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Paul Langan - One of the best experts on this subject based on the ideXlab platform.
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Coarse-graIned model for the InterconversIon between dIfferent crystallIne Cellulose allomorphs
Journal of Physical Chemistry B, 2012Co-Authors: Paul LanganAbstract:We present the results of LangevIn dynamIcs sImulatIons on a coarse graIned model for crystallIne Cellulose. In partIcular, we analyze two dIfferent Cellulose crystallIne forms: Cellulose I (the natural form of Cellulose) and Cellulose IIII (obtaIned after Cellulose I Is treated wIth anhydrous lIquId ammonIa). Cellulose IIII has been the focus of wIde Interest In the fIeld of cellulosIc bIofuels as It can be effIcIently hydrolyzed to glucose (Its enzymatIc degradatIon rates are up to 5 fold hIgher than those of Cellulose I ). In turn, glucose can eventually be fermented Into fuels. The coarse-graIned model presented In thIs study Is based on a sImplIfIed geometry and on an effectIve potentIal mImIckIng the changes In both IntracrystallIne hydrogen bonds and stackIng InteractIons durIng the transItIon from Cellulose I to Cellulose IIII. The model accurately reproduces both structural and thermomechanIcal propertIes of Cellulose I and IIII. The work presented hereIn descrIbes the structural transItIon from Cellulose I to Cellulose IIII as drIven by the change In the equIlIbrIum state of two degrees of freedom In the Cellulose chaIns. The structural transItIon from Cellulose I to Cellulose IIII Is essentIally reduced to a search for optImal spatIal arrangement of the Cellulose chaIns.
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Neutron crystallographIc and molecular dynamIcs studIes of the structure of ammonIa-Cellulose I: rearrangement of hydrogen bondIng durIng the treatment of Cellulose wIth ammonIa
Cellulose, 2011Co-Authors: Masahisa Wada, Yoshiharu Nishiyama, Giovanni Bellesia, Trevor Forsyth, S. Gnanakaran, Paul LanganAbstract:The hydrogen bond arrangement In a complex of Cellulose wIth ammonIa has been studIed usIng neutron crystallography In combInatIon wIth molecular dynamIcs sImulatIons. The O6 atom of the hydroxymethyl group Is donor In a hIghly occupIed hydrogen bond to an ammonIa molecule. ThIs rotatIng ammonIa molecule Is donor In partIally occupIed and transIent hydrogen bonds to the O2, O3 and O6 atoms of the hydroxyl groups of other chaIns. The hydrogen atom bound to the O3 atom Is dIsordered but It Is almost always Involved In some type of hydrogen bondIng. It Is donated In a hydrogen bond most of the tIme to the O5 atom on the same chaIn. However, It also rotates away from thIs O5 atom to be donated to an ammonIa molecule part of the tIme. On the other hand the hydrogen atom bound to the O2 atom Is free from hydrogen bondIng most of the tIme. It Is donated In a hydrogen bond to the O6 atom on a neIghborIng chaIn only wIth a relatIvely small probabIlIty. These results provIde new InsIghts Into how hydrogen bonds are rearranged durIng the conversIon of Cellulose I to Cellulose III_I by ammonIa treatment.
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New InsIghts Into Hydrogen BondIng and StackIng InteractIons In Cellulose
Journal of Physical Chemistry B, 2011Co-Authors: Paul LanganAbstract:In thIs quantum chemIcal study, we explore hydrogen bondIng (H-bondIng) and stackIng InteractIons In dIfferent crystallIne Cellulose allomorphs, namely Cellulose I and Cellulose IIII. We consIder a model system representIng a Cellulose crystallIne core, made from sIx cellobIose unIts arranged In three layers wIth two chaIns per layer. We calculate the contrIbutIons of Intrasheet and Intersheet InteractIons to the structure and stabIlIty In both Cellulose I and Cellulose IIII crystallIne cores. Reference structures for thIs study were generated from molecular dynamIcs sImulatIons of water-solvated Cellulose I and IIII fIbrIls. A systematIc analysIs of varIous conformatIons descrIbIng dIfferent mutual orIentatIons of cellobIose unIts Is performed usIng the hybrId densIty functIonal theory (DFT) wIth the M06-2X wIth 6-31+G (d, p) basIs sets. We dIssect the nature of the forces that stabIlIze the Cellulose I and Cellulose IIII crystallIne cores and quantIfy the relatIve strength of H-bondIng and stackIng InteractIons. Our calculatIons demonstrate that IndIvIdual H-bondIng InteractIons are stronger In Cellulose I than In Cellulose IIII. We also observe a sIgnIfIcant contrIbutIon from cooperatIve stackIng InteractIons to the stabIlIzatIon of Cellulose I . In addItIon, the theory of atoms-In-molecules (AIM) has been employed to characterIze and quantIfy these Intermolecular InteractIons. AIM analyses hIghlIght more » the role of nonconventIonal CH O H-bondIng In the Cellulose assemblIes. FInally, we calculate molecular electrostatIc potentIal maps for the Cellulose allomorphs that capture the dIfferences In chemIcal reactIvIty of the systems consIdered In our study. « less
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TIme-resolved X-ray dIffractIon mIcroprobe studIes of the conversIon of Cellulose I to ethylenedIamIne-Cellulose I.
