation (15) instead of Equation (7). In this regard, Figures 8a-8c are swelling curves of a salt-containing PNIPA hydrogel system, respectively, referring to PNIPA / water / NaCl system, PNIPA / water / NaBr system and PNIPA / water / NaI system, respectively. At this time, the obtained group parameters?? ^NaCl / k,?? ^NaBr / k and?? ^NaI / k were -0.7865, -0.4971, and -0.2823, respectively.

As shown in the figure, the model predicted according to the embodiment is in good agreement with the experimental data, which means that it can provide a good predictive model by introducing only one additional parameter. In addition, the volumetric phase transition temperature decreased as the amount of salt added increased, and this change was found to be almost linear in salt concentration.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims.

Claims (17)

As a method for predicting the swelling behavior of a hydrogel,
a) separating and identifying the repeating units constituting the hydrogel polymer by functional groups;
b) calculating an average number of elastically active chains between cross-linking points according to the van der Waals volume measured experimentally for each of the specified functional groups according to the following equation (9) linking sites;

),
&Quot; (9) "

In this formula,

Is the mole fraction of the cross-linker in the hydrogel,

And

Is the van der Waals volume of the repeating unit and solvent of the hydrogel polymer, respectively;
c) Applying the group contribution method based on ε ^* , δε ^* , δε ^H and δε ^S experimentally obtained for each of the above specified functional groups,

(7), < / RTI >
&Quot; (7) "

Where [epsilon] ^* and [delta] [epsilon] ^* are energy parameters for general interaction and specific interaction, respectively, superscripts " H " and " S " indicating enthalpy contribution and entropy contribution, respectively; And
The determined

And

(Swelling ratio: 1) by calculating the volume fraction ( ? _G ) of the hydrogel in a swollen state at a fixed temperature (T) by substituting the chemical potential of the solvent in the hydrogel network into the following equation / [ phi] _g )
&Quot; (10) "

In this formula,

Is set to 0.3 as a universal parameter, and

Lt; / RTI >
≪ / RTI > As a method for predicting the swelling behavior of a salt-containing hydrogel,
a) separating and identifying the repeating units constituting the salt-containing hydrogel polymer by functional groups;
b) calculating an average number of elastically active chains between cross-linking points according to the van der Waals volume measured experimentally for each of the specified functional groups according to the following equation (9) linking sites;

),
&Quot; (9) "

In this formula,

Is the mole fraction of the cross-linker in the hydrogel,

And

Is the van der Waals volume of the repeating unit and solvent of the hydrogel polymer, respectively;
c) Applying the group contribution method based on ε ^* , δε ^* , δε ^H and δε ^S experimentally obtained for each of the above specified functional groups,

(15), < / RTI >
&Quot; (15) "

Where ε ^* and δε ^* are energy parameters for general interactions and specific interactions, respectively, δε ^salt / k is a salt-specific interaction parameter, C is the salt concentration in mol / L , And superscripts " H " and " S " respectively indicate enthalpy contribution and entropy contribution; And
The determined

And

(Swelling ratio: 1) by calculating the volume fraction ( ? _G ) of the hydrogel in a swollen state at a fixed temperature (T) by substituting the chemical potential of the solvent in the hydrogel network into the following equation / [ phi] _g )
&Quot; (10) "

In this formula,

Is set to 0.3 as a universal parameter, and

Lt; / RTI >
≪ / RTI > According to claim 1 or 2, wherein the ε ^*, δε ^*, δε ^H and δε ^S each of which characterized in that determined in accordance with, the following equation 11 and 13 when the hydrogel polymer is a homopolymer:
&Quot; (11) "

Wherein V _i is the volume of the molecule i ,

Is the number of functional groups ( k ) in the molecule i , and

Is the volume of the functional group ( k )
&Quot; (13) "

Wherein R, θ _k being the volume fraction of the hydrogel homopolymer within the functional group (k). According to claim 1 or 2, wherein the ε ^*, δε ^*, δε δε ^H and ^S are each characterized in that the determination according to the following equation (11) and 14 in a case where the hydrogel polymer is a copolymer of:
&Quot; (11) "

Wherein V _i is the volume of the molecule i ,

Is the number of functional groups ( k ) in the molecule i , and

Is the volume of the functional group ( k )
&Quot; (14) "

Where x _i is the mole fraction of monomer i in the hydrogel copolymer,

Is the volume fraction of the functional group ( k ) in the monomer i . 3. The method according to claim 1 or 2, wherein the hydrogel is a non-ionic hydrogel. The method of claim 1 or 2, wherein the solvent is water,

Is set to 11.44 cm < 3 > / mol. delete 3. The method according to claim 1 or 2, wherein the hydrogel polymer is a homopolymer or a copolymer. 3. The method according to claim 1 or 2, wherein the hydrogel polymer is prepared by polymerizing a monomer with addition of a crosslinking agent. The method of claim 9, wherein the monomer is selected from the group consisting of N-butyl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) (meth) acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate Acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, 2- (2-methoxyethoxy) ethylmethacrylate, (2-methoxyethoxy) ethyl methacrylate, N- (2-hydroxyethyl) acrylamide, N-methyl acrylamide, N- N-isopropylacrylamide, N-tert-butyl Acrylamide, N, N-dimethylacrylamide (NDMA), N, N-diethylacrylamide (NDMA), N-butoxymethyl acrylamide, N-methoxymethyl acrylamide N-methoxymethyl acrylamide, N-methoxyisopropyl acrylamide, N-cyclopropylacrylamide, ethyl-N-acryloylglycine, Vinyl caprolactam, N-methoxymethyl methacrylamide, 2-acrylamidoglycolic acid or 2-carboxyethyl acrylate, 2-hydroxy-5-methoxyacetophenone, 2-hydroxyethyl disulfide, or a combination thereof. The polymer of claim 8, wherein the polymer constituting the hydrogel is selected from the group consisting of poly (N-isopropylacrylamide), poly (N-isopropylmethacrylate), PNNPAM (poly (N, N-propylacrylamide) N-diethylacrylamide), PNDMA (Poly (N, N-dimethylacrylamide)), PENAG (poly (N-dimethylacrylamide) Poly (N-acryloylglycine), PVCL (poly (vinylcaprolactam)), PNTBA (poly (N-tert-butylacrylamide) NIPA-co-NTBA), P (NIPA-co-HEMA), P (NIPA-co-ENAG), P (NIPA-co-NDMA) or a combination thereof. [10] The method of claim 9, wherein the content of the cross-linking agent for the entire monomers constituting the hydrogel polymer is selected from the range of 0.1 to 10 mol%. 2. The method of claim 1, wherein the hydrogel is a particulate hydrogel and the particle size of the particulate hydrogel is in the range of 100 to 8000 [mu] m. 3. The method of claim 2, wherein the hydrogel is a bulk hydrogel. 3. The method of claim 2, wherein the salt is a sodium salt, an ammonium salt, a potassium salt, a lithium salt or a combination thereof. 16. The method of claim 15, wherein the salt in the hydrogel polymer is incorporated up to 3 M. The method according to claim 1 or 2, wherein the absorption capacity of the hydrogel is at least 10 g / g based on the aqueous medium.

Images