67 research outputs found
Textile Dyeing Using Nanocellulosic Fibers
Disclosed are various embodiments for dyeing a material using a dyed nanocellulose dispersion, thereby reducing or eliminating the need for water in dyeing materials, such as fabrics and textiles. A dyed nanocellulose dispersion or gel may be prepared from wood pulp fibers using a homogenizer and a dye, wherein the dyed nanocellulose dispersion comprises nanosized cellulose fibrils. The dyed nanocellulose gel may comprise an approximate concentration of 0.5% to 6%. The dyed nanocellulose dispersion may be applied to a material, such as a fabric or textile material. The fabric or textile material can be dried resulting in a dyed material
Oberflächen passen sich an - bürstenartige Polymermoleküle an Oberflächen mit schaltbaren Eigenschaften
It is the surface which in many cases determines the appearance and application-relevant properties of a material. Thin films of polymer brushes just a few nanometres in thickness can change the surface properties significantly and may provide even switching capabilities, where the thin film will for instance take up or repel water. Polymer brushes of two largely different polymer materials must in this case be tightly attached at one end to a solid substrate and will then occupy alternatively the upper or lower surface layer, depending on external conditions. In this way, either one or the other polymer material will be exposed and influence the surface properties. This purely physical switching process can be controlled by external triggers (selective or non-selective solvents, pH value, temperature, etc.). The physico- chemical surface properties (wettability, functionality etc.) switch between values established by the properties of the polymer materials involved.Oberflächen bestimmen in vielen Fällen das Erscheinungsbild und wichtige Gebrauchseigenschaften von Materialen. Bereits wenige Nanometer dünne Polymerfilme können diese Eigenschaften signifikant verändern und erlauben es, diese Eigenschaften sogar zu schalten, sodass ein Film beispielsweise Wasser abweisen oder aufnehmen kann. Hierzu werden Polymerbürsten aus zwei sehr verschiedenen Polymeren mit dem einen Ende fest an ein Substrat gebunden. In Abhängigkeit von den äußeren Bedingungen können sie sich dann wechselseitig an der Oberfläche anreichern, sodass die Oberflächeneigenschaften jeweils durch das eine oder andere Polymer bestimmt werden. Dieser rein physikalische Schaltprozess kann durch externe Stimuli (selektive oder nichtselektive Lösungsmittel, pH-Wert, Temperatur etc.) initiiert werden, wobei die physiko-chemischen Oberflächeneigenschaften (Benetzbarkeit, Funktionalität etc.) zwischen den durch die Eigenschaften der verwendeten Polymere bestimmten Extremwerten hin und her schalten können
Mixed Polymer Brushes with Locking Switching
Mixed polymer brushes, made of two different kinds of
polymers
randomly grafted to the same solid substrate, were introduced as switchable
interfaces for a number of promising applications. The switching properties
of the mixed polymer brushes are substantially dependent on grafting
density, molecular weight, compatibility of two distinct grafted polymers,
and their interaction with the solvent. This work reports the mixed
polymer brushes with the property of locking switching. The wetting
properties of such a mixed brush can be switched between the wetting
properties of individual constituting polymers by appropriate selection
of solvent. However, the mixed polymer brushes wetting behavior can
be locked in the hydrophobic state. This kinetically frozen methastable
state, however, can be unlocked via treatment by proper “unlocking”
solvent. This locking and unlocking of the hydrophobic state of the
mixed brush with specific solvents could find useful applications
for the development of functional materials
Nanopatterning of Solvent between Apposing Planar Brushes under Pressure
Using computer simulation of a coarse-grained, bead–spring model as well as scanning-probe microscopy of polytBA brushes in ethanol, we demonstrate that upon compression a poor solvent between two apposing polymer brushes does not remain a uniform thin film but, instead, forms a lateral, nanoscopic structure. The characteristic lateral length scale of the solvent domains scales with the brush height that, in turn, can be controlled by the grafting density, molecular weight, or pressure. These findings are rationalized in terms of geometric considerations, accounting for the interfacial free energy between the solvent and the brush and the spatial arrangement of the grafted chains. The phenomenon offers a general strategy to laterally structure confined fluids.Fil: Pastorino, Claudio. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentina. ComisiĂłn Nacional de EnergĂa AtĂłmica; ArgentinaFil: Kim, Yongwook. University of Georgia; Estados UnidosFil: Minko, Sergiy. University of Georgia; Estados UnidosFil: MĂĽller, Marcus. Universität Göttingen; Alemani
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