Effects of microcrystallites on swelling behavior in chemically crosslinked poly(vinyl alcohol) gels

We report the swelling ratio and network structure of a poly(vinyl alcohol) (PVA) gel chemically crosslinked by glutaraldehyde with different degrees of crosslinks. Microcrystallites were formed in a chemical PVA gel during a drying process and were confirmed by X‐Ray diffraction (XRD) measurements and Fourier transform infrared (FTIR) spectroscopy. The formation of microcrystallites in the dried gels was suppressed by increasing the degrees of chemical crosslinks. When the dried samples were immersed in pure water at 25 °C, the swelling ratio depended on the degree of chemical crosslinks resulting from the destruction of physical crosslinks by microcrystallites. On the other hand, when the dried samples were immersed in a poor solvent of a mixture of dimethyl sulfoxide and water at 8 °C, the gels did not swell and stayed in the collapsed state. Starting from the collapsed state, the equilibrium swelling ratios were measured while the temperature was increased to 90 °C and then decreased to 8 °C. As a result, irreversible swelling behaviors were observed for all gels with different degrees of crosslinks, which were attributed to the destruction of microcrystallites. The swelling behavior is discussed in terms of the formation and destruction of additional physical crosslinks in the chemical PVA gels. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011     

Physicochemical characterization of chemical hydrogels based on PVA

In this paper, we report on the physicochemical characterization of hydrogels recently obtained by crosslinking poly (vinylalcohol), PVA, with telechelic PVA (telPVA, bearing terminal aldehydic groups) via acetalization in aqueous solution. These gels were studied by equilibrium swelling, compression modulus measurements, and proton relaxometry experiments. Swelling and compression modulus data allow to estimate the average molecular weight of PVA chain between crosslinks, the average mesh size of the networks, and the polymer–solvent interaction parameter χ₁. The average mesh size of PVA‐telPVA compares well with domain dimensions of diffusionally confined water as detected by NMR relaxometry. Proton relaxometry also showed different network domains in which water is compartmentalized, indicating a complex heterogeneity. The study of the temperature behavior of the nuclear spin–spin relaxation times of the confined water was also considered. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1225–1233, 1999     

Facile synthesis of amphiphilic gels by frontal free‐radical polymerization

We report a new facile strategy for quickly synthesizing poly(2‐hydroxyethyl acrylate‐co‐vinyl versatate) amphiphilic gels with excellent physicochemical properties by frontal free‐radical polymerization. The appropriate amounts of 2‐hydroxyethyl acrylate, vinyl versatate (VeoVa 9) and ammonium persulfate initiator were mixed together at ambient temperature in the presence of N‐methyl‐2‐pyrrolidone as the solvent medium. Frontal polymerization (FP) was initiated by heating the wall of the tube with a soldering iron. Once initiated, no further energy was required for the polymerization to occur. The dependence of the front velocity and front temperature on the initiator concentration was investigated. The front temperatures were between 132 and 157 °C, depending on the initiator concentration. The morphology, swelling rate, and swelling behavior of amphiphilic gels prepared via FP were comparatively investigated on the basis of scanning electron microscopy, water contact angle, and swelling measurements. Results show that the amphiphilic gels prepared via FP behave with good swelling capacity both in water and organic solvents. The FP can be exploited as an alternative means for synthesis of amphiphilic gels with additional advantages of fast and efficient way. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 823–831, 2010     

Swelling of poly(N-isopropylacrylamide) gels in water-aprotic solvent mixtures

The swelling volume of poly(N-isopropylacrylamide) (PIPAAm) gel in aprotic solvents (acetonitrile (AcN)-, tetrahydrofuran (THF)-, 1,4-dioxane (DO)- and dimethylsulfoxide (DMSO))-water mixtures was measured at 25°C. The gel swollen in water shrank first and then reswelled with addition of the aprotic solvents. At an intermediate mole fraction (XDMSO) range of DMSO-water mixtures, the gel demonstrated a reentrant swelling phenomenon the hydrated gel shrank first on addition of a small amount of solvent, showed a typical wide reentrant transition, and gradually reswelled in the range near pure solvent. On the other hand, the gels in AcN-, THF-, and DO-water mixtures demonstrated a reentrant-convex swelling phenomenon: the gels reswelled after a reentrant phase transition in low Xorg (XAcN, XTHF and XDO), showed a maximum swelling in the intermediate Xorg region, and shrank again gradually in the high Xorg region. Such a swelling behavior of the gel was interpreted by correlating with solution properties of the aqueous aprotic solvent mixtures.The strength of hydrogen bonding around amide groups of the homopolymer was examined in pure solvents (water, THF, and DMSO) and in all proportion of aqueous THF to observe the relation with swelling behavior of gel by spectrum analysis of the amide I and II bands of Fourier Transform Infrared Spectroscopy (FT-IR). The swelling properties of gels in solvents and the aqueous mixtures were well correlated with the peak shifts of amide groups of the homopolymer.     