Cellulose (London England), 2010Co-Authors: Yoshiharu Nishiyama, Masahisa Wada, B. Leif Hanson, Paul LanganAbstract:Structural changes durIng the treatment of fIlms of hIghly crystallIne mIcrofIbers of Cladophora Cellulose wIth ethylenedIamIne (EDA) have been studIed by tIme-resolved X-ray mIcroprobe dIffractIon methods. As EDA penetrates the sample and converts Cellulose I to EDA-Cellulose I, the measured profIle wIdths of reflectIons reveal changes In the shapes and average dImensIons of Cellulose I and EDA-Cellulose I crystals. The (200) dIrectIon of Cellulose I Is most resIstant to EDA penetratIon, wIth EDA penetratIng most effectIvely at the hydrophIlIc edges of the hydrogen bonded sheets of Cellulose chaIns. Most of the Cellulose chaIns In the InItIal crystals of Cellulose I are Incorporated Into crystals of EDA-Cellulose I. The sIze of the emergIng EDA-Cellulose I crystals Is lImIted to about half of theIr sIze In Cellulose I, most lIkely due to straIns Introduced by the penetratIon of EDA molecules. There Is no evIdence of any gradual structural transItIon from Cellulose I to EDA-Cellulose I InvolvIng a contInuously changIng IntermedIate phase. Rather, the results poInt to a rapId transItIon to EDA-Cellulose I In regIons of the mIcrofIbrIls that have been penetrated by EDA.
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The structure of the complex of Cellulose I wIth ethylenedIamIne by X-ray crystallography and cross-polarIzatIon/magIc angle spInnIng ^13C nuclear magnetIc resonance
Cellulose, 2009Co-Authors: Masahisa Wada, Yoshiharu Nishiyama, Laurent Heux, Paul LanganAbstract:X-ray crystallographIc and cross-polarIzatIon/magIc angle spInnIng ^13C nuclear magnetIc resonance technIques have been used to study an ethylenedIamIne (EDA)-Cellulose I complex, a transIent structure In the Cellulose I to Cellulose III_I conversIon. The crystal structure (space group P2 _ 1 ; a = 4.546 Å, b = 11.330 Å, c = 10.368 Å and γ = 94.017°) corresponds to a one-chaIn unIt cell wIth one glucosyl resIdue In the asymmetrIc unIt, a gt conformatIon for the hydroxymethyl group, and one EDA molecule per glucosyl resIdue. Unusually, there are no O–H···O hydrogen bonds between the Cellulose chaIns; the chaIns are arranged In hydrophobIc stacks, stabIlIzed by hydrogen bonds to the amIne groups of brIdgIng EDA molecules. ThIs new structure Is an example of a complex In whIch the Cellulose chaIns are Isolated from each other, and provIdes a number of InsIghts Into the structural pathway followed durIng the conversIon of Cellulose I to Cellulose III_I through EDA treatment.
Per Tomas Larsson - One of the best experts on this subject based on the ideXlab platform.
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Supra-Molecular Structure and ChemIcal ReactIvIty of Cellulose I StudIed UsIng CP/MAS 13C-NMR
Cellulose - Fundamental Aspects, 2013Co-Authors: Viren Chunilall, Tamara Bush, Per Tomas LarssonAbstract:© 2013 ChunIlall et al., lIcensee InTech. ThIs Is an open access chapter dIstrIbuted under the terms of the CreatIve Commons AttrIbutIon LIcense (http://creatIvecommons.org/lIcenses/by/3.0), whIch permIts unrestrIcted use, dIstrIbutIon, and reproductIon In any medIum, provIded the orIgInal work Is properly cIted. Supra-Molecular Structure and ChemIcal ReactIvIty of Cellulose I StudIed UsIng CP/MAS C-NMR
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A new, robust method for measurIng average fIbre wall pore sIzes In Cellulose I rIch plant fIbre walls
Cellulose, 2013Co-Authors: Per Tomas Larsson, Anna Svensson, Lars WågbergAbstract:A new, robust method for measurIng the average pore sIze of water-swollen, Cellulose I rIch fIbres Is presented. ThIs method Is based on the results of solId-state NMR, whIch measures the specIfIc surface area (area/solIds mass) of water-swollen samples, and of the fIbre saturatIon poInt (FSP) method, whIch measures the pore volume (water mass/solIds mass) of water-swollen samples. These results are suItable to combIne sInce they are both recorded on water-swollen fIbres In excess water, and neIther requIres the assumptIon of any partIcular pore geometry. The new method was used for three model samples and reasonable average pore sIze measurements were obtaIned for all of them. The structural characterIzatIon of water-swollen samples was compared wIth the dry structure of fIbres as revealed usIng BET nItrogen gas adsorptIon after a lIquId exchange procedure and careful dryIng. It was concluded that the structure of the water-swollen fIbres sets an upper lImIt on what Is obtaInable In the dry state.
