1,721,359 research outputs found
Polydopamine and Cellulose: Two Biomaterials with Excellent Compatibility and Applicability
No full textIn recent decades, the role of poly(dopamine) in governing mussel adhesion has been gradually understood and exploited as a novel bio-mimicking adhesion concept. In parallel, the polysaccharide materials present a broad class of functional materials ranging from macro- to nanoscale components with broad variety in chemical structure, morphology and reactivity. The cross-over between both research fields enables the creation of fascinating materials with advanced engineering properties, where the (poly)dopamine serves as a general platform for the functionalization of polysaccharides. In this review, the role of poly(dopamine) in modification of cellulose and nanocellulose materials is discussed by means of several recent examples from literature. A broad variety of applications is presented, including bio-composites, nanoparticles and nanofibers, nanocomposites, hydrogels, aerogels, textiles, adhesives, films and papermaking applications. The review aims at stressing the viability of technical applications against a background of both the chemical and engineering aspects of dopamine-modified cellulose.Samyn, P (corresponding author), Hasselt Univ, Inst Mat Res Appl & Analyt Chem, Agoralaan Gebouw D, B-3590 Diepenbeek, Belgium.
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Engineering the Cellulose Fiber Interface in a Polymer Composite by Mussel-Inspired Adhesive Nanoparticles with Intrinsic Stress-Sensitive Responsivity
No full textThe interface between the fiber and matrix plays a key role in polymer composite performance and is adapted by chemical modification of the fiber surface. In this study, biomimetic adhesive nanoparticles formed by the self-assembly of polymer-peptide amphiphiles with a polydiacetelyene tail and local presentation of 3-hydroxyphenylalanine or DOPA adhesive groups at the outer surface are adsorbed on cellulose fiber surfaces for (i) probing the nanoscale adhesion in combination with a functionalized atomic force microscopy tip and (ii) evaluating the macroscale adhesion by single-fiber pull out tests from a solvent cast cellulose/poly(methyl methacrylate) composite. The interface properties are altered by changing the structure of the nanoparticles into either vesicular or planar shapes depending on the number of incorporated amphiphiles with adhesive groups and the nanoparticle concentration at the cellulose fiber surface. Based on nanoscale adhesive measurements, the adhesion force on modified cellulose fibers increases as a function of the nanoparticle concentration and is higher for the vesicular than for the planar nanoparticle structures. However, the local presentation and number of adhesive groups seems to rule over the surface roughness effects. From macrosale tests, an optimum concentration of adhesive vesicles provides maximum interface strength, while the formation of nanoparticle multilayers at higher concentrations results in lower interface adhesion. In addition, the intrinsic fluorescent properties of the adhesive vesicles under mechanical stress provide a unique tool to evaluate local failure and stress concentrations in the fiber/matrix interface. The incorporation of both adhesive and sensitive properties and versatility of the adhesive functional group may be an attractive strategy for the surface modification of fiber-reinforced composites in general.Funding for this research was provided by the Robert Bosch Foundation (Germany, Stuttgart) in the framework of the junior professorship program on research into sustainable use of natural resources, project "Foresnab-Sustainable use of forest resources as nanoscale building blocks for functional bio-composites and devices". The TEM measurements were kindly supplied by Dr. Ralph Thomann. The access to AFM and mechanical testing was facilitated by the Freiburg Materials Research Center.Samyn, P (corresponding author), Hasselt Univ, Inst Mat Res Appl & Analyt Chem, B-3590 Diepenbeek, Belgium.
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Plasma-assisted fibrillation and surface-modification of microfibrillar cellulose
No full textThe combination of microcrystalline cellulose (MCC) with maleic anhydride (MA) allowed for in-situ fibrillation and surface modification during pulsed plasma polymerization. Under optimized plasma parameters, the microfibrillated cellulose (MFC) morphology could be tuned according to the positioning in the reactor from small and short fibrils towards more elongated and crystallite structures in relation to the complex interactions between activated species. The chemical surface esterification was verified and resulted in good dispersion and higher water contact angle of the fibrils. The proposed route is an attractive 'green' and low-energy alternative for traditional mechanical processing and modification of nanocelluloses
Engineered nanomaterials for papermaking industry
No full textThe interest in nanomaterials for papermaking industry has strongly increased in the latest decade in order to improve the properties of existing paper products or create new functionalities to papers. In this chapter, a broad overview of nanomaterials derived from paper products or nanofillers used during papermaking is given. The recent advances in producing nanocellulose as microfibrillated cellulose or cellulose nanowhiskers are discussed, together with the preparation routes for a range of inorganic and organic nanofillers. The electrospinning of paper constituents is an alternative way for the creation of nanostructured materials. Some novel trends include the in-situ modification of nanofibers and nanofillers in order to tune their surface properties. However, most prominent challenges remain associated with the definition of suitable processing conditions, which are evaluated in terms of rheology and retention properties of nanomaterials. The benefits of nanofillers and nanopigments to create several functionalities to the paper bulk or surface are shortly discussed
Active coating for packaging papers with controlled thermal release of encapsulated plant oils