Probing potential medium effects on phosphate ester bonds using 18O isotope shifts on 31P NMR

Dipolar aprotic cosolvents, such as DMSO and acetonitrile, accelerate the rates of hydrolysis of phosphate monoester dianions. It has been speculated that the rate acceleration arises from the disruption of hydrogen bonding to the phosphoryl group. An aqueous solvation shell can stabilize the dianionic phosphoryl group by forming hydrogen bonds to the phosphoryl oxygens, whereas solvents such as DMSO are incapable of forming such bonds. It has been proposed that the loss of stabilization could result in a weakened P-OR ester bond, contributing to the observed faster rate of hydrolysis. Computational results support this notion. We have used the 18O-induced perturbation to the 31P chemical shift to ascertain whether solvent changes result in alterations to the P-O(R) bond. We have studied 16O18O-labeled methyl, ethyl, phenyl, p-nitrophenyl, diethyl p-nitrophenyl, triphenyl, and di-tert-butyl ethyl phosphate in the solvents water, methanol, chloroform, acetonitrile, dioxane, and DMSO. The results suggest no significant solvent-induced weakening of the phosphate ester bonds in any of the solvents tested, and this is unlikely to be a significant source for the acceleration of hydrolysis in mixed solvents.     

Specific swelling behaviors of alkali‐metal poly(styrene sulfonate) gels in aqueous solvent mixtures

Counterion‐ and solvent‐specific swelling behaviors were investigated for alkali‐metal poly(styrene sulfonate) (PSSM) gels having different degrees of sulfonation in aqueous organic solvent mixtures [water plus methanol, ethanol, 2‐propyl alcohol, t‐butyl alcohol, dimethyl sulfoxide (DMSO), acetone, acetonitrile, tetrahydrofuran, or dioxane]. With an increasing organic solvent concentration, most gel systems, except for DMSO, showed a volume phase transition. The transition abruptly occurred without significant deswelling in the lower solvent concentration region. Such swelling behavior contrasted with that of other common charged gel systems, including alkali‐metal polyacrylate (PAAM) gels, which showed gel collapse after gradual deswelling with an increasing organic solvent concentration. The dielectric constant at the critical transition point (D_cr) for most mixed solvent systems decreased in the order of PSSK ≥ PSSCs ≥ PSSNa > PSSLi; that is, larger counterion systems were favorable for the transition. The counterion specificity also contrasted with our previous results for PAAM gels: PAANa > PAAK > PAALi ～ PAACs. On the other hand, the solvent specificity for the PSSM gels was similar to that for the PAAM gels; the higher the dielectric constant was of the organic solvent, the higher the D_cr value was at which the transition occurred. These specificities were examined on the basis of the solvation properties of the counterions and polymer charged groups and the solvent properties such as the Gutmann–Mayer donor number and acceptor number. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1166–1175, 2007     

Network structure and swelling behavior of poly(acrylamide/crotonic acid) hydrogels in aqueous salt solutions

Hydrogels with various ionic group contents were prepared from acrylamide and crotonic acid (CrA) monomers with 0–12.9 mol % CrA in aqueous solutions by radiation‐induced polymerization and gelation with γ rays from a ⁶⁰Co source. The volume swelling ratio of the poly(acrylamide/crotonic acid) hydrogels was investigated as a function of the pH and ionic strength of the swelling medium and the type of counterion in the swelling medium. The volume swelling ratio increased with an increase in pH and a decrease in the ionic strength. The volume swelling ratio of these hydrogels was evaluated with an equation, based on the Flory–Huggins thermodynamic theory, the James–Guth phantom network theory, and the Donnan theory of swelling of weakly charged ionic gels, that was modified here for the determination of the molecular weight between crosslinks (M_c) and the polymer–solvent interaction parameter (χ). The modified equation described very well the swelling behavior of the charged polymeric network. The same equation also provided the simultaneous measurement of these parameters for the systems investigated. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1656–1664, 2003     

