The effect of precipitation on the molecular weight distribution of cellulose tricarbanilate

Wood, B. F.; Conner, Anthony H.; Hill, Charles G.

doi:10.1002/app.1986.070320225

Cited by 68 publications

(35 citation statements)

References 6 publications

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“…Similar to that in the determination of the molecular weight of polysaccharides [29,30], phenylcarbamoylation does not affect the molecular weight distribution of the original sample. Furthermore, the present phenylcarbamoylation reaction was performed at room temperature in DMSO, and almost no decomposition was considered to occur.…”

Section: Resultsmentioning

confidence: 79%

Strongly thixotropic viscosity behavior of dimethylsulfoxide solution of polyrotaxane comprising α-cyclodextrin and low molecular weight poly(ethylene glycol)

Araki

Ito

2007

Polymer

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A strong thixotropic viscosity behavior was observed when polyrotaxane prepared from α-cyclodextrins (CDs) and poly(ethylene glycol) (PEG) with a molecular weight of 2000 was dissolved in dimethylsulfoxide (DMSO). A 10 wt% solution liquefied by vigorous shaking was rapidly gelated by standing --this sol-gel transition was reversible. The time for recovering the viscosity was dependent on the polyrotaxane concentration, i.e., a 10wt% solution regelated within 30 s, whereas several hours were required for the gelation of a 2.5wt% solution. The thixotropic nature of the solution was also confirmed by the clockwise hysteresis curve of the viscosity when the shear rate was increased and decreased. The gel permeation chromatography (GPC) measurement of the polyrotaxane in DMSO exhibited peaks in the high molecular weight region. The peak disappeared after the phenylcarbamoylation of polyrotaxane, suggesting that the peak was due to loose aggregations of polyrotaxane in DMSO. On the other hand, the DMSO solution of polyrotaxane prepared from CD and PEG with a molecular weight of 3350-whose inclusion ratio (51%) is slightly lower than that of PEG2000 polyrotaxane (72%)-neither demonstrated the abovementioned thixotropic viscosity nor the peak corresponding to the aggregations occurring during the GPC measurement. The thixotropic behavior was speculated to be caused by the combined contribution of intermolecular attractive hydrogen bonding and higher rigidity of polyrotaxane prepared from PEG 2000 than that of polyrotaxane prepared from PEG3350, presumably due to the higher inclusion ratio of the former than that of the latter. Key Word: Polyrotaxane, Thixotropy, intermolecular hydrogen bonding 2 INTRODUCTIONPolyrotaxane is a typical supramolecular material that possesses linear molecule threading through many cyclic molecules, which can freely slide or rotate over the linear molecule [1][2][3][4]. Great advances have been made in the investigation of polyrotaxane since the discovery of the formation of pseudopolyrotaxane by the spontaneous inclusion complexation of cyclodextrins (CDs) and linear polymers by Harada et al. [5][6][7][8][9]. The formation of the inclusion complex with CDs and various linear polymers via spontaneous self-assembly was thoroughly investigated by Harada et al. [1,5,6], who successfully prepared polyrotaxane by binding bulky end groups (such as dinitrophenyl moieties) to the ends of pseudopolyrotaxane, i.e., the inclusion complex of CDs and PEG [7][8][9]. A wide variety of attractive concepts have been reported to date after the first finding by Harada, such as the preparation of a "molecular tube" by cross-linking adjacent CDs in single polyrotaxane followed by the dissociation of the included PEG [10], an insulated molecular wire comprising a conducting polymer and a molecular tube [11,12], a drug delivery system using polyrotaxane carrying drugs on the CD moiety [13], multivalent ligand system [14], the construction of an energy transfer system using polyrotaxane with photoluminescent...

