Properties of cellulose acetate in solution. I. Light scattering, osmometry, and viscometry on dilute solutions

Tanner, David; Berry, G. C.

doi:10.1002/pol.1974.180120508

Cited by 77 publications

(31 citation statements)

References 37 publications

(6 reference statements)

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“…22 The chain expansion of CTC with decreasing temperature was reported by several workers. [22][23][24][25][26] The values of k 0 are normal, indicating no aggregation of CTC in THF upon cooling. Figure 2 plots [] vs. M w double-logarithmically of CTC in THF at 0 and À25 C as well as the previous results at 25 C. 9 The molecular weight dependencies of [] become slightly stronger with lowering temperature.…”

Section: Resultsmentioning

confidence: 99%

Local Conformation of the Cellulosic Chain in Solution

Yanai

Sato

2006

Polym J

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ABSTRACT:The temperature and molecular weight dependencies of the intrinsic viscosity [] were investigated for cellulose tris(phenyl carbamate) (CTC) in tetrahydrofuran (THF). By the analysis of the [] data in terms of the wormlike cylinder model, the persistence length q of CTC was determined as a function of the temperature. With decreasing the temperature from 25 to À20 C, q increases from 10.5 to 13.7 nm. This temperature dependence of q was successfully explained by the broken wormlike chain model, where each glucose residue in the cellulosic chain is assumed to take left-handed 3/1 or 2/1 helical state and occasionally a kink state generated by a glucosidic bridge angle fluctuation. While the torsional fluctuation in each glucosidic bond is considerably small, there are two energetically favored helical (3/1 and 2/1) states, so that the cellulosic chain may not be regarded as a regular helix in solution. [DOI 10.1295/polymj.38.226] KEY WORDS Cellulose Derivative / Intrinsic Viscosity / Persistence Length / Broken Wormlike Chain / Local Conformation / Helicity of polymer chains plays important roles in chain rigidity, liquid crystallinity, and chiral discrimination. Recently, several synthetic polymers have been found to take more or less regular helical conformations in solution, and extensive arguments have been made on the relationship among their chemical structure, helicity, chain rigidity, liquid crystallinity, and cholesteric structure. Many review articles deal with recent advances in this subject. [1][2][3][4][5] Cellulose derivatives are known as semiflexible polymers exhibiting liquid crystallinity 6,7 and important materials in chiral chromatography.8 These features imply helical nature in the cellulosic chain. Conformations of cellulose derivatives in solution were studied both experimentally and theoretically for a long time. However, as mentioned in a previous paper, 9 their conformational analysis was not an easy task because both chain stiffness and excluded volume effect must be taken into account simultaneously due to their intermediate chain rigidity. Only recent literature provides proper analyses for the conformation of cellulosic chains 9,10 and also for solution properties (e.g., liquid crystallinity, 11 viscosity, 12 and diffusivity 13 ) based on the properly analyzed conformation. On the other hand, theoretical studies on the conformation of the cellulosic chain were carried out by Brant et al.14-17 in 1970s, who made an extensive conformational energy analysis and found two energetically stable conformations implying left-handed 3/1 and 2/1 helices for the cellulosic chain. However, the characteristic ratio C 1 and its temperature dependence estimated from their conformational energy did not satisfactorily agree with experimental results for cellulose derivatives. 15,16 The disagreement was argued occasionally afterward, 17,18 but satisfactory explanation has not been made yet. Thus, the local conformation of the cellulosic chain is still unclear.In this study, we have revisited...

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Section: Resultsmentioning

confidence: 99%

Local Conformation of the Cellulosic Chain in Solution

Yanai

Sato

2006

Polym J

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“…In a different and somewhat unusual, but not unique, example, it has been reported that Kc/R Vv (ϑ,c) is linear in q 2 , albeit giving a molecular weight that is much larger than the true value of M w for the solute. (139) This was observed with a system that formed a gel at a higher solute concentration, suggesting that the observed scattering behavior reflects the anticipated P Vv (ϑ,c) for a randomly branched polymer. (6) More frequently, with intermolecular association involving flexible chain polymers, Kc/R Vv (ϑ,c) exhibits enhanced scattering at small q.…”

Section: Intermolecular Associationmentioning

confidence: 76%

Light Scattering, Classical: Size and Size Distribution Characterization

Berry¹

2000

Encyclopedia of Analytical Chemistry

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The use of classical, or time‐averaged, light scattering methods to characterize the size and size distribution of macromolecules in dilute solutions or particles in dilute dispersions is discussed. The necessary scattering relations are presented systematically, starting with three cases at infinite dilution: the scattering extrapolated to zero angle, the scattering at small angle, and the scattering for arbitrary angle, including the inversion of the scattering data to estimate the size distribution. The relationships needed to effect an extrapolation to infinite dilution from data on dilute solutions are also discussed. These are followed by remarks on light scattering methods, and the concluding sections give examples for several applications. The Rayleigh–Gans–Debye (RGD) approximation is usually appropriate in the scattering from dilute polymer solutions and is also adequate for the scattering from dilute dispersions of small particles. The approximation is assumed when appropriate, but more complete theories are introduced where necessary, as in the use of the Mie–Lorentz theory for large spherical particles.