Effects of repeated water exchange on the swelling behavior of poly(sodium acrylate) gels crosslinked by aluminum ions

Polyelectrolyte hydrogels, physically crosslinked by metal ions, were synthesized using poly(sodium acrylate) as the main constituent and Al ions as the crosslinker. The swelling ratio of the gel was measured whenever the solvent water was repeatedly exchanged in a constant interval. The as‐synthesized gel exhibited two relaxation processes; the gel swelled at the first stage, then shrunk very slowly at the second stage, and recovered to the initial size just after the gelation (ultimately, the gel became smaller than that). The relaxation times of both processes were found longer (exceptionally longer for the shrinking process) than the conventional collective diffusion of polymer networks. The diffused amounts of Al ions and Na counter ions in the solvent were also measured at each water exchange. The diffusion of Al ions into the solvent was found to finish when the swelling ratio took the maximum (at the end of the first stage), while Na ions continued to diffuse until the diameter became the final one (at the end of the second stage). The microscopic structural changes by the repeated water exchange were obtained by the measurements of ATR FT‐IR spectroscopy on the gels with different swelling ratios. The carboxyl groups were gradually protonated on both stages, and the formation of hydrogen bonding was accelerated on the second stage. Effects of the repeated water exchange on the swelling behavior are discussed in terms of the diffusion of Al ions into the solvent, the exchange of Na counter ions by protons, and the formation of hydrogen bonding. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 753–763, 2005     

Plasticized microporous poly(vinylidene fluoride) separators for lithium‐ion batteries. I. Swelling behavior of dense membranes with respect to a liquid electrolyte—Characterization of the swelling equilibrium

Some poly(vinylidene fluoride) (PVdF) microporous separators for lithium‐ion batteries, used in liquid organic electrolytes based on a mixture of carbonate solvents and lithium salt LiPF₆, were characterized by the study of the swelling phenomena on dense PVdF membranes. We were interested in the evolution of the swelling ratios with respect to different parameters, such as the temperature, swelling solution composition, and salt concentration. To understand PVdF behavior in microporous membranes and, therefore, to have a means of predicting its behavior with different solvent mixtures, we correlated the swelling ratios in pure solvents and in solvent mixtures to the solvent–polymer interaction parameters and solvent–solvent interaction parameters. We attempted a parametric identification of swelling curves with a very simple Flory–Huggins model with relative success. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 532–543, 2004     

Effect of poly(ethylene oxide) on the structure and properties of poly(vinyl alcohol)

To improve the drawability of poly(vinyl alcohol) (PVA) thermal products, poly(ethylene oxide) (PEO), a special resin with good flexibility, excellent lubricity, and compatibility with many resins, was applied, and the Fourier transform infrared spectroscopy, dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and wide‐angle X‐ray diffraction (WXRD) were adopted to study the hydrogen bonds, water states, thermal properties, crystal structure, and nonisothermal crystallization of modified PVA. It was found that PEO formed strong hydrogen bonds with water and PVA, thus weakened the intra‐ and inter‐hydrogen bonds of PVA, changed the aggregation states of PVA chains, and decreased its melting point and crystallinity. Moreover, the interactions among PVA, water, and PEO retarded the water evaporation and made more water remain in the system to plasticize PVA. The existence of PEO also slowed down the melt crystallization process of PVA, however, increased the nucleation points of system, thus made more and smaller spherulites formed. The weakened crystallization capability of PVA and the lubrication of PEO made PVA chains to have more mobility under the outside force and obtain high mechanical properties. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1946–1954, 2010     

The gelation rule of the polyol acetal derivatives in binary solvent mixtures

The tendency of a gelator to gel in mixed solvents is strongly correlated with its gelation behaviors in the corresponding single solvents.     

