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Toshiyuki Takano - One of the best experts on this subject based on the ideXlab platform.

  • Preparation of phthalocyanine-bound myristoyl Celluloses for photocurrent generation system
    Cellulose, 2017
    Co-Authors: Yasuko Saito, Hiroshi Kamitakahara, Toshiyuki Takano
    Abstract:

    The influences of two structural modifications on the photocurrent generation performance of the Langmuir–Blodgett (LB) film of the 6- O -phthalocyaninyl Cellulose Derivative were investigated. These structural modifications were the substituent groups at the O -2 and O -3 positions, and the central metal of the phthalocyanine moiety. Specifically, 6- O -Zn/phthalocyaninyl- ( 8a ) and Pd/phthalocyaninyl ( 8b ) -2,3-di- O -myristoylCelluloses were prepared instead of 6- O -Zn/phthalocyaninyl-2,3-di- O -myristylCellulose ( 2 ). The LB monolayer film of compound 8a on an indium thin oxide electrode showed higher photocurrent generation performance than that of compound 2 . This suggested that myristoyl groups (C-14 acyl groups) were more beneficial to photocurrent generation than myristyl groups (C-14 alkyl groups), as the substituent at the O -2 and O -3 positions. The LB monolayer film of compound 8b showed photocurrent generation from 500 to 700 nm, although a blue-shift in the Q-band maximum was observed. The photocurrent generation performance of compound 8b was significantly higher than that of compound 8a . This indicated that Pd was more beneficial to photocurrent generation than Zn. The film of compound 8b prepared by the horizontal lifting method showed better photocurrent generation performance than that prepared by the vertical dipping method. Consequently, compound 8b is a complementary material to the porphyrin-appended Cellulose Derivative ( 1 ) for photocurrent generation system.

  • Preparation of (ruthenium (II) complex)-bound Cellulose Derivative for photocurrent generation system
    Journal of Wood Science, 2016
    Co-Authors: Yasuko Saito, Hiroshi Kamitakahara, Toshiyuki Takano
    Abstract:

    6-O-[Acetylacetonato-bis(2,2′-bipyridine)ruthenium(II)]-2,3-di-O-myristyl Cellulose (3) was prepared from 2,3-di-O-myristyl Cellulose (1) by two reaction steps in 37.7 % total yield. The LB monolayer film of compound 3 was successfully deposited onto an indium tin oxide electrode by a vertical dipping method and showed photocurrent generation performance in the range of 400–600 nm. Compound 3 was expected as a complementary material of porphyrin-bound Cellulose Derivative for biomaterial-based solar cells.

  • Preparation of a squaraine-bounded Cellulose Derivative for photocurrent generation system.
    Carbohydrate Research, 2016
    Co-Authors: Yasuko Saito, Hiroshi Kamitakahara, Toshiyuki Takano
    Abstract:

    Abstract A regio-selectively squaraine (SQ)-bounded Cellulose Derivative ( 4 ) with a degree of substitution of SQ (DS SQ ) of 0.55 was prepared from 6- O -(4-methoxytrityl) Cellulose ( 1 ) by three reaction steps in 77% total yield. Lauryl SQ carboxylate ( 8 ) was also prepared as a reference sample. The photostability of SQ moieties of compound 4 in CHCl 3 was not improved when compared with SQ-COOH ( 7 ), but that of SQ moiety of compound 8 was improved unexpectedly. The Langmuir–Blodgett monolayer films 4B and 8B on an indium tin oxide (ITO) electrode were successfully prepared from compounds 4 and 8 by a vertical dipping method, respectively. The films 4B and 8B showed photocurrent generation performances in the region of 550–680 nm. The quantum yield at 650 nm of film 4B was higher than that of film 8B . These results showed that the Cellulose backbone of compound 4 acts as an effective scaffold for the good photocurrent generation performances and that compound 4 was a promising complementary material of the porphyrin-bounded Cellulose Derivatives (for photocurrent generation at 400–420 nm) for effective utilization of solar light, as well as the phthalocyanine-bounded Cellulose Derivatives (for photocurrent generation at 650–720 nm).

