Adjustment of Hydrophobic Properties of Cellulose Materials

Abstract

In this study, physicochemical and chemical methods of cellulose modification were used to increase the hydrophobicity of this natural semicrystalline biopolymer. It has been shown that acid hydrolysis of the initial cellulose increases its crystallinity, which improves hydrophobicity, but only to a small extent. A more significant hydrophobization effect was observed after chemical modification by esterification, when polar hydroxyl groups of cellulose were replaced by non-polar substituents. The esterification process was accompanied by the disruption of the crystalline structure of cellulose and its transformation into the mesomorphous structure of cellulose esters. It was found that the replacement of cellulose hydroxyls with ester groups leads to a significant increase in the hydrophobicity of the resulting polymer. Moreover, the increase of the number of non-polar groups in the ester substituent contributes to rise in hydrophobicity of cellulose derivative. Depending on the type of ester group, the hydrophobicity increased in the following order: acetate < propionate < butyrate. Therefore, tributyrate cellulose (TBC) demonstrated the most hydrophobicity among all studied samples. In addition, the mixed ester, triacetobutyrate cellulose (TAB), also showed a sufficiently high hydrophobicity. The promising performance properties of hydrophobic cellulose esters, TBC and TAB, were also demonstrated.

Preparation of Transparent Fast-Growing Poplar Veneers with a Superior Optical Performance, Excellent Mechanical Properties, and Thermal Insulation by Acetylation Modification Using a Green Catalyst

“…As a hydrophobic group, the substitute of acetyl group would reduce the binding force of hydrogen bonds between celluloses and space out the cellulose fibers; accordingly, the fiber bulges and micropores appeared on the cross-sections of the cell wall [20], and this phenomenon became more distinctness with the increase of acetylation time. On the other hand, the contact angle test indicates that the initial contact angle of DPV was 0 • due to its hydrophilia [21]; however, the initial contact angles for ADPV-1, -3, and -5 were gradually increased, and were 45 • , 54 • , and 59 • , respectively; at the same time, the moisture absorption of all ADPVs are also evaluated, as shown in Figure 2f. The moisture absorption was gradually increased with the relative moisture varied from 25% to 100% for all specimens, noting that all ADPVs still displayed a lower moisture absorption than DPV, and the moisture absorption of ADPVs decreased with the increase in acetylation time.…”

Study of water vapor sorption by cellulose esters with different degrees of substitution

“…The esterification of the original cotton cellulose was carried out in the medium of trifluoroacetic acid (TFAA) served as a solvent and also a catalyst [6]. Cotton cellulose was mixed with TFAA while stirring at room temperature for 1 h and then treated with anhydrides of various aliphatic acids at 323 K for 1 h using a liquid to cellulose ratio of 50.…”

“…Currently, various cellulose esters, such as acetates, propionates, butyrates, and others are applied in the production of packaging materials, thermoplastics, eyeglass frames, cigarette filters, semi-permeable and separating membranes, optical films, water-and rot-resistant fabrics, self-cleaning materials, protective coatings, etc. [3][4][5][6].…”

Preparation, Characterization and Application of Amorphized Cellulose—A Review

“…Corrections include the coefficient of X-ray absorption, LP coefficient, and Rietveld refinement. Corrected diffraction patterns are used to determine various structural characteristics of cellulose samples [22][23][24].…”