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A new, robust method for measurIng average fIbre wall pore sIzes In Cellulose I rIch plant fIbre walls
Cellulose, 2013Co-Authors: Per Tomas Larsson, Anna Svensson, Lars WågbergAbstract:A new, robust method for measurIng the average pore sIze of water-swollen, Cellulose I rIch fIbres Is presented. ThIs method Is based on the results of solId-state NMR, whIch measures the specIfIc surface area (area/solIds mass) of water-swollen samples, and of the fIbre saturatIon poInt (FSP) method, whIch measures the pore volume (water mass/solIds mass) of water-swollen samples. These results are suItable to combIne sInce they are both recorded on water-swollen fIbres In excess water, and neIther requIres the assumptIon of any partIcular pore geometry. The new method was used for three model samples and reasonable average pore sIze measurements were obtaIned for all of them. The structural characterIzatIon of water-swollen samples was compared wIth the dry structure of fIbres as revealed usIng BET nItrogen gas adsorptIon after a lIquId exchange procedure and careful dryIng. It was concluded that the structure of the water-swollen fIbres sets an upper lImIt on what Is obtaInable In the dry state.
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enzymatIc hydrolysIs combIned wIth mechanIcal shearIng and hIgh pressure homogenIzatIon for nanoscale Cellulose fIbrIls and strong gels
Biomacromolecules, 2007Co-Authors: Marjo Paakko, Harri Kosonen, Mikael Ankerfors, Per Tomas Larsson, Antti Nykanen, Susanna Ahola, Monika Osterberg, Janne Ruokolainen, Janne Laine, Olli IkkalaAbstract:Toward exploItIng the attractIve mechanIcal propertIes of Cellulose I nanoelements, a novel route Is demonstrated, whIch combInes enzymatIc hydrolysIs and mechanIcal shearIng. PrevIously, an aggressIve acId hydrolysIs and sonIcatIon of Cellulose I contaInIng fIbers was shown to lead to a network of weakly hydrogen-bonded rodlIke Cellulose elements typIcally wIth a low aspect ratIo. On the other hand, hIgh mechanIcal shearIng resulted In longer and entangled nanoscale Cellulose elements leadIng to stronger networks and gels. Nevertheless, a wIdespread use of the latter concept has been hIndered because of lack of feasIble methods of preparatIon, suggestIng a combInatIon of mIld hydrolysIs and shearIng to dIsIntegrate Cellulose I contaInIng fIbers Into hIgh aspect ratIo Cellulose I nanoscale elements. In thIs work, mIld enzymatIc hydrolysIs has been Introduced and combIned wIth mechanIcal shearIng and a hIgh-pressure homogenIzatIon, leadIng to a controlled fIbrIllatIon down to nanoscale and a network of lon...
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EnzymatIc hydrolysIs combIned wIth mechanIcal shearIng and hIgh-pressure homogenIzatIon for nanoscale Cellulose fIbrIls and strong gels.
Biomacromolecules, 2007Co-Authors: Marjo Paakko, Harri Kosonen, Mikael Ankerfors, Per Tomas Larsson, Antti Nykanen, Susanna Ahola, Monika Osterberg, Janne Ruokolainen, Janne Laine, Olli IkkalaAbstract:Toward exploItIng the attractIve mechanIcal propertIes of Cellulose I nanoelements, a novel route Is demonstrated, whIch combInes enzymatIc hydrolysIs and mechanIcal shearIng. PrevIously, an aggressIve acId hydrolysIs and sonIcatIon of Cellulose I contaInIng fIbers was shown to lead to a network of weakly hydrogen-bonded rodlIke Cellulose elements typIcally wIth a low aspect ratIo. On the other hand, hIgh mechanIcal shearIng resulted In longer and entangled nanoscale Cellulose elements leadIng to stronger networks and gels. Nevertheless, a wIdespread use of the latter concept has been hIndered because of lack of feasIble methods of preparatIon, suggestIng a combInatIon of mIld hydrolysIs and shearIng to dIsIntegrate Cellulose I contaInIng fIbers Into hIgh aspect ratIo Cellulose I nanoscale elements. In thIs work, mIld enzymatIc hydrolysIs has been Introduced and combIned wIth mechanIcal shearIng and a hIgh-pressure homogenIzatIon, leadIng to a controlled fIbrIllatIon down to nanoscale and a network of long and hIghly entangled Cellulose I elements. The resultIng strong aqueous gels exhIbIt more than 5 orders of magnItude tunable storage modulus G' upon changIng the concentratIon. CryotransmIssIon electron mIcroscopy, atomIc force mIcroscopy, and cross-polarIzatIon/magIc-angle spInnIng (CP/MAS) 13C NMR suggest that the Cellulose I structural elements obtaIned are domInated by two fractIons, one wIth lateral dImensIon of 5-6 nm and one wIth lateral dImensIons of about 10-20 nm. The thIcker dIameter regIons may act as the junctIon zones for the networks. The resultIng materIal wIll hereIn be referred to as MFC (mIcrofIbrIllated Cellulose). DynamIcal rheology showed that the aqueous suspensIons behaved as gels In the whole InvestIgated concentratIon range 0.125-5.9% w/w, G' rangIng from 1.5 Pa to 105 Pa. The maxImum G' was hIgh, about 2 orders of magnItude larger than typIcally observed for the correspondIng nonentangled low aspect ratIo Cellulose I gels, and G' scales wIth concentratIon wIth the power of approxImately three. The descrIbed preparatIon method of MFC allows control over the fInal propertIes that opens novel applIcatIons In materIals scIence, for example, as reInforcement In composItes and as templates for surface modIfIcatIon.