Effect of mixed solvent on solution properties and gelation behavior of poly(vinyl alcohol)

In this work, the static and dynamic light scattering measurements were used to investigate the solution properties and the aging effects on PVA/DMSO/water ternary system in dilute region at 25 °C. It was found that the phase separation and aggregate behavior occurs rapidly and obviously when DMSO mole fraction (X₁) in the solvent mixture is between 0.2 and 0.33, especially at 0.25. In this solvent composition range, a broad peak which indicates phase separation and chain aggregation can be observed from static light scattering measurement. However, when DMSO mole fraction is increased to 0.37, no such peak is present. For this ternary system, the gelation mechanism and the relationship between the phase separation behavior and the gelation of the formed physical gels were also investigated through the gelation kinetic analyses in the dilute and semi-dilute region. It is concluded that the cononsolvency effect in the dilute solution is not the sole origin that affects the phase separation, aggregation, and gelation behavior for the ternary system in a higher polymer concentration range. The hydrodynamic factors such as the higher viscosity and slower polymer chain diffusion that are resulted from higher polymer concentration should be also considered.     

Systematic design of profile control chemistry. Control of gelation of mixed poly(vinyl alcohol-co-vinylamine) crosslinked with dialdehydes

Quantitative chemistry and modeling allow us to predict the behavior of a new, environmentally friendly, non-heavy-metal-containing profile control agent as a function of well-bore conditions. We present an analysis of the kinetics and mechanism of gelation delay for dialdehyde crosslinking of mixed poly(vinyl alcohol-co-vinylamine) (PVA-VAM) copolymers. In the present system, gelation at 90–110°C takes place within minutes at pH below 6.5 and not at all at pH above 7.5 when the crosslinking agent is the acetal-protected form of the dialdehyde. We exploit this sharp pH transition by buffering to pH 9–12 and then allowing the pH to drop by in situ hydrolysis of triethyl phosphate. The fact that a pH much below 7 is not needed for gelation means that consumption of acid by carbonate rock will not be a problem as far as gelation is concerned. In fact, neutralization by rock carbonate after gelation can be expected to promote gel stability.

The kinetics of the gelation are determined by the hydrolysis kinetics of triethyl phosphate and the stability of the dialdehyde. Triethyl phosphate hydrolysis has both base-catalyzed and uncatalyzed kinetics so it is advantageous to avoid a high pH in order to extend the gel time. It is also important to avoid a high pH in order to minimize the attack of clay minerals. Gelation systems using NaOH, Na₄EDTA, and Na₃PO₄ at initial pH below 10 were developed along with a mathematical model which satisfactorily predicts their gelation times.

Spectroscopic analysis indicates that the crosslinks formed initially in the mixed polymer system are different from those in poly(vinyl alcohol) (PVA). In PVA the crosslinks are hemiacetal and 1,3-dioxane groups formed from adjacent OH groups but in PVA-VAM the amine function is more reactive and the crosslinks are hemiaminal and dihydro-1,3-oxazine groups. These are potentially more stable than the crosslinks in PVA. We have not determined the nature of the crosslinks formed after aging, but there is some evidence that the oxazine linkages convert to dioxane links. Gels stable at 110°C for 40 weeks have been demonstrated.     

吡嗪二羧酸-三聚氰胺双组分水凝胶的制备及性能

以3,6-二甲基-2,5-吡嗪二羧酸(P)和三聚氰胺(M)为组分,采用不同的摩尔比(1∶1,1∶2,1∶3)混合配制了3个样品PM11,PM12和PM13,并对其凝胶性能进行了测试.实验结果表明,PM能在水中及部分含水有机溶剂中形成稳定的凝胶,这些凝胶对酸碱具有良好的响应性能.采用扫描电子显微镜分析了3种水凝胶的微观形貌,均为纤维状的网络结构;红外光谱及紫外光谱测试结果表明氢键是形成凝胶的关键驱动力;XRD测试结果显示凝胶为层状结构.对PM12在不同pH值的水中的凝胶性能测试结果表明,在pH=3~11的范围内PM12均能形成凝胶.测试了PM12在混合溶剂中的凝胶性能,并将测试结果与混合溶剂的Hansen溶解度参数关联,以便用于分析溶剂与凝胶因子间的相互作用,所得结果亦表明氢键在凝胶形成的过程中起重要作用.     