  • preparation of langmuir blodgett monolayer films of zinc ii phthalocyanine containing Cellulose Derivative the use of 2 3 di o myristyl Cellulose as a scaffold
    Cellulose, 2014
    Co-Authors: Yasuko Saito, Hiroshi Kamitakahara, Toshiyuki Takano
    Abstract:

    The 6-O-phthalocyanine Cellulose Derivative, 2,3-di-O-myristyl-6-O-[p-(9(10),16(17),23(24)-tri-tert-butyl-2-zinc(II)phthalocyaninyl-benzoyl)Cellulose (8e) was synthesized in a high yield with the degree of substitution of 0.33 for the phthalocyaninyl group (DSphthalocyanine) via the esterification of 2,3-di-O-myristyl Cellulose (1) with the mono-substituted phthalocyanine Derivative ([9(10),16(17),23(24)-tri-tert-butyl-2-[4-(carboxy)phenoxy]phthalocyaninato]zinc(II), 7). A chloroform solution of compound 8e was more stable under illumination than that of low molecular weight phthalocyanine, [2(3),9(10),16(17),23(24)-tetrakis(tert-butyl)phthalocyaninato]zinc(II). Langmuir–Blodgett (LB) monolayer films of compound 8e were prepared on a variety of different substrates using the vertical dipping method with an annealing time of 5 min. An LB monolayer film of compound 8e on an indium tin oxide (ITO) electrode exhibited a photocurrent generation performance in the range of 600–700 nm. The photocurrent density of the film composed of 8e at 680 nm was better than that of 2,3-di-O-myristyl-6-O-(zinc(II) phthalocyaninyl) Cellulose (3) which was the corresponding phthalocyanine-containing Cellulose synthesized through a phthalocyanine-ring forming reaction on the Cellulose backbone according to an existing procedure.

  • synthesis of zinc ii phthalocyanine containing Cellulose Derivative using phthalocyanine ring formation reaction
    Cellulose, 2012
    Co-Authors: Yasuko Saito, Toshiyuki Takano, Hiroshi Kamitakahara, Keita Sakakibara, Fumiaki Nakatsubo
    Abstract:

    2,3-Di-O-myristyl-6-O-(zinc(II) phthalocyaninyl) Cellulose (5) was synthesized from Cellulose (1) by five reaction steps via 6-O-(3′,4′-dicyanophenyl)-2,3-di-O-myristyl Cellulose (4). The key reaction was phthalocyanine-ring formation on a Cellulose backbone, that is, the reaction of compound 4 with o-phthalodinitrile in the presence of hexamethyldisilazane and zinc acetate in DMF afforded to compound 5 in 35.4 % yield. Consequently, the degree of substitution with phthalocyanine moieties of compound 5 was 0.38. The LB monolayer film of compound 5 on an indium tin oxide (ITO) electrode was found to show photocurrent generation performance at 680 nm.

Fumiaki Nakatsubo - One of the best experts on this subject based on the ideXlab platform.

  • synthesis of zinc ii phthalocyanine containing Cellulose Derivative using phthalocyanine ring formation reaction
    Cellulose, 2012
    Co-Authors: Yasuko Saito, Toshiyuki Takano, Hiroshi Kamitakahara, Keita Sakakibara, Fumiaki Nakatsubo
    Abstract:

    2,3-Di-O-myristyl-6-O-(zinc(II) phthalocyaninyl) Cellulose (5) was synthesized from Cellulose (1) by five reaction steps via 6-O-(3′,4′-dicyanophenyl)-2,3-di-O-myristyl Cellulose (4). The key reaction was phthalocyanine-ring formation on a Cellulose backbone, that is, the reaction of compound 4 with o-phthalodinitrile in the presence of hexamethyldisilazane and zinc acetate in DMF afforded to compound 5 in 35.4 % yield. Consequently, the degree of substitution with phthalocyanine moieties of compound 5 was 0.38. The LB monolayer film of compound 5 on an indium tin oxide (ITO) electrode was found to show photocurrent generation performance at 680 nm.

