Studies on Structure of Cuprammonium Cellulose I. A Circular Dichroism Study on the Dissolved State of Cellulose in Cuprammonium Solution

Miyamoto, Ikuya; Inamoto, Miki; Matsui, Takayoshi; Saito, Masatoshi; Okajima, Kunihiko

doi:10.1295/polymj.27.1113

Cited by 32 publications

(22 citation statements)

References 13 publications

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“…Today, commercial production is either carried out via the viscose (Huber et al 2011;Klemm et al 2004) or the Lyocell processes (Rosenau et al 2002), using derivatizing and non-derivatizing solvents, respectively; these processes involve toxic derivatization steps or toxic and expensive chemicals. There are other known routes for cellulose dissolution with inorganic complexes (Miyamoto et al 1995;Saalwächter et al 2000), or certain exotic organic solvents (Philipp 1993), which, however, cannot be considered sustainable for large scale production. In the early 1990s, alkali-based aqueous solvents started to gain more academic and technical attention for the reasons of being more environmental benign than other protocols (Isogai and Atalla 1998;Kamide et al 1992;Zhou and Zhang 2000).…”

Section: Introductionmentioning

confidence: 99%

Spherical nanocomposite particles prepared from mixed cellulose–chitosan solutions

et al. 2016

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Novel cellulose-chitosan nanocomposite particles with spherical shape were successfully prepared via mixing of aqueous biopolymer solutions in three different ways. Macroparticles with diameters in the millimeter range were produced by dripping cellulose dissolved in cold LiOH/urea into acidic chitosan solutions, inducing instant co-regeneration of the biopolymers. Two types of microspheres, chemically crosslinked and non-crosslinked, were prepared by first mixing cellulose and chitosan solutions obtained from freeze thawing in LiOH/KOH/urea. Thereafter epichlorohydrin was applied as crosslinking agent for one of the samples, followed by water-inoil (W/O) emulsification, heat induced sol-gel transition, solvent exchange, washing and freeze-drying. Characterization by X-ray photoelectron spectroscopy, total elemental analysis, and Fourier transform infrared spectroscopy confirmed the prepared particles as being true cellulose-chitosan nanocomposites with different distribution of chitosan from the surface to the core of the particles depending on the preparation method. Field emission scanning electron microscopy and laser diffraction was performed to study the morphology and size distribution of the prepared particles. The morphology was found to vary due to different preparation routes, revealing a core shell structure for macroparticles prepared by dripping, and homogenous nanoporous structure for the microspheres. The non-crosslinked microparticles exhibited a somewhat denser structure than the crosslinked ones, which indicated that crosslinking restricts packing of the chains before and under regeneration. From the obtained volume-weighted size distributions it was found that the crosslinked microspheres had the highest median diameter. The results demonstrate that not only the mixing ratio and distribution of the two biopolymers, but also the morphology and nanocomposite particle diameters are tunable by choosing between the different routes of preparation.

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Section: Introductionmentioning

confidence: 99%

Spherical nanocomposite particles prepared from mixed cellulose–chitosan solutions

et al. 2016

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“…Recently, authors have confirmed that cellulose exists as b chelate structure with coordination of cuprammonium ions to hydroxyl groups at c2 and c3 positions of glucopyranose unit in cuprammonium hydroxide solution. 7 In addition, authors also revealed that the similar cellulosejcuprammonium hydroxide complex as that in solution could exist even in a solid state. 8 This means that the change in the chelate or complex structure of cellulose during coagulation process must be considered to discuss the morphological formation of the membrane besides simple phase equilibrium study.…”

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Morphological Formation of the Regenerated Cellulose Membranes Recovered from Its Cuprammonium Solution Using Various Coagulants

Inamoto

Miyamoto

Hongo

et al. 1996

Polym J

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ABSTRACT:Morphological formation of the regenerated cellulose membranes from its cuprammonium hydroxide solution was investigated in connection with the change in the complex form between cellulose and cuprammonium hydroxide and material transportation during coagulation process using various aqueous coagulants (H +, Na +, K +, NH4 +, Ca 2 +, Mg 2 + with various counter ions). Scanning electron microscopically observation revealed that the morphological distribution estimated by pore size distribution in the thickness direction of the membranes are categorized into four types (two gradient types, homogeneously dense type and skin/void type) depending on pH and cation species (not anion species) of the coagulants, which are in turn the determinant of water permeability of the membrane. The each type of morphology was proved well correlated to the change in circular dichroism (CD) spectra taken for the coagulated gels as a function of coagulation time, which was also correlated to the transportation of ammonia and cupric ion from the original cellulose solution into the coagulants. Thus, the controlling of the morphology of the membranes from cellulose/cuprammonium hydroxide solution could be possible by simply selecting the cationic species of coagulants in general and the membrane with gradient pore distribution and having a relatively higher water permeability is obtainable by acid or ammonium salts as coagulant.

