Investigation of cellulose nanocrystals (CNC) and cellulose nanofibers (CNF) as thermal barrier and strengthening agents in pigment-based paper coatings

Hydrogels have been studied as promising materials in different biomedical applications such as cell culture in tissue engineering or in wound healing. In this work, we synthesized different nanocellulose-alginate hydrogels containing cellulose nanocrystals, TEMPO-oxidized cellulose nanocrystals (CNCTs), cellulose nanofibers or TEMPO-oxidized cellulose nanofibers (CNFTs). The hydrogels were freeze-dried and named as gels. The nanocelluloses and the gels were characterized by different techniques such as Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and dynamic mechanical thermal analysis (DMTA), while the biological features were characterized by cytotoxicity and cell growth assays. The addition of CNCTs or CNFTs in alginate gels contributed to the formation of porous structure (diameter of pores in the range between 40 and 150 μm). TEMPO-oxidized cellulose nanofibers have proven to play a crucial role in improving the dimensional stability of the samples when compared to the pure alginate gels, mainly after a thermal post-treatment of these gels containing 50 wt % of CNFT, which significantly increased the Ca2+ crosslinking density in the gel structure. The morphological characteristics, the mechanical properties, and the non-cytotoxic behavior of the CNFT-alginate gels improved bioadhesion, growth, and proliferation of the cells onto the gels. Thus, the alginate-nanocellulose gels might find applications in tissue engineering field, as for instance, in tissue repair or wound healing applications.

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Three-dimensional Hydrogels of Alginate/chitosan Semi-interpenetrating Polymer Networks and Nanocelluloses

10.21203/rs.3.rs-706130/v1 ◽

2021 ◽

Author(s):

Priscila Siqueira ◽

Ana de Lima ◽

Felipe Medeiros ◽

Augusta Isaac ◽

Katia Novack ◽

...

Keyword(s):

Mechanical Properties ◽

Dimensional Stability ◽

Cellulose Nanocrystals ◽

Biomedical Applications ◽

Cellulose Nanofibers ◽

Polymer Networks ◽

Three Dimensional ◽

Controlled Drug Release ◽

Interpenetrating Polymer Networks ◽

Post Treatment

Abstract The hydrogels are advanced materials used in biomedical applications during wound healing, controlled drug release and to prepare scaffolds. In this work are prepared hydrogels of alginate/chitosan (Alg/Ch) semi-interpenetrating polymer networks (semi-IPN’s) and nanocelluloses. The hydrogels after preparation by freeze drying are namely simply as gels. The cellulose nanocrystals (CNC’s) are obtained from acid hydrolysis of bleached Eucalyptus pulps and oxidized cellulose nanocrystals (CNCT’s) prepared by (2,2,6,6-tetramethylpiperidin-1-yl)oxyl radical catalyzed reaction as known as TEMPO reaction. The cellulose nanofibers (NFC’s) are obtained from mechanical shearing of cellulose pulps and oxidized NFC’s by TEMPO-mediated reaction (NFCT’s). The nanocellulose suspension and gels are characterized by FTIR at ATR mode, TGA, XRD, TEM, SEM, X-ray computed microtomography (micro-CT) and DMTA. The addition of CNC’s, NFC’s, CNCT’s or NFCT’s in the microstructure of gels increases their dimensional stabilities. The best results are obtained when CNCT’s and NFCT’s are added. The mechanical properties and dimensional stability of Alg/Ch semi-IPN’s increase after controlled thermal post-treatment. The heating during thermal post-treatment boosts the physicochemical interactions in the microstructures of semi-IPN’s. The biological assays show biocompatibility of fibroblast cells on the substrates, and differentiation and proliferation up seven days. The optimized mechanical properties, dimensional stability and biocompatibility of the gels studied in this work are important parameters for potential biomedical applications of these biomaterials.

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Preparation and Comparative Study of Aerogels Based on Cellulose Nanocrystals and Nanofibers from Eucalyptus Pulp

10.21203/rs.3.rs-1005528/v1 ◽

2021 ◽

Author(s):

Wenkai Zhu ◽

Yang Zhang ◽

Xiaoyu Wang ◽

Yan Wu ◽

Minsu Han ◽

...