Hydrophobic and hydrophilic aggregation of tailor‐made urethane acrylate anionomers in various solvents and their network structures

Tailor‐made urethane acrylate anionomer (UAA) chains show higher viscosity and polyelectrolyte behavior in dimethyl sulfoxide (DMSO) than in water and toluene. Water is a nonsolvent for the hydrophobic soft segment but a good solvent for the hydrophilic hard segments, so hydrophobic segments are aggregated and form particles in the water phase, resulting in a smaller viscosity. Also, the fact that the viscosity of UAA chains is lowest in toluene can be interpreted as a result of ionic aggregation due to the nonpolarity of toluene. The structures of UAA networks dramatically change with the nature of the solvents used (i.e., the interaction between the UAA chains and the solvents used changes); this is confirmed by the results of tensile property, morphology, and wide‐angle X‐ray scattering data. Ionic aggregation formed in UAA/toluene (UATG networks) and hydrophobic aggregation formed in UAA/water (UAAG networks) are locked in by a chemical crosslinking reaction and result in a greater modulus and X‐ray scattering intensity. The greater elongation and swelling ratio in methylene chloride of UATG networks prepared in a UAA/toluene solution indicates that toluene is a better solvent than DMSO for the hydrophobic segments of UAA chains. Also, the greater swelling ratio in a pH 11 buffer solution and greater modulus of UAAG networks show that water is a better solvent than DMSO for hydrophilic ionic segments. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1903–1916, 2000     

Water-induced physical gelation of organic solvents by N-(n-alkylcarbamoyl)-L-alanine amphiphiles

A series of amino acid-based gelators N-(n-alkylcarbamoyl)-L-alanine were synthesized, and their gelation abilities in a series of organic solvents were tested. No gelation was observed in pure solvents employed. All the amphiphilic molecules were found to form stable organogels in the solvents in the presence of a small amount of water, methanol, or urea. The volume of solvent gelled by a given amount of the gelator was observed to depend upon the volume of added water. The gelation behavior of the amphiphiles in a given solvent containing a known volume of water was compared. The effects of chirality and substitution on the acid group on the gelation ability were examined. Although the corresponding N-(n-tetradecylcarbamoyl)-DL-alanine was found to form only weak organogel in pure solvents, the achiral amphiphilic compound N-(n-tetradecylcarbamoyl)-β-alanine, however, did not form gel in the absence of water. The methyl ester of N-(n-tetradecylcarbamoyl)-L-alanine was also observed to form gels in the same solvents, but only in the presence of water. The organogels were characterized by several techniques, including (1)H NMR, Fourier transform IR, X-ray diffraction, and field emission scanning electron microscopy. The thermal and rheological properties of the organogels were studied. The mechanical strength of the organogel formed by N-(n-tetradecylcarbamoyl)-DL-alanine was observed to increase upon the addition of water. It was concluded that water-mediated intermolecular hydrogen-bonding interaction between amphiphiles caused formation of supramolecular self-assemblies.     

Thermodynamic analysis on the cononsolvency of poly (vinyl alcohol) in water–DMSO mixtures through the ternary interaction parameter

Isothermal phase diagrams for the semicrystalline poly (vinyl alcohol) (PVA) in solutions composed of water and dimethylsulfoxide (DMSO) was studied at 25 °C. From the observed phase behavior, PVA was soluble in either water or DMSO individually but crystallization-induced gelation and liquid–liquid demixing were observed in water–DMSO mixtures. Flory–Huggins formalism including three binary interaction parameters and one ternary interaction parameter was used to study the phenomenon of the cononsolvency, i.e. the formation of nonsolvents by mixing two solvents. The equilibrium crystallization line in the DMSO-rich region and the total calculated binodals agreed well with the measured results when a composition-dependent ternary interaction parameter was included into calculations. In contrast, calculations yielded crystallization-induced gelation in the water-rich region, but experiments indicated that PVA remained well dissolved even 1 year after preparation. The discrepancy was explained by the temperature-induced changes in the relative interaction between water and PVA. In addition, the role of the ternary interaction parameter in the cononsolvent ternary polymer systems was discussed. It was found the contribution of the ternary interaction parameter in the cononsolvent system under study is to decline the degree of the cononsolvency. The driving force for cononsolvency is the strong interaction between water and DMSO to form the stable DMSO hydrate to exclude PVA segments in the vicinity of the hydrate.     