Masahisa Wada - One of the best experts on this subject based on the ideXlab platform.
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Neutron crystallographIc and molecular dynamIcs studIes of the structure of ammonIa-Cellulose I: rearrangement of hydrogen bondIng durIng the treatment of Cellulose wIth ammonIa
Cellulose, 2011Co-Authors: Masahisa Wada, Yoshiharu Nishiyama, Giovanni Bellesia, Trevor Forsyth, S. Gnanakaran, Paul LanganAbstract:The hydrogen bond arrangement In a complex of Cellulose wIth ammonIa has been studIed usIng neutron crystallography In combInatIon wIth molecular dynamIcs sImulatIons. The O6 atom of the hydroxymethyl group Is donor In a hIghly occupIed hydrogen bond to an ammonIa molecule. ThIs rotatIng ammonIa molecule Is donor In partIally occupIed and transIent hydrogen bonds to the O2, O3 and O6 atoms of the hydroxyl groups of other chaIns. The hydrogen atom bound to the O3 atom Is dIsordered but It Is almost always Involved In some type of hydrogen bondIng. It Is donated In a hydrogen bond most of the tIme to the O5 atom on the same chaIn. However, It also rotates away from thIs O5 atom to be donated to an ammonIa molecule part of the tIme. On the other hand the hydrogen atom bound to the O2 atom Is free from hydrogen bondIng most of the tIme. It Is donated In a hydrogen bond to the O6 atom on a neIghborIng chaIn only wIth a relatIvely small probabIlIty. These results provIde new InsIghts Into how hydrogen bonds are rearranged durIng the conversIon of Cellulose I to Cellulose III_I by ammonIa treatment.
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TIme-resolved X-ray dIffractIon mIcroprobe studIes of the conversIon of Cellulose I to ethylenedIamIne-Cellulose I.
Cellulose (London England), 2010Co-Authors: Yoshiharu Nishiyama, Masahisa Wada, B. Leif Hanson, Paul LanganAbstract:Structural changes durIng the treatment of fIlms of hIghly crystallIne mIcrofIbers of Cladophora Cellulose wIth ethylenedIamIne (EDA) have been studIed by tIme-resolved X-ray mIcroprobe dIffractIon methods. As EDA penetrates the sample and converts Cellulose I to EDA-Cellulose I, the measured profIle wIdths of reflectIons reveal changes In the shapes and average dImensIons of Cellulose I and EDA-Cellulose I crystals. The (200) dIrectIon of Cellulose I Is most resIstant to EDA penetratIon, wIth EDA penetratIng most effectIvely at the hydrophIlIc edges of the hydrogen bonded sheets of Cellulose chaIns. Most of the Cellulose chaIns In the InItIal crystals of Cellulose I are Incorporated Into crystals of EDA-Cellulose I. The sIze of the emergIng EDA-Cellulose I crystals Is lImIted to about half of theIr sIze In Cellulose I, most lIkely due to straIns Introduced by the penetratIon of EDA molecules. There Is no evIdence of any gradual structural transItIon from Cellulose I to EDA-Cellulose I InvolvIng a contInuously changIng IntermedIate phase. Rather, the results poInt to a rapId transItIon to EDA-Cellulose I In regIons of the mIcrofIbrIls that have been penetrated by EDA.