Keyword(s):

Cellulose Nanocrystals ◽

Chemical Structure ◽

Sol Gel ◽

Cellulose Nanofibers ◽

Mesoporous Structure ◽

Drying Process ◽

Biophysical Properties ◽

Eucalyptus Pulp ◽

Mechanical Methods ◽

Significant Attention

Abstract Nanocellulose-based materials have attracted significant attention because of their attractive advantages. Particularly, aerogel, a porous nanocellulose material, have been used in diverse applications owing to their unique properties. In this study, short rod-like cellulose nanocrystals (CNCs) and long filament-like cellulose nanofibers (CNFs) were isolated from a eucalyptus pulp source using acidolysis and oxidation/mechanical methods, respectively. Subsequently, two different aerogels were prepared from the CNCs and CNFs using the sol-gel method and their properties were compared. The morphology, chemical structure, chemical composition, shrinkage rate, internal structure, thermal degradation, biophysical properties, and mechanical properties of the as-prepared aerogels were compared. Furthermore, the shrinkage of the CNC and CNF aerogels was effectively controlled using a supercritical CO2 drying process. Additionally, three decomposition regions were observed in the thermogravimetric analysis curves of the aerogels; however, the CNF aerogels exhibited enhanced thermal stability than the CNC aerogels. Further, the CNC and CNF aerogels exhibited a mesoporous structure, and the compressive strength of the CNC and CNF aerogels under 85% strain was 269.5 and 299.5 KPa, respectively. This study provides fundamental knowledge on the fabrication of CNCs, CNFs, and corresponding aerogels from lignocellulosic biomass, and their characteristics.

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Adsorption of biopolymers onto nanocelluloses for the fabrication of hollow microcapsules

Nordic Pulp & Paper Research Journal ◽

10.1515/npprj-2021-0040 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Salvatore Lombardo ◽

Bernard Cathala ◽

Ana Villares

Keyword(s):

Quartz Crystal Microbalance ◽

Cellulose Nanocrystals ◽

Quartz Crystal ◽

Cellulose Nanofibers ◽

Aqueous Media ◽

Three Dimensional ◽

Functional Materials ◽

Crystalline Cellulose ◽

Multilayer Adsorption ◽

Adsorbed Polymer

Abstract In this work, we studied the multilayer adsorption of cellulose nanocrystals and cellulose nanofibers with other polysaccharides such as xyloglucan and chitosan. We showed that the specific interactions between these biopolymers can be exploited to prepare three-dimensional functional materials. Quartz crystal microbalance studies showed that both biopolymers were adsorbed irreversibly on the nanocellulose surfaces. In aqueous media, the maximum amount of adsorbed polymer was higher for the smaller and more crystalline cellulose nanocrystals, compared to cellulose nanofibers. For both nanocelluloses employed, the amount of xyloglucan of the first bilayer was larger than the amount of chitosan adsorbed. Ellipsometry showed that both xyloglucan and chitosan were adsorbed on nanocellulose surfaces. However, at the second layer no mass change was detected by quartz crystal microbalance when xyloglucan was added, while for addition of successive layers of chitosan a decrease of frequency was detected. The water uptake of multilayers was higher for cellulose nanocrystals than for nanofibers, which was ascribed the presence of voids in the nanocrystal layer. Finally, we demonstrated that multilayer adsorption of these biopolymers can be performed on calcium carbonate sacrificial templates, which can then be removed to yield hollow polysaccharide microcapsules.

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Pretreatment assisted synthesis and characterization of cellulose nanocrystals and cellulose nanofibers from absorbent cotton

International Journal of Biological Macromolecules ◽

10.1016/j.ijbiomac.2017.03.172 ◽

2017 ◽

Vol 102 ◽

pp. 248-257 ◽

Cited By ~ 24

Author(s):

Emmanuel Abu-Danso ◽

Varsha Srivastava ◽

Mika Sillanpää ◽

Amit Bhatnagar

Keyword(s):

Cellulose Nanocrystals ◽

Cellulose Nanofibers ◽

Synthesis And Characterization ◽

Absorbent Cotton

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Cellulose nanofiber-assisted dispersion of cellulose nanocrystals@polyaniline in water and its conductive films

RSC Advances ◽

10.1039/c5ra19346j ◽

2016 ◽

Vol 6 (12) ◽

pp. 10168-10174 ◽

Cited By ~ 16

Author(s):

Shiqi Wang ◽

Chun Wei ◽

Yongyang Gong ◽

Jian Lv ◽

Chuanbai Yu ◽

...