  • Syntheses of 2,6-O-alkyl Celluloses: influence of methyl and ethyl groups regioselectively introduced at O-2 and O-6 positions on their solubility
    Cellulose, 2009
    Co-Authors: Hiroshi Kamitakahara, Toshiyuki Takano, Toshihiro Funakoshi, Fumiaki Nakatsubo
    Abstract:

    2,6-Di-O-ethyl (2E6E) (1), 2-O-ethyl-6-O-methyl (2E6M) (2), and 6-O-ethyl-2-O-methyl (6E2M) (3) Celluloses were synthesized via ring-opening polymerization of glucose orthopivalate Derivatives. 2,6-Di-O-methyl Cellulose (2M6M) was insoluble in any common solvents, though it was not expected. On the other hand, Cellulose Derivative 1 (2E6E) was soluble in chloroform. Introduced positions of alkyl groups on Cellulose affected solubilities of Cellulose Derivatives. Their solubility in chloroform decreased in the order: polymer 1 (2E6E) > polymer 2 (2E6M) > polymer 3 (6E2M) ≫ 2M6M.

  • Syntheses and comparison of 2,6-di-O-methyl Celluloses from natural and synthetic Celluloses.
    Macromolecular Bioscience, 2008
    Co-Authors: Hiroshi Kamitakahara, Fumiaki Nakatsubo, Thomas Heinze, Andreas Koschella, Yuji Mikawa, Dieter Klemm
    Abstract:

    2,6-Di-O-methylCellulose was prepared from natural and synthetic Celluloses. Natural Cellulose was converted to 2,6-di-O-thexyldimethylsilylCellulose, then to 3-mono-O-allyl-2,6-di-O-methylCellulose, and finally into 2,6-di-O-methylCellulose. Alternatively, 2,6 di-O-methyl-Cellulose was synthesized trom the synthetic Cellulose Derivative 3-mono-O-benzyl-2,6-di-O-pivaloylCellulose by depivaloylation and methylation to give 3-mono-O-benzyl-2,6-di-O-methyl-Cellulose, which was debenzylated to yield the dimethyl ether. Both types of 2,6-di-O-methyl-Cellulose are insoluble in water and common organic solvents. The structures of all Cellulose Derivatives were determined by NMR.

  • Preparation of high regioselectively mono-substituted carboxymethylCelluloses
    Cellulose Chemistry and Technology, 2005
    Co-Authors: Naotaka Nishio, Toshiyuki Takano, Hiroshu Kamitakahara, Fumiaki Nakatsubo
    Abstract:

    High regioselectively mono-substituted carboxymethylCelluloses (that is, 6-0-CarboxymethylCellulose (6-O-CMC), 3-O-CarboxymethylCellulose (3-O-CMC), 2-0-CarboxymethylCellulose (2-O-CMC)) were prepared by ring-opening polymerization of glucose orthoester Derivatives. In the synthesis of 6-O-CMC or 3-O-CMC, tert-butyloxycarbonylmethyl (t-BCM) group, which can be converted to carboxymethyl group, was introduced to the orthoester at 0-3 or 0-6 position, respectively, before polymerization. On the other hand, 2-O-CMC was prepared by tert-butyloxy-carbonylmethylation of the Cellulose Derivative, which had a free hydroxyl group at C-2 position, after polymerization.

Hiroshi Kamitakahara - One of the best experts on this subject based on the ideXlab platform.

  • Preparation of phthalocyanine-bound myristoyl Celluloses for photocurrent generation system
    Cellulose, 2017
    Co-Authors: Yasuko Saito, Hiroshi Kamitakahara, Toshiyuki Takano
    Abstract:

    The influences of two structural modifications on the photocurrent generation performance of the Langmuir–Blodgett (LB) film of the 6- O -phthalocyaninyl Cellulose Derivative were investigated. These structural modifications were the substituent groups at the O -2 and O -3 positions, and the central metal of the phthalocyanine moiety. Specifically, 6- O -Zn/phthalocyaninyl- ( 8a ) and Pd/phthalocyaninyl ( 8b ) -2,3-di- O -myristoylCelluloses were prepared instead of 6- O -Zn/phthalocyaninyl-2,3-di- O -myristylCellulose ( 2 ). The LB monolayer film of compound 8a on an indium thin oxide electrode showed higher photocurrent generation performance than that of compound 2 . This suggested that myristoyl groups (C-14 acyl groups) were more beneficial to photocurrent generation than myristyl groups (C-14 alkyl groups), as the substituent at the O -2 and O -3 positions. The LB monolayer film of compound 8b showed photocurrent generation from 500 to 700 nm, although a blue-shift in the Q-band maximum was observed. The photocurrent generation performance of compound 8b was significantly higher than that of compound 8a . This indicated that Pd was more beneficial to photocurrent generation than Zn. The film of compound 8b prepared by the horizontal lifting method showed better photocurrent generation performance than that prepared by the vertical dipping method. Consequently, compound 8b is a complementary material to the porphyrin-appended Cellulose Derivative ( 1 ) for photocurrent generation system.

  • Preparation of (ruthenium (II) complex)-bound Cellulose Derivative for photocurrent generation system
    Journal of Wood Science, 2016
    Co-Authors: Yasuko Saito, Hiroshi Kamitakahara, Toshiyuki Takano
    Abstract:

    6-O-[Acetylacetonato-bis(2,2′-bipyridine)ruthenium(II)]-2,3-di-O-myristyl Cellulose (3) was prepared from 2,3-di-O-myristyl Cellulose (1) by two reaction steps in 37.7 % total yield. The LB monolayer film of compound 3 was successfully deposited onto an indium tin oxide electrode by a vertical dipping method and showed photocurrent generation performance in the range of 400–600 nm. Compound 3 was expected as a complementary material of porphyrin-bound Cellulose Derivative for biomaterial-based solar cells.

  • Preparation of a squaraine-bounded Cellulose Derivative for photocurrent generation system.
    Carbohydrate Research, 2016
    Co-Authors: Yasuko Saito, Hiroshi Kamitakahara, Toshiyuki Takano
    Abstract:

    Abstract A regio-selectively squaraine (SQ)-bounded Cellulose Derivative ( 4 ) with a degree of substitution of SQ (DS SQ ) of 0.55 was prepared from 6- O -(4-methoxytrityl) Cellulose ( 1 ) by three reaction steps in 77% total yield. Lauryl SQ carboxylate ( 8 ) was also prepared as a reference sample. The photostability of SQ moieties of compound 4 in CHCl 3 was not improved when compared with SQ-COOH ( 7 ), but that of SQ moiety of compound 8 was improved unexpectedly. The Langmuir–Blodgett monolayer films 4B and 8B on an indium tin oxide (ITO) electrode were successfully prepared from compounds 4 and 8 by a vertical dipping method, respectively. The films 4B and 8B showed photocurrent generation performances in the region of 550–680 nm. The quantum yield at 650 nm of film 4B was higher than that of film 8B . These results showed that the Cellulose backbone of compound 4 acts as an effective scaffold for the good photocurrent generation performances and that compound 4 was a promising complementary material of the porphyrin-bounded Cellulose Derivatives (for photocurrent generation at 400–420 nm) for effective utilization of solar light, as well as the phthalocyanine-bounded Cellulose Derivatives (for photocurrent generation at 650–720 nm).

  • preparation of langmuir blodgett monolayer films of zinc ii phthalocyanine containing Cellulose Derivative the use of 2 3 di o myristyl Cellulose as a scaffold
    Cellulose, 2014
    Co-Authors: Yasuko Saito, Hiroshi Kamitakahara, Toshiyuki Takano
    Abstract:

