Phase transition of submicron gel beads

Hirose, Yoshiharu; Amiya, Takayuki; Hirokawa, Yoshitsugu; Tanaka, Toyoichi

doi:10.1021/ma00172a029

Cited by 166 publications

(100 citation statements)

References 5 publications

(7 reference statements)

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“…A value for the nickel(II) complex (9b) could not be measured because of the fast solubilization in water. On the other hand, iron(II) (9a) and ruthenium(III) (9d) complexes were stable and the swelling degrees could be measured without the apparent disappearance of the polymer networks by immersion in water for 24 h. These values (about [15][16][17][18] were close to each other and were in good agreement with the results of the degrees of swelling of a series of the functionalized PAEis 35 (Table II).…”

Section: The Effect Of Metal Ions On the Stability Of The Gelssupporting

confidence: 84%

See 1 more Smart Citation

Synthesis of Bipyridyl-Branched Polyoxazoline and Its Gelation by Means of Metal Coordination

Chujo

Sada

Sàegusa

1993

Polym J

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ABSTRACT:Polyoxazoline hydrogel was prepared through the coordination of the metal ions to 2,2'-bipyridyl-branched poly(N-acetylethylenimine) (PAET), which was synthesized from the partially hydrolyzed PAE! by the reaction with 3-{4-(4'-methyl-2,2'-bipyridyl)}propanoic acid in the presence of dicyclohexylcarbodiimide. Concentrated solution of 2,2'-bipyridyl-branched PAEI gave polyoxazoline gel in a good yield by the treatment with metal salts such as iron(II) sulfate, or ruthenium(III) trichloride. The resulting colored gel was highly swollen in water and stable at ambient temperature for handling. In the case of nickel(II) or cobalt(II) ions, the formed intermolecular cross-linking points via the coordination (gel state) were labile due to the rapid ligand exchange reaction of the cross-linking from intermolecular to intramolecular manner. The nickel(II) and cobalt(II) gels became soluble in a large amount of water within a few hours. A series of PAEis having varying amounts of the functional groups were prepared and subjected to the cross-linking reaction by the coordination with iron(II). The swelling degree and the stability of the gel in water depended on the content of the functional groups in the prepolymers. Water uptake was up to 56 multiples of its own weight in dry state.KEY WORDS Ring-Opening Polymerization / Polyoxazoline / Bipyridyl / Metal Coordination/ Cross-Linking/ Hydrogel / Water Swelling Property/ Cross-linking through the interaction between metal ions and polymeric ligands has been of interest for the preparation of networks. Most of these investigations focused on their physical properties in the concentrated solution. The complex formation of the metal ion with the polymer bearing the ligand groups was first claimed by Kuhn and his coworkers. 1 They discussed on the network formation from poly(vinyl alcohol) fiber by the treatment with Cu(II) salt with respect to the rheological measurement.Polymers containing carboxylic acids or hydroxyl groups such as poly(acrylic acid),2 poly{bis( carboxylatophenoxy)phosphazene}, 3 polysaccharide, 4 -6 and cellulose derivatives 7 are known to form stable hydrogels by the treatment with metal salts under the specific conditions (pH, concentration, ionic strength, etc.). A large number of ions (Ca(Il), 3 Cu(II), 2 • 3 Al(III), 3 • 7 Cr(III), 8 Ti(III), 6 • 7 and borate 4 · 5 ) are used as a cross-linking agent. These gels have been used widely in a field of industrial chemistry. However, the mechanism of the cross-linking has not been fully established. The stability and the physical properties often depend on their specific conditions for their preparations. In these systems, it is difficult to control the swelling properties and to reveal the nature of the

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Section: The Effect Of Metal Ions On the Stability Of The Gelssupporting

confidence: 84%

“…The generality of these phenomena has been investigated extensively by Tanaka's group. 17 In aqueous salts, the swelling degrees of these ionic hydrogels are known to be diminished largely in comparison with those of non-ionic hydrogels made from poly(oxyethylene) 18 or po I y( a cry !amide). 1 9…”