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“…11 • 12 Some voids are seen especially for D series membranes. In any cases, the surface of D series membranes except for DCe 9 Ca 1 have far smaller pore than those for W series. The net work structure in which polymer particles are mutually connected to form pores are obvious especially for the surface of W series membranes.…”

Section: Resultsmentioning

confidence: 78%

“…Cotton linter supplied by Peterdemings Co., Ltd., was dissolved in aq cuprammonium hydroxide solution according to the known procedure 9 at cellulose concentration of 8 wt%. The molar composition of the solution (cellulosejCujNH 3 ) was adjusted constant as 0.05/ 0.046/0.36.…”

Section: Cellulose Solution Casein Solution and Their Mixturesmentioning

confidence: 99%

“…In another line of studies Okajima and his coworkers have already studied on the dissolved state (C 2 , C 3 -coordinate 15 chelate form) of cellulose in cuprammonium hydroxide, 9 the morphology of the regenerated cellulose membranes recovered from its cuprammonium hydroxide solution in relation to the changes in circular dichroism (CD) spectra of the cellulose solution during its coagulation process, 10 and the dimensional stability and morphology of the membranes obtained by changing coagulants in view of amorphous parameters. 11 • 12 Of the coagulants used, aq sulfuric acid was proved to decompose promptly the original cellulose jcuprammonium hydroxide complex, giving very porous structure, and in contrast, aq sodium hydroxide gives a gel with definite complex form, leading to very dense structure.…”

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Morphology and Amorphous Structure of Blend Membranes from Cellulose and Casein Recovered from Its Cuprammonium Solution

Yang

Yamane

Matsui

et al. 1997

Polym J

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ABSTRACT:Morphology, structure, and some properties of the blend membranes of cellulose/casein prepared from their cuprammonium hydroxide solution by alkali coagulation and subsequent acid neutralization were investigated in connection with the complex forms of cellulose in the mixed solutions and the change in complex forms developed by alkali coagulation. For this purpose, the cast solution was coagulated by either directly immersing the coagulation bath (W series) or after vaporization of ammonia in advance (D series). Circular dichroism (CD) measurements on the mixed solution and gel membranes revealed that the mixed solution with the fraction of casein fm 0.3 forms the independent caseinjcuprammonium hydroxide complex, hence giving phase-separated state in an optical anisotropic sense, and this upper limit shifts towards lower fm ( =0.2) during coagulation. Longest wavelength A for the charge transfer excitation of cellulose/cuprammonium complex was seen for the gel membrane with J;., = 0.1, where highest tensile strength and crystalline orientation for the membranes are realized. Mechanical relaxation analysis suggests that the amorphous structural formation for D and W series membranes are quite different and that for the former is on the whole determined by the existing state of casein and cellulose in the mixed solution not by that in the gel membranes. Except for porosity Pra the swelling anisotropy parameter L, was not correlated with (110) plane orientation parameter and most amorphous parameters, which control L, of the regenerated cellulose membranes.KEY WORDS Blend Membrane / Cellulose / Casein / Circular Dichroism Spectra / Mechanical Relaxation / Tensile Strength / Swelling Anisotropy / Many cellulose blends such as cellulosejpolyacrylonitrile/ cellulose/poly (vinyl alcohol), 2 cellulosejpoly(scaprolactone ), 3 and cellulose/poly( 4-vinylpyridine ) 4 using cellulose solvents recently discovered, such as N,Ndimethylacetamide-lithium chloride 1 -3 and dimethyl sulfoxide-paraformaldehyde 4 have been reported especially discussing "miscibility" of the blends. On the one hand, the cellulose/aqueous (aq) cuprammonium hydroxide solution, discovered by Schweitzer, 5 still has industrial importance for regenerated cellulose fiber formation in the textile field and the membrane formation in material separation field. Aqueous cuprammonium hydroxide acts some suitable solvent for many kinds of polymers such as polysaccharides, polyglucans, cellulose derivatives, natural proteins (silk fibroin, casein), water soluble synthetic polymers, and so on. This gives a fundamental basis for polymer blends using the cellulose/aq cuprammonium hydroxide system. In fact, we have studied using the above cuprammonium hydroxide solution system the cellulose blend membranes containing casein, 6 poly( vinyl alcohol), 7 gelatin, 8 and polyethylene glycohol 8 on their mechanical properties, permeability properties, and miscibility using scanning electron microscopy SEM, X-ray diffraction, 13 C NMR, and DSC analyses. For the cel...

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Studies on Structure of Cuprammonium Cellulose I. A Circular Dichroism Study on the Dissolved State of Cellulose in Cuprammonium Solution

Cited by 32 publications

References 13 publications

Spherical nanocomposite particles prepared from mixed cellulose–chitosan solutions

Spherical nanocomposite particles prepared from mixed cellulose–chitosan solutions

Morphological Formation of the Regenerated Cellulose Membranes Recovered from Its Cuprammonium Solution Using Various Coagulants

Morphology and Amorphous Structure of Blend Membranes from Cellulose and Casein Recovered from Its Cuprammonium Solution

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