    The 6-O-phthalocyanine Cellulose Derivative, 2,3-di-O-myristyl-6-O-[p-(9(10),16(17),23(24)-tri-tert-butyl-2-zinc(II)phthalocyaninyl-benzoyl)Cellulose (8e) was synthesized in a high yield with the degree of substitution of 0.33 for the phthalocyaninyl group (DSphthalocyanine) via the esterification of 2,3-di-O-myristyl Cellulose (1) with the mono-substituted phthalocyanine Derivative ([9(10),16(17),23(24)-tri-tert-butyl-2-[4-(carboxy)phenoxy]phthalocyaninato]zinc(II), 7). A chloroform solution of compound 8e was more stable under illumination than that of low molecular weight phthalocyanine, [2(3),9(10),16(17),23(24)-tetrakis(tert-butyl)phthalocyaninato]zinc(II). Langmuir–Blodgett (LB) monolayer films of compound 8e were prepared on a variety of different substrates using the vertical dipping method with an annealing time of 5 min. An LB monolayer film of compound 8e on an indium tin oxide (ITO) electrode exhibited a photocurrent generation performance in the range of 600–700 nm. The photocurrent density of the film composed of 8e at 680 nm was better than that of 2,3-di-O-myristyl-6-O-(zinc(II) phthalocyaninyl) Cellulose (3) which was the corresponding phthalocyanine-containing Cellulose synthesized through a phthalocyanine-ring forming reaction on the Cellulose backbone according to an existing procedure.

  • synthesis of zinc ii phthalocyanine containing Cellulose Derivative using phthalocyanine ring formation reaction
    Cellulose, 2012
    Co-Authors: Yasuko Saito, Toshiyuki Takano, Hiroshi Kamitakahara, Keita Sakakibara, Fumiaki Nakatsubo
    Abstract:

    2,3-Di-O-myristyl-6-O-(zinc(II) phthalocyaninyl) Cellulose (5) was synthesized from Cellulose (1) by five reaction steps via 6-O-(3′,4′-dicyanophenyl)-2,3-di-O-myristyl Cellulose (4). The key reaction was phthalocyanine-ring formation on a Cellulose backbone, that is, the reaction of compound 4 with o-phthalodinitrile in the presence of hexamethyldisilazane and zinc acetate in DMF afforded to compound 5 in 35.4 % yield. Consequently, the degree of substitution with phthalocyanine moieties of compound 5 was 0.38. The LB monolayer film of compound 5 on an indium tin oxide (ITO) electrode was found to show photocurrent generation performance at 680 nm.

Yasuko Saito - One of the best experts on this subject based on the ideXlab platform.

  • Preparation of phthalocyanine-bound myristoyl Celluloses for photocurrent generation system
    Cellulose, 2017
    Co-Authors: Yasuko Saito, Hiroshi Kamitakahara, Toshiyuki Takano
    Abstract:

    The influences of two structural modifications on the photocurrent generation performance of the Langmuir–Blodgett (LB) film of the 6- O -phthalocyaninyl Cellulose Derivative were investigated. These structural modifications were the substituent groups at the O -2 and O -3 positions, and the central metal of the phthalocyanine moiety. Specifically, 6- O -Zn/phthalocyaninyl- ( 8a ) and Pd/phthalocyaninyl ( 8b ) -2,3-di- O -myristoylCelluloses were prepared instead of 6- O -Zn/phthalocyaninyl-2,3-di- O -myristylCellulose ( 2 ). The LB monolayer film of compound 8a on an indium thin oxide electrode showed higher photocurrent generation performance than that of compound 2 . This suggested that myristoyl groups (C-14 acyl groups) were more beneficial to photocurrent generation than myristyl groups (C-14 alkyl groups), as the substituent at the O -2 and O -3 positions. The LB monolayer film of compound 8b showed photocurrent generation from 500 to 700 nm, although a blue-shift in the Q-band maximum was observed. The photocurrent generation performance of compound 8b was significantly higher than that of compound 8a . This indicated that Pd was more beneficial to photocurrent generation than Zn. The film of compound 8b prepared by the horizontal lifting method showed better photocurrent generation performance than that prepared by the vertical dipping method. Consequently, compound 8b is a complementary material to the porphyrin-appended Cellulose Derivative ( 1 ) for photocurrent generation system.