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“…8 The acetyl content of each fraction was determined by the alkaline hydrolysis The characteristics of the samples used in this study are summarized in Table I.…”

Section: Methodsmentioning

confidence: 99%

“…II, No. 8,1979 did not attempt to promote the crystallization of CT A and CDA films by streching or rolling, since our purpose was only to compare the X-ray diffraction pattern of the gel with that of CT A and CDA films. Although the X-ray diffraction patterns of CTA and CDA films did not show high crystallinity, the patterns nevertheless indicate that the cellulose triacetate form I crystallites 9 exist in the films.…”

Section: X-ray Diffraction Ofmentioning

confidence: 99%

Melting Temperature of Thermally Reversible Gel. V. Heat of Fusion of Cellulose Triacetate and the Melting of Cellulose Diacetate–Benzyl Alcohol Gel

Takahashi

Kawaharada

Kato

1979

Polym J

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ABSTRACT:The heat of fusion of cellulose triacetate was determined from the melting point depression to be 2360cal mol-1 (9.87 kJ mol-1 ). The melting temperatures of thermally reversible gels of cellulose acetate in benzyl alcohol were measured over a range of polymer concentrations. The reciprocal of the gel melting temperature vs. In v2xw plot is linear, where v2 is the polymer volume fraction in the gel and xw is the weight-average degree of polymerization. The plot was analysed according to the thermodynamic theory of the melting of a gel and the crosslinking loci in the gel were inferred to be crystallites consist of triacetyl glucose units.KEY WORDS Cellulose Triacetate I Cellulose Diacetate I Acetyl Cellulose I Heat of Fusion I Gel I Sol-Gel Transition IThe sol-gel transition of secondary cellulose acetate has been receiving attention. The supramolecular structure of cellulose acetate gel is important for understanding the properties of cellulose acetate films prepared by the solvent cast and evaporation method, since the films are technically important for reverse osmosis. The thermally reversible gel formation of cellulose acetate in benzyl alcohol has been studied by several authors. 1 • 2 Recently, Goebel and Berry 3 investigated the supramolecular structure of the gel by light scattering and elasticity measurements. They concluded that the nonrandom character of the cross linking loci in the gel causes the smallangle light scattering. Furthermore, they estimated that the equivalent diameter D of the cross linking loci was 147 A from low-angle X-ray scattering and the formation of the cross linking loci was attributed to the three dimensional nucleation process. However, the length of the crystallite could not be estimated.In preceding papers of this series, one (AT) of the authors developed a thermodynamic theory for the melting of thermally reversible gels, assuming that cross linking locus is the crystallite of length ( units. 4 Despite that the melting point of gel is not the thermodynamic singularity, 4 according to this theory, the melting temperature of the gel (Tmg) is given by (1) In this equation, !1h 0 is the heat of fusion per crystalline monomer unit, Tm 0 is the melting temperature of pure polymer, (Jec is the end interfacial free energy of the crystallite, B' is the cohesive energy density of interaction between the crystalline unit A and the solvent medium which consists of a diluent and noncrystalline units, VA, V 1 are the molar volumes of the crystalline unit and the solvent, respectively, v 2 is the volume fraction of the polymer in the gel, X A is the mole fraction of crystalline unit and xw is the weight-average degree of polymerization. Equation 1 has been applied to evaluate the crystalline length (and interfacial free energy (Jec for many thermally reversible gels and ( thus evaluated compared favorably with (values estimated by other methods such as spectroscopy, elasticity and swelling of gels. 5 • 6 • 7 671

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Properties of cellulose acetate in solution. I. Light scattering, osmometry, and viscometry on dilute solutions

Cited by 77 publications

References 37 publications

Local Conformation of the Cellulosic Chain in Solution

Local Conformation of the Cellulosic Chain in Solution

Light Scattering, Classical: Size and Size Distribution Characterization

Melting Temperature of Thermally Reversible Gel. V. Heat of Fusion of Cellulose Triacetate and the Melting of Cellulose Diacetate–Benzyl Alcohol Gel

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