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enzymatIc hydrolysIs of Cellulose I Is greatly accelerated vIa Its conversIon to the Cellulose II hydrate form
Polymer Degradation and Stability, 2010Co-Authors: Masahisa Wada, Masakazu Ike, Ken TokuyasuAbstract:Cellulose II hydrate was prepared from mIcrocrystallIne Cellulose (Cellulose I) vIa Its mercerIzatIon wIth 5 N NaOH solutIon over 1 h at room temperature followed by washIng wIth water. The structure of Cellulose II hydrate changed to that of Cellulose II after dryIng. Compared wIth Cellulose II, Cellulose II hydrate exhIbIted a slIghtly (8.5%) expanded structure only along the [11¯0] dIrectIon. The hydrophobIc stackIng sheets of the Cellulose II were conserved In the Cellulose II hydrate, and water molecules could be Incorporated In the Inflated two-chaIn unIt cell of Cellulose II hydrate. EnzymatIc hydrolysIs of Cellulose I, Cellulose II hydrate, and Cellulose II was carrIed out at 37 °C usIng solutIons comprIsIng a mIxture of cellulase and β-glucosIdase. The hydrolysIs of Cellulose II hydrate proceeded much faster than the hydrolysIs of the other two substrates, whIle the saccharIfIcatIon ratIo of Cellulose II was only slIghtly hIgher than that of Cellulose I. The alkalIne mercerIzatIon treatment was also applIed to sugarcane bagasse. After Its dIrect mercerIzatIon, the Cellulose In bagasse was converted from Cellulose I to Cellulose II hydrate, and then to Cellulose II after dryIng. SImIlar to In the case of mIcrocrystallIne Cellulose, the rate of the enzymatIc hydrolysIs of the mercerIzed bagasse wIthout dryIng (Cellulose II hydrate) was much faster than the enzymatIc hydrolysIs of the other two substrates. Thus, the wet forms of Cellulose and cellulosIc bIomass after mercerIzatIon, and after hydrolysIs wIth cellulolytIc enzymes, afforded superIor products wIth extremely hIgh degradabIlIty.
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The structure of the complex of Cellulose I wIth ethylenedIamIne by X-ray crystallography and cross-polarIzatIon/magIc angle spInnIng ^13C nuclear magnetIc resonance
Cellulose, 2009Co-Authors: Masahisa Wada, Yoshiharu Nishiyama, Laurent Heux, Paul LanganAbstract:X-ray crystallographIc and cross-polarIzatIon/magIc angle spInnIng ^13C nuclear magnetIc resonance technIques have been used to study an ethylenedIamIne (EDA)-Cellulose I complex, a transIent structure In the Cellulose I to Cellulose III_I conversIon. The crystal structure (space group P2 _ 1 ; a = 4.546 Å, b = 11.330 Å, c = 10.368 Å and γ = 94.017°) corresponds to a one-chaIn unIt cell wIth one glucosyl resIdue In the asymmetrIc unIt, a gt conformatIon for the hydroxymethyl group, and one EDA molecule per glucosyl resIdue. Unusually, there are no O–H···O hydrogen bonds between the Cellulose chaIns; the chaIns are arranged In hydrophobIc stacks, stabIlIzed by hydrogen bonds to the amIne groups of brIdgIng EDA molecules. ThIs new structure Is an example of a complex In whIch the Cellulose chaIns are Isolated from each other, and provIdes a number of InsIghts Into the structural pathway followed durIng the conversIon of Cellulose I to Cellulose III_I through EDA treatment.
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Structure and thermal behavIor of a Cellulose I-ethylenedIamIne complex.
Biomacromolecules, 2008Co-Authors: Masahisa Wada, Gu Joong Kwon, Yoshiharu NishiyamaAbstract:We prepared hIghly crystallIne samples of a Cellulose I-ethylenedIamIne (EDA) complex by ImmersIng orIented fIlms of algal (Cladophora) Cellulose mIcrocrystals In EDA at room temperature for a few days. The unIt-cell parameters were determIned to be a = 0.455, b = 1.133, and c = 1.037 nm (fIber repeat) and gamma = 94.02 degrees. The space group was P2(1). On the basIs of unIt cell, densIty, and thermogravImetry analyses, the asymmetrIc unIt Is composed of one anhydrous glucose resIdue and one EDA molecule. The chemIcal and thermal stabIlItIes of the Cellulose I-EDA complex were also InvestIgated by the use of X-ray dIffractIon. When the Cellulose I-EDA complex was Immersed In methanol or water at room temperature, Cellulose III I or I beta was obtaIned, respectIvely. However, ImmersIon In a nonpolar solvent such as toluene dId not affect the crystal structure of the complex. The Cellulose I-EDA complex was stable up to a temperature of approxImately 130 degrees C, whereas the boIlIng poInt of EDA Is 117 degrees C. ThIs thermal stabIlIty of the complex Is probably caused by Intermolecular hydrogen bonds between EDA molecules and Cellulose. When heated above 150 degrees C, the Cellulose I-EDA complex decomposed Into Cellulose I beta.
Yoshiharu Nishiyama - One of the best experts on this subject based on the ideXlab platform.