  • Preparation of (ruthenium (II) complex)-bound Cellulose Derivative for photocurrent generation system
    Journal of Wood Science, 2016
    Co-Authors: Yasuko Saito, Hiroshi Kamitakahara, Toshiyuki Takano
    Abstract:

    6-O-[Acetylacetonato-bis(2,2′-bipyridine)ruthenium(II)]-2,3-di-O-myristyl Cellulose (3) was prepared from 2,3-di-O-myristyl Cellulose (1) by two reaction steps in 37.7 % total yield. The LB monolayer film of compound 3 was successfully deposited onto an indium tin oxide electrode by a vertical dipping method and showed photocurrent generation performance in the range of 400–600 nm. Compound 3 was expected as a complementary material of porphyrin-bound Cellulose Derivative for biomaterial-based solar cells.

  • Preparation of a squaraine-bounded Cellulose Derivative for photocurrent generation system.
    Carbohydrate Research, 2016
    Co-Authors: Yasuko Saito, Hiroshi Kamitakahara, Toshiyuki Takano
    Abstract:

    Abstract A regio-selectively squaraine (SQ)-bounded Cellulose Derivative ( 4 ) with a degree of substitution of SQ (DS SQ ) of 0.55 was prepared from 6- O -(4-methoxytrityl) Cellulose ( 1 ) by three reaction steps in 77% total yield. Lauryl SQ carboxylate ( 8 ) was also prepared as a reference sample. The photostability of SQ moieties of compound 4 in CHCl 3 was not improved when compared with SQ-COOH ( 7 ), but that of SQ moiety of compound 8 was improved unexpectedly. The Langmuir–Blodgett monolayer films 4B and 8B on an indium tin oxide (ITO) electrode were successfully prepared from compounds 4 and 8 by a vertical dipping method, respectively. The films 4B and 8B showed photocurrent generation performances in the region of 550–680 nm. The quantum yield at 650 nm of film 4B was higher than that of film 8B . These results showed that the Cellulose backbone of compound 4 acts as an effective scaffold for the good photocurrent generation performances and that compound 4 was a promising complementary material of the porphyrin-bounded Cellulose Derivatives (for photocurrent generation at 400–420 nm) for effective utilization of solar light, as well as the phthalocyanine-bounded Cellulose Derivatives (for photocurrent generation at 650–720 nm).

  • preparation of langmuir blodgett monolayer films of zinc ii phthalocyanine containing Cellulose Derivative the use of 2 3 di o myristyl Cellulose as a scaffold
    Cellulose, 2014
    Co-Authors: Yasuko Saito, Hiroshi Kamitakahara, Toshiyuki Takano
    Abstract:

    The 6-O-phthalocyanine Cellulose Derivative, 2,3-di-O-myristyl-6-O-[p-(9(10),16(17),23(24)-tri-tert-butyl-2-zinc(II)phthalocyaninyl-benzoyl)Cellulose (8e) was synthesized in a high yield with the degree of substitution of 0.33 for the phthalocyaninyl group (DSphthalocyanine) via the esterification of 2,3-di-O-myristyl Cellulose (1) with the mono-substituted phthalocyanine Derivative ([9(10),16(17),23(24)-tri-tert-butyl-2-[4-(carboxy)phenoxy]phthalocyaninato]zinc(II), 7). A chloroform solution of compound 8e was more stable under illumination than that of low molecular weight phthalocyanine, [2(3),9(10),16(17),23(24)-tetrakis(tert-butyl)phthalocyaninato]zinc(II). Langmuir–Blodgett (LB) monolayer films of compound 8e were prepared on a variety of different substrates using the vertical dipping method with an annealing time of 5 min. An LB monolayer film of compound 8e on an indium tin oxide (ITO) electrode exhibited a photocurrent generation performance in the range of 600–700 nm. The photocurrent density of the film composed of 8e at 680 nm was better than that of 2,3-di-O-myristyl-6-O-(zinc(II) phthalocyaninyl) Cellulose (3) which was the corresponding phthalocyanine-containing Cellulose synthesized through a phthalocyanine-ring forming reaction on the Cellulose backbone according to an existing procedure.

