Hydrophobicity improvement of cellulose nanofibrils films by stearic acid and modified precipitated calcium carbonate coating

Abstract

The development of a cellulose nanofibrils film with permanent hydrophobicity using green processes, avoiding hazardous solvents, through easy procedures, is a great challenge. The hydrophobicity of a layer of calcium carbonate modified with stearic acid has already been presented. However, the combination of a cellulose nanofibrils film with a layer of modified calcium carbonate to develop a permanent hydrophobic cellulose-based material rises the additional issue of adhesion between layers. In the present study, a set of cellulose nanofibrils films was coated with a layer of stearic acid and another set was additionally covered with modified precipitated calcium carbonate (0.4–6 µm sized particles with above 50% aragonite crystalline form), previously modified with a stearic acid suspension using ultrasounds. To investigate the issue of adhesion between layers, some films were subjected to heat treatments at 68 and 105 °C. Structural and physical analysis of the films, as well as barrier properties and static/dynamic contact angle measurements were performed. Results show that overall mechanical performance of the films was not substantially affected by the coating and posterior heat treatments. Heat treatments decreased the water vapor transmission rate of stearic acid coated films from 91.9 to 31.6 g m−2 day−1 and the oxygen permeability of stearic acid and modified calcium carbonate coated films from 26.4 to 2.6 cm3 µm/(m2 day kPa). The double layered coated cellulose nanofibrils films attained contact angle hysteresis of 3.1° and 5° and static contact angles of 150° and 140° with no heat treatment and with a heat treatment of 68 °C, respectively. The heat treatment enabled to permanently adhere modified calcium carbonate particles on the film, providing it with persistent hydrophobicity.

Assessment of two in‐situ and ex‐situ methods for silver/graphene oxide‐grafted cotton fabrics fabrication and antibacterial activity enhancement by hydrophobic modification with stearic acid

“…The partial washout of the covered SA layer is believed to be the main cause of the lowering of the WCA value. Nonetheless, after washing test cycles, the WCA values are almost unchanged, indicating the great effectiveness and potential of the SA fatty acid modification to enhance the hydrophobicity as compared to previous methods such as the direct reduction of GO to rGO through chemical treatment, hydrophobic modification by precipitating calcium carbonate, and so forth 15,34 …”

“…However, the second routine of the linkage mechanism is not feasible due to the lack of catalysts and temperature as motivating factors. Alternatively, the pathway of esterification, as well, is partially hindered which can be attributed to the occurrence of the hydrolysis reaction as a reversible reaction of the esterification reaction 34,38 . Thus, it supposes to be the first mechanism way is more possible due to the orderly structure arrangement between the long‐chain tails and silver ions existing on the surface of AgNPs.…”

“…Nonetheless, after washing test cycles, the WCA values are almost unchanged, indicating the great effectiveness and potential of the SA fatty acid modification to enhance the hydrophobicity as compared to previous methods such as the direct reduction of GO to rGO through chemical treatment, hydrophobic modification by precipitating calcium carbonate, and so forth. 15,34 3.8 | Linkage formation and antibacterial mechanism of Ag/GO/cotton fabrics Interestingly, the fabrication of the antibacterial cotton fabrics is accomplished through the coating and adhesion of Ag/GO suspension onto the fabric surface. This adhesion is mainly formed through hydrogen bonding between the hydroxyl groups of GO and the cellulose fiber systems present in the fabric, along with the additive synergism of electrostatic interactions and weak van der Waals forces (Figure 17).…”

Preliminary Study on the Preparation of Conductive Nanosized Calcium Carbonate Utilizing Biogas Slurry by a Synchronous Double Decomposition Coating Method

“…It is understood that most CNCC composite conductive powders are prepared by using NCC products coated with inorganic or organic conductive materials as a template [ 39 , 42 , 46 ]. This preparation of CNCC is called the asynchronous method.…”

One pot application of a green chemistry-based finish for cotton fabric, providing hydrophobic, flame retardant, and antimicrobial properties

“…Notably, the WCAs for samples treated with 8% nishing approximately approach the benchmark for super hydrophobicity, set at 150 degrees. 56 However, cotton fabric treated with 12% of the nishing agents exhibits a water contact angle slightly higher than the benchmark.…”