Keyword(s):

Electrical Conductivity ◽

Cellulose Nanocrystals ◽

Cellulose Nanofibers ◽

Environmentally Friendly ◽

Cellulose Nanofiber ◽

High Electrical Conductivity ◽

Conductive Films

The cellulose nanofibers as an efficient and environmentally friendly dispersant have been proven to be an efficient way to disperse cellulose nanocrystals@polyaniline. The obtained film show high electrical conductivity.

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Effects of Cellulose Nanocrystals and Cellulose Nanofibers on the Structure and Properties of Polyhydroxybutyrate Nanocomposites

Polymers ◽

10.3390/polym11122063 ◽

2019 ◽

Vol 11 (12) ◽

pp. 2063 ◽

Cited By ~ 7

Author(s):

Bobo Zhang ◽

Chongxing Huang ◽

Hui Zhao ◽

Jian Wang ◽

Cheng Yin ◽

...

Keyword(s):

Cellulose Nanocrystals ◽

Cellulose Nanofibers ◽

Simple Approach ◽

Nucleating Agents ◽

Structure And Properties ◽

Thermal And Mechanical Properties ◽

Elongation At Break ◽

Biocompatible Polymer ◽

Commercial Applications ◽

Toughening Modification

One of the major obstacles for polyhydroxybutyrate (PHB), a biodegradable and biocompatible polymer, in commercial applications is its poor elongation at break (~3%). In this study, the effects of nanocellulose contents and their types, including cellulose nanocrystals (CNCs) and cellulose nanofibers (CNFs) on the crystallization, thermal, and mechanical properties of PHB composites were systematically compared. We explored the toughening mechanisms of PHB by adding CNCs and cellulose CNFs. The results showed that when the morphology of bagasse nanocellulose was rod-like and its content was 1 wt %, the toughening modification of PHB was the best. Compared with pure PHB, the elongation at break and Young’s modulus increased by 91.2% and 18.4%, respectively. Cellulose nanocrystals worked as heterogeneous nucleating agents in PHB and hence reduced its crystallinity and consequently improved the toughness of PHB. This simple approach could potentially be explored as a strategy to extend the possible applications of this biopolymer in packaging fields.

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Novel all-cellulose composite displaying aligned cellulose nanofibers reinforced with cellulose nanocrystals

TAPPI Journal ◽

10.32964/tj10.4.19 ◽

2011 ◽

Vol 10 (4) ◽

pp. 19-25 ◽

Cited By ~ 9

Author(s):

WASHINGTON LUIZ ESTEVES MAGALHÃES ◽

XIAODONG CAO ◽

MAGALY ALEXANDRA RAMIRES ◽

LUCIAN A. LUCIA

Keyword(s):

Dimethyl Sulfoxide ◽

Cellulose Nanocrystals ◽

Cellulose Nanofibers ◽

Crystallinity Index ◽

Nanocomposite Films ◽

Amorphous Cellulose ◽

Fiber Mats ◽

Sem Image ◽

Pure Cellulose ◽

Nanocomposite Fibers

Aligned cellulose nanocrystals/cellulose coelectrospun nanofibers were successfully prepared by using a home-built coelectrospinning and collection system. Cellulose I was dissolved in N-methyl morpholine oxide at 120°C and diluted with dimethyl sulfoxide, which was used in the external concentric capillary needle as the sheath (shell) solution. A cellulose nanocrystal suspension obtained by sulfuric acid hydrolysis of cotton fibers was used as the core liquid in the internal concentric capillary needle after transferring from water to dimethyl sulfoxide. The resultant coelectrospun nanocomposite films were collected onto a rotating wire drum and were characterized by field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy, thermogravimetric analysis, and tensile measurements. The FE-SEM image showed that the cellulose nanocrystals did not appear to cluster in the film formed. Although the crystallinity index of nanocomposite fibers was lower than the unreinforced cellulose electrospun fibers, the cellulose type II reinforced with cellulose nanocrystals had a much higher tensile stress (about 140 MPa), almost twofold that of pure cellulose. This latter result indicated that the alignment and adhesion of amorphous cellulose nanofibers played a crucial role on the mechanical properties of electrospun cellulosic fiber mats.

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