Section: Cross-linkingmentioning

confidence: 99%

Synthesis of Bipyridyl-Branched Polyoxazoline and Its Gelation by Means of Metal Coordination

Chujo

Sada

Sàegusa

1993

Polym J

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“…Polyelectrolyte hydrogels exhibit unique stimuli responsive physical properties, [1][2][3][4][5][6][7] and which have been widely utilized for many engineering applications including actuators, drug delivery and sensors. [8][9][10][11][12][13] Because the degree of charge dissociation in polyelectrolytes is dependent on the types of ion-pairs, the physical properties of polyelectrolyte hydrogels such as conductivity, elasticity and swelling ratio are affected by counterions as well as external stimuli.…”

Section: Doi: 101002/adma201103767mentioning

confidence: 99%

Photoresponsive Block Copolymer Photonic Gels with Widely Tunable Photosensitivity by Counter‐Ions

Ahn¹,

Kim²,

Hyon³

et al. 2012

Advanced Materials

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“…Indeed, the poly(N-isopropylacrylamide-co-methacrylic acid) (PNIPA-MAA) microgel particles [22] at pH 3.4 exhibited a decrease in Tc from 33.5 to 28 C with an increase in MAA content, whereas at pH 7.5, the higher MAA content resulted in the higher Tc. In weakly charged PNIPA hydrogels, addition of ionizable groups on the polymer network pronounced the volume changes when temperature crossed Tc [21,23,24]. The experimental studies [25] revealed that even distribution of ionic groups in the network affects the temperature of volume change transition.…”

Section: Effectors Of Volume Change In Hydrogelsmentioning

confidence: 99%

Hydrogel Films on Optical Fiber Core: Properties, Challenges, and Prospects for Future Applications

Казаков¹

2012

New Polymers for Special Applications

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There are experimental evidences [29][30][31] of de-swelling effects of different monovalent (Li + , Na + , K + , Cs + ) and divalent (Ca 2+ , Mg 2+ , Sr 2+ , Ba 2 ) ions in hydrogels of different chemical nature, including the biologically relevant gels [32] and cross-linked DNA [33]. Interestingly, at the same molar ratios of divalent to monovalent cations, ~ 1 mM to 30 mM, respectively, similar volume changes were observed in biological polyelectrolyte systems during physiological processes like nerve excitation, musle contraction, and cell locomotion [34][35][36][37][38][39][40].Surfactants. The extensive theoretical [41][42][43] and experimental [44][45][46][47][48] studies have shown that addition of anionic, cationic, and nonionic surfactants to the solution containing a gel can also influence the volume phase transition temperature and swelling degree of hydrogels depending on their hydrophobicity and charge of the polymer network. In general, addition of anionic or cationic surfactant to the solution of nonionic hydrogel rises the transition temperature as well as the swelling range, whereas the nonionic surfactant does not affect the transition temperature or the volume change. The surfactants with ionic head groups convert the neutral hydrogels to a polyelectrolyte gels when bind to the nonionic polymer networks, so that the transition temperatures elevate due to introduction of additional osmotic pressure by ionization. The changes in the volume phase transition are also dependent on the length of hydrophobic tail of ionic surfactants and the critical concentration of micelle formation. Indeed, it was found [45] that the transition temperature of nonionic poly(acryloyl-L-proline methyl ester) hydrogels increases more drastically in solutions of anionic sodium alkane sulfonate surfactants with the higher number of methylene units in the tail and at lower concentration than those with the shorter tails. The other interesting findings are [47]: (i) the amount of an ionic surfactant bound onto the swollen network of the nonionic PNIPA hydrogel is much greater than that to the collapsed

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Phase transition of submicron gel beads

Cited by 166 publications

References 5 publications

Synthesis of Bipyridyl-Branched Polyoxazoline and Its Gelation by Means of Metal Coordination

Synthesis of Bipyridyl-Branched Polyoxazoline and Its Gelation by Means of Metal Coordination

Photoresponsive Block Copolymer Photonic Gels with Widely Tunable Photosensitivity by Counter‐Ions

Hydrogel Films on Optical Fiber Core: Properties, Challenges, and Prospects for Future Applications

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