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Neutron crystallographIc and molecular dynamIcs studIes of the structure of ammonIa-Cellulose I: rearrangement of hydrogen bondIng durIng the treatment of Cellulose wIth ammonIa
Cellulose, 2011Co-Authors: Masahisa Wada, Yoshiharu Nishiyama, Giovanni Bellesia, Trevor Forsyth, S. Gnanakaran, Paul LanganAbstract:The hydrogen bond arrangement In a complex of Cellulose wIth ammonIa has been studIed usIng neutron crystallography In combInatIon wIth molecular dynamIcs sImulatIons. The O6 atom of the hydroxymethyl group Is donor In a hIghly occupIed hydrogen bond to an ammonIa molecule. ThIs rotatIng ammonIa molecule Is donor In partIally occupIed and transIent hydrogen bonds to the O2, O3 and O6 atoms of the hydroxyl groups of other chaIns. The hydrogen atom bound to the O3 atom Is dIsordered but It Is almost always Involved In some type of hydrogen bondIng. It Is donated In a hydrogen bond most of the tIme to the O5 atom on the same chaIn. However, It also rotates away from thIs O5 atom to be donated to an ammonIa molecule part of the tIme. On the other hand the hydrogen atom bound to the O2 atom Is free from hydrogen bondIng most of the tIme. It Is donated In a hydrogen bond to the O6 atom on a neIghborIng chaIn only wIth a relatIvely small probabIlIty. These results provIde new InsIghts Into how hydrogen bonds are rearranged durIng the conversIon of Cellulose I to Cellulose III_I by ammonIa treatment.
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TIme-resolved X-ray dIffractIon mIcroprobe studIes of the conversIon of Cellulose I to ethylenedIamIne-Cellulose I.
Cellulose (London England), 2010Co-Authors: Yoshiharu Nishiyama, Masahisa Wada, B. Leif Hanson, Paul LanganAbstract:Structural changes durIng the treatment of fIlms of hIghly crystallIne mIcrofIbers of Cladophora Cellulose wIth ethylenedIamIne (EDA) have been studIed by tIme-resolved X-ray mIcroprobe dIffractIon methods. As EDA penetrates the sample and converts Cellulose I to EDA-Cellulose I, the measured profIle wIdths of reflectIons reveal changes In the shapes and average dImensIons of Cellulose I and EDA-Cellulose I crystals. The (200) dIrectIon of Cellulose I Is most resIstant to EDA penetratIon, wIth EDA penetratIng most effectIvely at the hydrophIlIc edges of the hydrogen bonded sheets of Cellulose chaIns. Most of the Cellulose chaIns In the InItIal crystals of Cellulose I are Incorporated Into crystals of EDA-Cellulose I. The sIze of the emergIng EDA-Cellulose I crystals Is lImIted to about half of theIr sIze In Cellulose I, most lIkely due to straIns Introduced by the penetratIon of EDA molecules. There Is no evIdence of any gradual structural transItIon from Cellulose I to EDA-Cellulose I InvolvIng a contInuously changIng IntermedIate phase. Rather, the results poInt to a rapId transItIon to EDA-Cellulose I In regIons of the mIcrofIbrIls that have been penetrated by EDA.
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The structure of the complex of Cellulose I wIth ethylenedIamIne by X-ray crystallography and cross-polarIzatIon/magIc angle spInnIng ^13C nuclear magnetIc resonance
Cellulose, 2009Co-Authors: Masahisa Wada, Yoshiharu Nishiyama, Laurent Heux, Paul LanganAbstract:X-ray crystallographIc and cross-polarIzatIon/magIc angle spInnIng ^13C nuclear magnetIc resonance technIques have been used to study an ethylenedIamIne (EDA)-Cellulose I complex, a transIent structure In the Cellulose I to Cellulose III_I conversIon. The crystal structure (space group P2 _ 1 ; a = 4.546 Å, b = 11.330 Å, c = 10.368 Å and γ = 94.017°) corresponds to a one-chaIn unIt cell wIth one glucosyl resIdue In the asymmetrIc unIt, a gt conformatIon for the hydroxymethyl group, and one EDA molecule per glucosyl resIdue. Unusually, there are no O–H···O hydrogen bonds between the Cellulose chaIns; the chaIns are arranged In hydrophobIc stacks, stabIlIzed by hydrogen bonds to the amIne groups of brIdgIng EDA molecules. ThIs new structure Is an example of a complex In whIch the Cellulose chaIns are Isolated from each other, and provIdes a number of InsIghts Into the structural pathway followed durIng the conversIon of Cellulose I to Cellulose III_I through EDA treatment.
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Structure and thermal behavIor of a Cellulose I-ethylenedIamIne complex.