Preparation and thermal properties of thermoplastic poly(vinyl alcohol) complexes with boronic acids

Poly(vinyl alcohol) (PVA) was converted into melt flowable derivatives by complexation with a small amount of n-butyl boronic acid (BBA) and phenyl boronic acid (PBA) in dimethylsulfoxide (DMSO), and their thermal properties were examined from a viewpoint of the melt spinning of the complexes. It was found that (1) the melting temperature of the PVA–boronic acid complexes decreases and their degradation temperature increases with increasing the boronic acid content; (2) no gelation occurs for the PVA complexes with BBA and PBA in DMSO; (3) PBA gives a larger melting-temperature depression for PVA than BBA, but the spinnability of the complexes with BBA is much better than that with PBA; and (4) the melt-molded PVA complex fibers can be easily regenerated into PVA fibers with hot water. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 3045–3050, 1998     

Solvent‐ and counterion‐specific swelling behavior of poly(acrylic acid) gels

The collapse of alkali metal poly(acrylate) (PAAM) gels was investigated for various water/organic solvent mixture systems: methanol (MeOH), ethanol (EtOH), 2‐propanol (2PrOH), t‐butanol (tBuOH), dimethyl sulfoxide (DMSO), acetonitrile (AcN), acetone, tetrahydrofuran (THF), and dioxane. In order to ascertain the counterion specificity in the swelling behavior, four kinds of alkali metal counterions were used: Li⁺, Na⁺, K⁺, and Cs⁺. Remarkable solvent and counterion specificities were observed for every counterion species and every solvent system, respectively. For example, in aqueous EtOH the dielectric constants (D_cr) at which collapse occurred were in the order PAACs < PAALi < PAAK < PAANa. On the other hand, the D_cr at which PAALi gel collapsed increased in the order tBuOH < dioxane < THF < MeOH < 2PrOH < EtOH < acetone < AcN < DMSO, where the D_cr ranged from about 39 to about 67. This was in contrast to our previous observation for a partially quaternized poly(4‐vinyl pyridine) (P4VP) gel, which collapsed in a much narrower D_cr region in similar mixed solvents. The present solvent‐ and counterion‐specific collapses are discussed on the basis of solvent properties such as the dielectric constant and Gutmann's donor number and acceptor number of a pure solvent. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2791–2800, 2000     

Novel amphiphilic network polymers consisting of nonpolar,short primary polymer chains and polar,long crosslink units: Influence of characteristic dangling chains on swelling behavior of resulting amphiphilic gels

Novel amphiphilic network polymers consisting of nonpolar, short primary polymer chains and polar, long crosslink units were prepared, and the swelling behavior of resulting amphiphilic gels is discussed by focusing on the influence of characteristic dangling chains; that is, benzyl methacrylate (BzMA) was copolymerized with tricosaethylene glycol dimethacrylate [CH₂?C(CH₃)CO(OCH₂CH₂)₂₃OCOC(CH₃)?CH₂, PEGDMA‐23] in the presence of lauryl mercaptan as a chain‐transfer agent because BzMA forms nonpolar, short primary polymer chains and PEGDMA‐23 as a crosslinker contains a polar, long poly(oxyethylene) unit. The enhanced incorporation of dangling chains into the network polymer was brought by shortening the primary polymer chain length, and copolymerization with methoxytricosaethylene glycol methacrylate, a mono‐ene counterpart of PEGDMA‐23, enforced the incorporation of flexible dangling poly(oxyethylene) chains into the network polymer, although the former dangling chains as terminal parts of primary poly(BzMA) chains were rather rigid. Then, the influence of characteristic dangling chains on the swelling behavior of amphiphilic gels was examined in mixed solvents consisting of nonpolar t‐butylbenzene and polar methanol. The profiles of the solvent‐component dependencies of the swelling ratios were characteristic of amphiphilic gels. The introduction of dangling poly(oxyethylene) chains led not only to an increased swelling ratio but also to sharpened swelling behavior of amphiphilic gels. The swelling response of amphiphilic gels was checked by changing the external solvent polarity. The dangling chains with freely mobile end segments influenced the swelling response of gels. The amphiphilic gels with less entangled, collapsed crosslink units exhibited faster swelling response than the ones with more entangled, collapsed primary polymer chains. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2192–2201, 2004