  • synthesis of zinc ii phthalocyanine containing Cellulose Derivative using phthalocyanine ring formation reaction
    Cellulose, 2012
    Co-Authors: Yasuko Saito, Toshiyuki Takano, Hiroshi Kamitakahara, Keita Sakakibara, Fumiaki Nakatsubo
    Abstract:

    2,3-Di-O-myristyl-6-O-(zinc(II) phthalocyaninyl) Cellulose (5) was synthesized from Cellulose (1) by five reaction steps via 6-O-(3′,4′-dicyanophenyl)-2,3-di-O-myristyl Cellulose (4). The key reaction was phthalocyanine-ring formation on a Cellulose backbone, that is, the reaction of compound 4 with o-phthalodinitrile in the presence of hexamethyldisilazane and zinc acetate in DMF afforded to compound 5 in 35.4 % yield. Consequently, the degree of substitution with phthalocyanine moieties of compound 5 was 0.38. The LB monolayer film of compound 5 on an indium tin oxide (ITO) electrode was found to show photocurrent generation performance at 680 nm.

Laszlo Wojnarovits - One of the best experts on this subject based on the ideXlab platform.

  • Synthesis of carboxymethylCellulose/starch superabsorbent hydrogels by gamma-irradiation
    Chemistry Central Journal, 2017
    Co-Authors: Tamas Fekete, Judit Borsa, Erzsebet Takacs, Laszlo Wojnarovits
    Abstract:

    Superabsorbent hydrogels show a large potential in a wide array of applications due to their unique properties. CarboxymethylCellulose (CMC) is a commercially available water-soluble Cellulose Derivative of major interest in the hydrogel synthesis. High-energy irradiation allows the chemical crosslinking without the use of crosslinking agents, while the introduction of other natural or synthetic polymers offers a convenient way to modify the gels. In this study we examined the effect of the addition of starch, a low-cost renewable polysaccharide, on the properties of carboxymethylCellulose-based hydrogels. Superabsorbent gels were prepared by gamma irradiation from aqueous mixtures of carboxymethylCellulose and starch. The partial replacement of CMC with starch improved the gel fraction, while a slight increase in the water uptake was also observed. However, very high starch content had a negative impact on the gelation, resulting in a decrease in gel fraction. Moreover, higher solute concentrations were preferred for the gelation of CMC/starch than for pure CMC. Hydrogels containing 30% starch showed the best properties: a water uptake of ~350 gwater/ggel was achieved with ~55% gel fraction synthesized from 15 w/w% solutions at 20 kGy. Heterogeneous gel structure was observed: the starch granules and fragments were dispersed in the CMC matrix. The swelling of CMC/starch gels showed a high sensitivity to the ionic strength in water due to the CMC component. However, the mixed gels are less sensitive to the ionic strength than pure CMC gels. The introduction of starch to carboxymethylCellulose systems led to improved properties. Such gels showed higher water uptake, especially in an environment with high electrolyte concentration. CMC/starch hydrogels may offer a cheaper, superior alternative compared to pure Cellulose Derivative-based gels depending on the application.

  • synthesis of Cellulose Derivative based superabsorbent hydrogels by radiation induced crosslinking
    Cellulose, 2014
    Co-Authors: Tamas Fekete, Judit Borsa, Erzsebet Takacs, Laszlo Wojnarovits
    Abstract:

    Hydrogels with high water uptake were prepared by ionizing radiation induced crosslinking in aqueous solutions of four Cellulose Derivatives (carboxymethylCellulose sodium salt—CMC-Na, methylCellulose—MC, hydroxyethylCellulose—HEC and hydroxypropylCellulose—HPC). The gel fraction increased with absorbed dose, while water uptake decreased. At high polymer concentrations lower gel fractions were found due to the lower polymer chain mobility and inhomogeneity at low water content. The swelling rate gradually slowed down after 4–5 h. CMC and HEC gels reached equilibrium after 24 h, while HPC and MC gels required longer immersion times. Gels showed second-order swelling kinetics in water. The mechanism of the water diffusion proved to be anomalous. In pure water, CMC gels showed the highest, while HPC and MC gels the lowest water uptake. The Derivatives had different sensitivities to ionic strength in the swelling solution. The salt type also proved to be a significant factor at uniform ionic strength. Thus different Cellulose Derivative based gels may be preferred at various applications depending on the environment.