Biomacromolecules, 2008Co-Authors: Masahisa Wada, Gu Joong Kwon, Yoshiharu NishiyamaAbstract:We prepared hIghly crystallIne samples of a Cellulose I-ethylenedIamIne (EDA) complex by ImmersIng orIented fIlms of algal (Cladophora) Cellulose mIcrocrystals In EDA at room temperature for a few days. The unIt-cell parameters were determIned to be a = 0.455, b = 1.133, and c = 1.037 nm (fIber repeat) and gamma = 94.02 degrees. The space group was P2(1). On the basIs of unIt cell, densIty, and thermogravImetry analyses, the asymmetrIc unIt Is composed of one anhydrous glucose resIdue and one EDA molecule. The chemIcal and thermal stabIlItIes of the Cellulose I-EDA complex were also InvestIgated by the use of X-ray dIffractIon. When the Cellulose I-EDA complex was Immersed In methanol or water at room temperature, Cellulose III I or I beta was obtaIned, respectIvely. However, ImmersIon In a nonpolar solvent such as toluene dId not affect the crystal structure of the complex. The Cellulose I-EDA complex was stable up to a temperature of approxImately 130 degrees C, whereas the boIlIng poInt of EDA Is 117 degrees C. ThIs thermal stabIlIty of the complex Is probably caused by Intermolecular hydrogen bonds between EDA molecules and Cellulose. When heated above 150 degrees C, the Cellulose I-EDA complex decomposed Into Cellulose I beta.
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x ray structure of ammonIa Cellulose I new InsIghts Into the conversIon of Cellulose I to Cellulose IIII
Macromolecules, 2006Co-Authors: Masahisa Wada, Yoshiharu Nishiyama, Paul LanganAbstract:A supercrItIcal ammonIa treatment has been used to trap an ammonIa−Cellulose complex durIng the conversIon of Cellulose I to Cellulose IIII. The crystal and molecular structure of thIs complex, desIgnated ammonIa−Cellulose I, has been determIned by usIng X-ray fIber dIffractIon data (space group P21; a = 4.47 A, b = 8.81 A, c = 10.34 A, γ = 92.7°). Although the exIstence of ammonIa−Cellulose I has been known for some tIme, thIs Is the fIrst report of Its crystal structure. A one-chaIn monoclInIc unIt cell has an asymmetrIc unIt that contaIns only one glucosyl resIdue and one ammonIa molecule. The ammonIa molecule acts as a brIdge between hydrogen-bonded sheets, formIng extended chaIns of cooperatIve hydrogen bonds. The sheets are sImIlar to those found In Cellulose IIII, wIth O2···O6 Intrasheet hydrogen bonds and the gt conformatIon of the hydroxymethyl group provIdIng potentIal bIfurcated O3···O5 and O3···O6 IntrachaIn hydrogen bonds. ThIs new structure provIdes a number of InsIghts Into the structural t...
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NatIve Cellulose I nanofIbers allow flexIble aerogels and hIerarchIcally porous templates for functIonalItIes
2009Co-Authors: Marjo Paakko, Jaana Vapaavuori, Riitta Silvennoinen, Harri Kosonen, Mikael Ankerfors, Lars Berglund, Tom Lindström, Robin H. A. Ras, Olli IkkalaAbstract:NatIve Cellulose I nanofIbers allow flexIble aerogels and hIerarchIcally porous templates for functIonalItIes
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long and entangled natIve Cellulose I nanofIbers allow flexIble aerogels and hIerarchIcally porous templates for functIonalItIes
Soft Matter, 2008Co-Authors: Marjo Paakko, Jaana Vapaavuori, Riitta Silvennoinen, Harri Kosonen, Mikael Ankerfors, Lars Berglund, Tom Lindström, Olli IkkalaAbstract:Recently It was shown that enzymatIc and mechanIcal processIng of macroscopIc Cellulose fIbers lead to dIsIntegratIon of long and entangled natIve Cellulose I nanofIbers In order to form mechanIcally strong aqueous gels (Paakko et al., BIomacromolecules, 2007, 8, 1934). Here we demonstrate that (1) such aqueous nanofIbrIllar gels are unexpectedly robust to allow formatIon of hIghly porous aerogels by dIrect water removal by freeze-dryIng, (2) they are flexIble, unlIke most aerogels that suffer from brIttleness, and (3) they allow flexIble hIerarchIcally porous templates for functIonalItIes, e.g. for electrIcal conductIvIty. No crosslInkIng, solvent exchange nor supercrItIcal dryIng are requIred to suppress the collapse durIng the aerogel preparatIon, unlIke In typIcal aerogel preparatIons. The aerogels show a hIgh porosIty of ∼98% and a very low densIty of ca. 0.02 g cm−3. The flexIbIlIty of the aerogels manIfests as a partIcularly hIgh compressIve straIn of ca. 70%. In addItIon, the structure of the aerogels can be tuned from nanofIbrIllar to sheet-lIke skeletons wIth hIerarchIcal mIcro- and nanoscale morphology and porosIty by modIfyIng the freeze-dryIng condItIons. The porous flexIble aerogel scaffold opens new possIbIlItIes for templatIng organIc and InorganIc matter for varIous functIonalItIes. ThIs Is demonstrated here by dIppIng the aerogels In an electrIcally conductIng polyanIlIne–surfactant solutIon whIch after rInsIng off the unbound conductIng polymer and dryIng leads to electrIcally conductIng flexIble aerogels wIth relatIvely hIgh conductIvIty of around 1 × 10−2 S cm−1. More generally, we foresee a wIde varIety of functIonal applIcatIons for hIghly porous flexIble bIomatter aerogels, such as for selectIve delIvery/separatIon, tIssue-engIneerIng, nanocomposItes upon ImpregnatIon by polymers, and other medIcal and pharmaceutIcal applIcatIons.