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Section: Resultsmentioning

confidence: 79%

Strongly thixotropic viscosity behavior of dimethylsulfoxide solution of polyrotaxane comprising α-cyclodextrin and low molecular weight poly(ethylene glycol)

Araki

Ito

2007

Polymer

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“…6 [59]. The PIC derivatization reaction has been used to make carbamate derivatives of cellulose for analysis by SEC, and of amylose and cellulose for use as chiral stationary phases [6,59,60,67,68]. Therefore, these reactions have been well characterized.…”

Section: Nonaqueous Seec Of Polysaccharidesmentioning

confidence: 99%

Size‐exclusion capillary electrochromatographic separation of polysaccharides using polymeric stationary phases

2003

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We report the successful size-based separations of large, neutral polysaccharides using capillary electrochromatography (CEC). As the polysaccharides possessed little chromophore for photometric detection, two separate approaches were taken. In the first approach, indirect detection was combined with size-exclusion chromatography using a sulfonated polystyrene/divinylbenzene stationary phase. The separations were performed using a 300 Å pore size stationary phase under aqueous conditions. Nonsize based interactions were minimal using this material, resulting in an effective calibration range of molecular masses 180 to 112 000 g?mol 21 for pullulans. In the second approach, the polysaccharides were derivatized with phenylisocyanate and were subsequently separated on columns made using a combination of high capacity ionexchanger and a neutral polystyrene/divinylbenzene material of various pore sizes. The sulfonated ion-exchange phase provided the electroosmotic flow, while the mixed pore size material provided the extended calibration range. The linear range for this primarily nonaqueous system using tetrahydrofuran was determined to be from molecular masses 738 to 404 000 g?mol 21 of the original, untagged pullulan. This approach overcame the limited solubility issue associated with analysis of some polysaccharides. Analysis of pullulan and amylose samples by CEC correlated well with results obtained by conventional high-performance liquid chromatography (HPLC). The sizeexclusion electrochromatographic separations provide an alternative mode for determining the relative molecular weights of polysaccharides with reduced sample and solvent consumption, as well as analysis times.

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“…A reliable derivatization without degradation (polymer-analogous derivatization) thus could not be performed so far. Many derivatization procedures for cellulose tricarbanilates have been reported (Hall and Horne 1973;Valtasaari and Saarela 1975;Schroeder and Haigh 1979;Wood et al 1986;Lauriol et al 1987;Evans et al 1989Evans et al , 1991aTerbojevich et al 1995). In most protocols DMSO was used as the derivatization solvent, sometimes pyridine, or mixtures of both solvents.…”

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confidence: 98%

Studies on DMSO-containing carbanilation mixtures: chemistry, oxidations and cellulose integrity

et al. 2007

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The oxidative effect of carbanilation mixtures containing dimethylsulfoxide (DMSO) was demonstrated by means of alcohol model substances in which competitive carbanilation was prevented due to steric hindrance of the hydroxyl function, rendering those compounds specific probes for oxidation effects. Dimethylsulfonium ions and derived ylide species were shown to be the actually oxidizing species according to trapping methodology using lipophilic olefins which were converted into the corresponding cyclopropane and epoxide derivatives. The experimental data were in good agreement with DFT computations carried out on the B3LYP/6-311+G(d,p) level of theory. The direct interaction of cellulose and sulfoxide solvent was proven by means of methyl-(2-naphthyl)sulfoxide (MNSO) as a model for DMSO, which caused introduction of UV-detectable methylthionaphthyl ether moieties into the cellulose, formed in Pummerer-type side reaction paralleling the chemical behavior of DMSO. A facile color test-responding to sulfoxide-derived oxidizing species-was developed to assess the suitability of carbanilation conditions with regard to cellulose oxidation and degradation. DMSO-based carbanilation systems have to be used with great caution for determination of molecular weight parameters and for similar purposes which require complete maintenance of the cellulose integrity. Cellulose oxidation/ degradation by DMSO-derived intermediates upon carbanilation can be minimized but cannot be avoided completely. Thus, if cellulose integrity is an issue as it is in cellulose analytics, it is recommended to replace DMSO by solvent components of similar solution behavior but without the inherent danger of generating oxidants, such as pyridine or DMAc, whenever possible.

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The effect of precipitation on the molecular weight distribution of cellulose tricarbanilate

Cited by 68 publications

References 6 publications

Strongly thixotropic viscosity behavior of dimethylsulfoxide solution of polyrotaxane comprising α-cyclodextrin and low molecular weight poly(ethylene glycol)

Strongly thixotropic viscosity behavior of dimethylsulfoxide solution of polyrotaxane comprising α-cyclodextrin and low molecular weight poly(ethylene glycol)

Size‐exclusion capillary electrochromatographic separation of polysaccharides using polymeric stationary phases

Studies on DMSO-containing carbanilation mixtures: chemistry, oxidations and cellulose integrity

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