Synthesis and Swelling/De-swelling Behavior of Core-Shell Type Gel Consisting of Two Different Poly(N-alkylacrylamide) Gel Layers

Iizawa, Takashi; Terao, Akihiro; Ohuchida, Machiko; Matsuura, Yoshinobu; Onohara, Yukio

doi:10.1295/polymj.pj2007044

Cited by 4 publications

(7 citation statements)

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“…The amidated parts showed strong absorption peaks at 3300 cm À1 (N-H, stretching), 1650 and 1545 cm À1 (amide I and amide II) with no absorption occurring at 1755 cm À1 (C=O of phenyl ester). The shell layer and core of the core-shell type gel beads showed absorption peaks characteristic of PNIPA at 1385, 1368, 1173 and 1131 cm À1 and of PNNPA at 1384 and 1153 cm À1 ; the absorption spectra were clearly consistent with those of PNIPA and PNNPA gels prepared by radical polymerization, 8 as well as the corresponding cylindrical gels, 11 respectively. The spectra appear to have trace absorption at 1710 cm À1 (C=O of carboxylic acid).…”

Section: Characterization Of the Gel Beads Obtained By The Second Amimentioning

confidence: 62%

“…The same results were observed in the corresponding reaction of cylindrical DAA. 11 The complete amidation of G-2 and G-4 (r t =R 0 ¼ 0:70) gave the corresponding PNAA(2)-PNAA(1) core-shell type gel beads, G-7 and G-8, respectively (Table II).…”

Section: Resultsmentioning

confidence: 99%

“…11 The equilibrium-swelling ratio for PNIPA and PNNPA gel beads was measured in water over a wide temperature range ( Figure 5). The PNIPA and beads PNNPA showed the maximal equilibrium-swelling ratio at a temperature several degrees lower than their lower critical solution temperatures (LCSTs), where these beads hardly swelled at a temperature above the LCST.…”

Section: Thermal Swelling/de-swelling Behavior Of the Homopolymer Gelmentioning

confidence: 99%

“…11 Since the resulting core-shell type gel has essentially the same main chain structure and shape as the original DAA sample, it has a defined structure-a continuous network and a boundary between two layers. This core-shell type gel corresponds to well-controlled crosslinking block copolymers with double thermosensitivity.…”

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confidence: 99%

“…For example, the resulting asymmetric core-shell gels showed a marked deformation between bending and stretching in response to water temperature changes. 11,15 Unfortunately, the reaction and the swelling/de-swelling behavior of the cylindrical gels cannot be precisely observed, because the shapes become distorted during the reaction and the swelling/de-swelling. In a previous paper, 16 the authors reported the heterogeneous esterification of poly(2-hydroxyethyl acrylate) (PHEA) gel beads resulting from sedimentation polymerization with acetic anhydride to give fine spherical core-shell type beads containing an esterified shell and an unreacted core.…”

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Synthesis of Core-Shell Type Gel Beads Consisting of Two Different Poly(N-alkylacrylamide) Gel Layers, and Their Thermosensitive Behavior

et al. 2009

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Mm-size monodispersed poly(acrylic acid) gel-1,8-diazabicyclo [5,4,0]undec-7-ene (DBU) salt (DAA) beads were prepared via a two-step procedure involving the sedimentation copolymerization of acrylic acid with 0.5 mol % of MBAA and neutralization of the resulting gel with excess DBU in methanol. When the resulting DAA beads were placed in N-methyl-2-pyrrolidone containing an excess of alkylamine and triphenylphosphine, selective amidation occurred from the outside to give the corresponding DAA-poly(N-alkylacrylamide) (PNAA) core-shell type gel bead, consisting of an unreacted DAA core and an amidated shell layer. The thickness of the shell layer could be controlled by the reaction time. Second amidation of the obtained DAA-PNAA core-shell type gel bead with another alkylamine resulted in a novel mm-size monodispersed core-shell type bead consisting of two different PNAA layers, poly(N-n-propylacrylamide) and poly(N-isopropylacrylamide). The swelling and de-swelling of the gel bead shell layer and core occurred independently in response to temperature changes. The amidation of the DAA beads and the swelling/de-swelling of the amidated gel beads occurred isotropically, and they maintained their spherical shapes.KEY WORDS: Double Thermosensitive Gel / Sedimentation Polymerization / Poly(Nalkylacrylamide) Gel / Core-Shell Type Gel / Sedimentation polymerization has attracted attention as a synthetic method for the production of mm-size monodispersed beads.1 These beads can usually be obtained from a classification of the beads prepared by suspension polymerization. The yield is so low that pellet-type gels have often been used instead of these beads. However, sedimentation polymerization can effectively produce mm-size monodispersed beads. The polymerization mechanism has been described as follows: when an aqueous monomer solution is injected dropwise to an immiscible heat medium (liquid paraffin or silicone oil), surface gelation of droplets descending in the medium takes place to give a stable skin, which prevents coalescence at the base of the reactor, and the polymerization is completed at the base.Improved sedimentation polymerization systems such as oilin-water-in-oil sedimentation polymerization; 2 compressed fluid sedimentation polymerization using supercritical carbon dioxide as a heat medium; 3 nonaqueous sedimentation polymerization using an aprotic polar solvent; 4 application to the crosslinking reaction of poly(vinyl alcohol) with glutaraldehyde; 5 and, polycondensation of tetraethyl orthosilicate 6 have been investigated. Mm-size functional polymer beads such as composite polymer beads, 5 interpenetrating polymer network beads, 5 and porous polymer beads 2,7 have been prepared by these methods. However, the chemical modification of beads prepared by sedimentation polymerization has rarely been reported. In the sedimentation polymerization of an aqueous Nalkylacrylamide solution, phase-separation occurred to give porous hollow particles. 7,8 These results support the polymerization mechanism described a...

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Section: Characterization Of the Gel Beads Obtained By The Second Amimentioning

confidence: 62%

Section: Resultsmentioning

confidence: 99%

Section: Thermal Swelling/de-swelling Behavior Of the Homopolymer Gelmentioning

confidence: 99%

mentioning

confidence: 99%

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confidence: 99%

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