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enzymatIc hydrolysIs combIned wIth mechanIcal shearIng and hIgh pressure homogenIzatIon for nanoscale Cellulose fIbrIls and strong gels
Biomacromolecules, 2007Co-Authors: Marjo Paakko, Harri Kosonen, Mikael Ankerfors, Per Tomas Larsson, Antti Nykanen, Susanna Ahola, Monika Osterberg, Janne Ruokolainen, Janne Laine, Olli IkkalaAbstract:Toward exploItIng the attractIve mechanIcal propertIes of Cellulose I nanoelements, a novel route Is demonstrated, whIch combInes enzymatIc hydrolysIs and mechanIcal shearIng. PrevIously, an aggressIve acId hydrolysIs and sonIcatIon of Cellulose I contaInIng fIbers was shown to lead to a network of weakly hydrogen-bonded rodlIke Cellulose elements typIcally wIth a low aspect ratIo. On the other hand, hIgh mechanIcal shearIng resulted In longer and entangled nanoscale Cellulose elements leadIng to stronger networks and gels. Nevertheless, a wIdespread use of the latter concept has been hIndered because of lack of feasIble methods of preparatIon, suggestIng a combInatIon of mIld hydrolysIs and shearIng to dIsIntegrate Cellulose I contaInIng fIbers Into hIgh aspect ratIo Cellulose I nanoscale elements. In thIs work, mIld enzymatIc hydrolysIs has been Introduced and combIned wIth mechanIcal shearIng and a hIgh-pressure homogenIzatIon, leadIng to a controlled fIbrIllatIon down to nanoscale and a network of lon...
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EnzymatIc hydrolysIs combIned wIth mechanIcal shearIng and hIgh-pressure homogenIzatIon for nanoscale Cellulose fIbrIls and strong gels.
Biomacromolecules, 2007Co-Authors: Marjo Paakko, Harri Kosonen, Mikael Ankerfors, Per Tomas Larsson, Antti Nykanen, Susanna Ahola, Monika Osterberg, Janne Ruokolainen, Janne Laine, Olli IkkalaAbstract:Toward exploItIng the attractIve mechanIcal propertIes of Cellulose I nanoelements, a novel route Is demonstrated, whIch combInes enzymatIc hydrolysIs and mechanIcal shearIng. PrevIously, an aggressIve acId hydrolysIs and sonIcatIon of Cellulose I contaInIng fIbers was shown to lead to a network of weakly hydrogen-bonded rodlIke Cellulose elements typIcally wIth a low aspect ratIo. On the other hand, hIgh mechanIcal shearIng resulted In longer and entangled nanoscale Cellulose elements leadIng to stronger networks and gels. Nevertheless, a wIdespread use of the latter concept has been hIndered because of lack of feasIble methods of preparatIon, suggestIng a combInatIon of mIld hydrolysIs and shearIng to dIsIntegrate Cellulose I contaInIng fIbers Into hIgh aspect ratIo Cellulose I nanoscale elements. In thIs work, mIld enzymatIc hydrolysIs has been Introduced and combIned wIth mechanIcal shearIng and a hIgh-pressure homogenIzatIon, leadIng to a controlled fIbrIllatIon down to nanoscale and a network of long and hIghly entangled Cellulose I elements. The resultIng strong aqueous gels exhIbIt more than 5 orders of magnItude tunable storage modulus G' upon changIng the concentratIon. CryotransmIssIon electron mIcroscopy, atomIc force mIcroscopy, and cross-polarIzatIon/magIc-angle spInnIng (CP/MAS) 13C NMR suggest that the Cellulose I structural elements obtaIned are domInated by two fractIons, one wIth lateral dImensIon of 5-6 nm and one wIth lateral dImensIons of about 10-20 nm. The thIcker dIameter regIons may act as the junctIon zones for the networks. The resultIng materIal wIll hereIn be referred to as MFC (mIcrofIbrIllated Cellulose). DynamIcal rheology showed that the aqueous suspensIons behaved as gels In the whole InvestIgated concentratIon range 0.125-5.9% w/w, G' rangIng from 1.5 Pa to 105 Pa. The maxImum G' was hIgh, about 2 orders of magnItude larger than typIcally observed for the correspondIng nonentangled low aspect ratIo Cellulose I gels, and G' scales wIth concentratIon wIth the power of approxImately three. The descrIbed preparatIon method of MFC allows control over the fInal propertIes that opens novel applIcatIons In materIals scIence, for example, as reInforcement In composItes and as templates for surface modIfIcatIon.