No full textThe surface properties and water repellence of paper substrates can be tuned by a waterborne nanoparticle coating containing hybrid organic nanoparticles with encapsulated vegetable oils. In particular, the release of oil from the deposited nanoparticle capsules can be activated upon thermal heating. The specific release tempera-ture allows to control the amount of free oil at the surface and consequent tuning of required hydrophobicity. This study particularly focusses on a detailed monitoring of variations in chemical surface composition upon controlled oil release by means of micro-Raman mapping. The coverage of surfaces with both free oil and imide moieties originating from the organic nanoparticles can be quantified after a calibration between Raman spectra and extraction studies of the nanoparticles. As such, different thermal release profiles were observed depending on the type of encapsulated oils, i.e. polyunsaturated oil (e.g., soy oil, corn oil), mono-unsaturated oil (e.g., rapeseed oil, castor oil), or saturated oil (e.g., hydrogenated castor oil). The oil release can interestingly be related to variations in surface chemistry and water contact angles, as it seems that the surface hydrophobicity increases with the chemical heterogeneity that is quantified by oil content, imide content and iodine value of the oil
Active Barrier Coating for Packaging Paper with Controlled Release of Sunflower Oils
No full textThe use of paper as a sustainable packaging material is favored, but it lacks sufficient barrier properties in terms of water repellence and oil resistance. Novel approaches consider active packaging materials or coatings with controlled release providing additional functionality for delivery of specific components to the surface. In this study, the development of a waterborne coating with organic nanoparticles and encapsulated sunflower oils is presented as a system for thermal release of the oil and on-demand tuning of the final barrier properties of the paper substrate. After synthesis of the nanoparticles, it seems that the encapsulation of various grades of sunflower oil (i.e., either poly-unsaturated or mono-unsaturated) strongly affects the encapsulation efficiency and thermal release profiles. The water contact angles are controlled by the oil release and chemical surface composition of the coating upon thermal heating. The oil resistance of the paper improves as a more continuous oil film is formed during thermal release. In particular, the chemical surface composition of the paper coatings is detailed by means of micro-Raman spectroscopy and surface imaging, which provide an analytical quantification tool to evaluate surface coverage, oil delivery, and variations in organic coating moieties
Engineered nanomaterials for papermaking industry
No full textThe interest in nanomaterials for papermaking industry has strongly increased in the latest decade in order to improve the properties of existing paper products or create new functionalities to papers. In this chapter, a broad overview of nanomaterials derived from paper products or nanofillers used during papermaking is given. The recent advances in producing nanocellulose as microfibrillated cellulose or cellulose nanowhiskers are discussed, together with the preparation routes for a range of inorganic and organic nanofillers. The electrospinning of paper constituents is an alternative way for the creation of nanostructured materials. Some novel trends include the in-situ modification of nanofibers and nanofillers in order to tune their surface properties. However, most prominent challenges remain associated with the definition of suitable processing conditions, which are evaluated in terms of rheology and retention properties of nanomaterials. The benefits of nanofillers and nanopigments to create several functionalities to the paper bulk or surface are shortly discussed
Biomimetic adhesive interlayers for technological applications with intrinsic stress-sensitive respons
No full textImpressive adhesive mechanisms are encountered in nature, such as the sticking properties of mussels onto various surfaces mediated by a series of mussel-foot proteins containing dihydroxyphenylalanine (DOPA). In order to better exploit the bio-based adhesive functions in technical applications such as microsystem components, sensor devices and biopolymer composites, a synthetic route has been developed for coupling of a specific adhesive peptide with a lipid diacetylenic tail and self-organization into nanoscale vesicles that were stabilized by UV-induced polymerization. Adhesive micro-arrays were made onto patterned substrates by means of a lithographic methods and subsequent confinement of the aqueous vesicle solution onto hydrophilic spots. Alternatively, the vesicles may be adsorbed onto cellulosic fibers in order to control the interface properties after incorporation into polymer composites. The colorimetric and fluorescent responses of the interfaces are probed as a function of interfacial stress
Biomimetic adhesive interlayers for technological applications with intrinsic stress-sensitive respons
No full textImpressive adhesive mechanisms are encountered in nature, such as the sticking properties of mussels onto various surfaces mediated by a series of mussel-foot proteins containing dihydroxyphenylalanine (DOPA). In order to better exploit the bio-based adhesive functions in technical applications such as microsystem components, sensor devices and biopolymer composites, a synthetic route has been developed for coupling of a specific adhesive peptide with a lipid diacetylenic tail and self-organization into nanoscale vesicles that were stabilized by UV-induced polymerization. Adhesive micro-arrays were made onto patterned substrates by means of a lithographic methods and subsequent confinement of the aqueous vesicle solution onto hydrophilic spots. Alternatively, the vesicles may be adsorbed onto cellulosic fibers in order to control the interface properties after incorporation into polymer composites. The colorimetric and fluorescent responses of the interfaces are probed as a function of interfacial stress
Melt-Processing of Biopolymer Composites with Nanocellulose Additives
No full textCellulose fibers are advantageous reinforcing materials for biobased composites because of their availability and good mechanical properties. Several chemical processes have been developed to turn the native fibers into micro- (MFC) or nanofibrillated (NFC) cellulose fibers. These nanocomponents are believed to even have stronger reinforcing capacity because of surface interaction effects at the nanoscale and formation of a fine web structure. During further processing of fibrillated cellulose in combination with a biopolymer matrix, however, there is evidence of agglomeration due to the hydrophilic nature of the fibers and incompatibility with the polymer matrix. In our approach, surface modification of the micro- and nanofibrillated cellulose is done by the in-situ deposition of hydrophobic nanoparticles onto the fiber surface, allowing to tune the required hydrophobicity of the cellulose additives and to make them compatible with extrusion applications, as demonstrated for PLA biopolymers.RWTH Aachen Univ, Inst Plast Proc Ind & Craf
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