Thermodynamic and Hydrodynamic Properties of Cellulose Diacetate–Dimethylacetamide Solutions

Abstract

ABSTRACT:Viscometric and light scattering investigations were carried out on cellulose diacetate (degree of substitution, DS = 2.46) in dimethylacetamide (DMAc) at 25cC. The following molecular weight dependence of limiting viscosity number [17] Cellulose acetate (CA) with different degrees of substitution (DS) constitute a series of polymers whose molecular properties have not been systematically explored, mainly because of the experimental difficulty in removing gel-like materials from the solutions. Consequently, the molecular characterization of CA has been a subject of considerable interest in our laboratory 1 -21 for the past ten years, and dilute solutions of this polymer have been extensively studied by light scattering, membrane osmometry, viscometry, gel-permeation chromatography, ultracentrifugation, thin-layer chromatography, and nuclear magnetic reasonance. 0-acetyl groups in CA and solvent molecules. (3) The extent of solvation is also correlated to solvent polarity.By these studies the characteristic features of CA solutions have been progressively made clear, especially with regard to the following points: (I) the unperturbed chain dimensions A of cellulose diacetate (CDA; CA with DS = 2.46) and CA with DS = 0.49 vary markedly depending on the kind of solvent, being larger in a solvent with larger polarity. (2) The variation in A with solvent is correlated closely to specific interactions between functional groups, such as the hydroxyl and the In the course of the above-mentioned studies, it was found that N,N'-dimethylacetamide (DMAc) is a solvent which readily dissolves the CA molecule with aDS ranging from 0.49 to 2.92. The systems of CA (DS=2.92) and CA (DS=0.49)/DMAc have been extensively studied in previous papers. 9 • 15 In this article, by investigating the dilute solution properties of CDA in DMAc and comparing with our previous data on this polymer in acetone and tetrahydrofuran (THF) 8 and on CA with different DS (2.92 9 and 0.49 15 ) in DMAc, we attempt to confirm the above-mentioned characteristic features (1)-(3) and reach a better understanding of the relationships between DS and the molecular properties of cellulose derivatives. EXPERIMENTAL PolymerFive cellulose diacetate fractions (DS = 2.46) pre-517

Mesophase formation and chain rigidity in cellulose and derivatives. 5. Cellulose acetate in N,N-dimethylacetamide

“…Dilute-solution data for CA in DMAc have been reported by Kamide et al11,12 These reveal no aggregation effects of the type observed for cellulose.3 However, association effects in relatively concentrated solutions have not been investigated.…”

Viscometric and Light Scattering Study on Dilute Solution Properties of Cellulose Acetate with a Degree of Substitution of 1.75

“…Here we used 0.504 X 10-8 (em) for Ar. 13 These values of a and C ro indicated that CA (DS= 1.75) is stiffer than CA (DS=0.49) and CA (DS=2.92), but more flexible than CA (DS = 2.46), on making a comparison of all these polymers in DMAc. We found by NMR and ultrasonic interferometer measurements that solvation occurs in DMAc solutions of CA (DS=0.49), CA (DS=2.46), and CA (DS=2.92) and that this solvation contributes mainly to the chain rigidity of cellulose acetate in DMAcP Therefore, it may be concluded that the difference in equilibrium chain rigidity among CA with different DS is a reflection 252 of the difference in degree of solvation.…”

“…75. From its 13 C NMR spectra in deuterated dimethylsulfoxide (DMSO-d 6 ), the average probabilities that the hydroxyl groups attached to the C2 , C3 , and C6 atoms were substituted by the 0-acetyl groups, i.e., ! {,_f 6 'J; were estimated to be 0.45, 0.54, and 0.76, respectively.…”

Wormlike Chain Parameters of Cellulose and Cellulose Derivatives

“…Figure 8 shows the relation between and db for a CA (2.46) sample (EF3-15) in DMAc. 19 In the range dbz5 X lO-S em, is almost independent of db. As shown in Table I concluded that is insensitive to db.…”

“…The friction constant (w per unit length of the wormlike cylinder is assumed to be equal to (P per unit length of the pearl necklace chain, i.e., (19) Ullman 7 derived a relation between (wand [YJ] for the wormlike cylinder with a finite cross section (see Figure lc), i.e., (20) with (21) Here, Wi is the weight associated with variable xi in the Gaussian quadrature formulas; k is a hydrodynamic interaction parameter corresponding to the draining parameter X for the pearl necklace chain, and cp(xi, x) is a dimensionless quantity proportional to the torque of the hydrodynamic force acting on a point of the wormlike cylinder. The equations in the Appendix of ref 7 12 hydroxyethyl cellulose (HEC) (l)jwater, 29 ethyl hydroxyethyl cellulose (EHEC)/water, 30 sodium carboxymethyl cellulose (NaCMC) (0.88)/aq NaCl (at the limit of infinite ionic strength, i.e., /-HY:J).…”