Trimethylsilyl Cellulose Research Articles

How Bound and Free Fatty Acids in Cellulose Films Impact Nonspecific Protein Adsorption.

The effect of fatty acids and fatty acid esters to impair nonspecific protein adsorption on cellulose thin films is investigated. Thin films are prepared by blending trimethylsilyl cellulose solutions with either cellulose stearoyl ester or stearic acid at various ratios. After film formation by spin coating, the trimethylsilyl cellulose fraction of the films is converted to cellulose by exposure to HCl vapors. The morphologies and surface roughness of the blends were examined by atomic force microscopy revealing different feature shapes and sizes depending on the blend ratios. Nonspecific protein adsorption at the example of bovine serum albumin toward the blend thin films was tested by means of surface plasmon resonance spectroscopy in real-time. Incorporation of stearic acid into the cellulose leads to highly protein repellent surfaces regardless of the amount added. The stearic acid acts as a sacrificial compound that builds a complex with bovine serum albumin thereby inhibiting protein adsorption. For the blends where stearoyl ester is added to the cellulose films, the cellulose:cellulose stearoyl ester ratios of 3:1 and 1:1 lead to much lower nonspecific protein adsorption compared to pure cellulose, whereas for the other ratios, adsorption increases. Supplementary results were obtained from atomic force microscopy experiments performed in liquid during exposure to protein solution and surface free energy determinations.

Modification of cellulose thin films with lysine moieties: a promising approach to achieve antifouling performance

Thin films of trimethylsilyl cellulose are obtained by spin coating and regenerated to cellulose. The surface is activated with N,N′-carbonyldiimidazole and aminolysis with lysine is carried out in aqueous solution to yield a cellulose lysine carbamate film. The surface is analytically characterized by ATR-IR spectroscopy, zetapotential measurements, contact angle measurements, and atomic force microscopy. The amount of functional groups is determined by pH potentiometric titration as well as the ninhydrin test and is in the range of 25 pmolcm−2. Adsorption of bovine serum albumine (BSA) and fibrinogen on the cellulose film and the cellulose lysine carbamate surface is studied at different pH values by quartz crystal microbalance with dissipation monitoring (QCM-D). The adsorption of BSA is significantly reduced by modification with lysine. At physiological pH value (7.4) the adsorption of fibrinogen is even six times lower (1.0 mgm−2) compared to the pure cellulose surface. Thus, cellulose thin films with lysine moieties are promising candidates for hemo-compatible antifouling surfaces in the field of blood contacting devices.

Interaction of industrially relevant cationic starches with cellulose

Industrially relevant, commercially available cationic starches have been investigated towards their interaction capacity with cellulose thin films derived from trimethylsilyl cellulose (TMSC). The starches used in this study stem from different sources (potato, pea, corn) and featured rather low degrees of substitution ranging from 0.030 to 0.062. The interaction of those starches with cellulose thin films was studied by surface plasmon resonance spectroscopy under flow conditions using concentrations of 1.0mgml−1 and a flow rate of 25μlmin−1. All the investigated starches employed in this study were capable to efficiently interact with the slightly negatively charged cellulose surface leading to irreversible deposition on the surface. As complementary techniques atomic force microscopy and x-ray photoelectron spectroscopy were used to confirm the presence of the starches on the cellulose film surface. Further, dynamic light scattering and size exclusion chromatography measurements were performed to correlate adsorbed amount, particle size and molecular weight of the starches to their interaction behavior.

Biobased Cellulosic–CuInS2 Nanocomposites for Optoelectronic Applications

A generic approach to design optoelectronic devices using renewable biopolymers is demonstrated. As a proof of principle, a biopolymer/CuInS2 nanocomponent-based solar cell has been assembled by using a cellulose derivative with a reasonable life cycle performance, namely, trimethylsilyl cellulose (TMSC). The solar cells are manufactured using a mixture of copper and indium xanthates as precursors, which decompose and form CIS nanoparticles within the biopolymer matrix during a thermal treatment, which was investigated by in situ combined grazing incidence small and wide-angle X-ray scattering experiments. The growth of the nanoparticles is thereby controlled by the TMSC matrix. The nanocrystals exhibit an average diameter of approximately 4 nm. Using this composite, it was possible to fabricate solar cells, generating current in a wide range of the solar spectrum and exhibiting power conversion efficiencies of ca. 1%.

On the formation of Bi2S3-cellulose nanocomposite films from bismuth xanthates and trimethylsilyl-cellulose

The synthesis and characterization of bismuth sulfide-cellulose nanocomposite thin films was explored. The films were prepared using organosoluble precursors, namely bismuth xanthates for Bi2S3 and trimethylsilyl cellulose (TMSC) for cellulose. Solutions of these precursors were spin coated onto solid substrates yielding homogeneous precursor films. Afterwards, a heating step under inert atmosphere led to the formation of thin nanocomposite films of bismuth sulfide nanoparticles within the TMSC matrix. In a second step, the silyl groups were cleaved off by vapors of HCl yielding bismuth sulfide/cellulose nanocomposite films. The thin films were characterized by a wide range of surface sensitive techniques such as atomic force microscopy, attenuated total reflection infrared spectroscopy, transmission electron microscopy and wettability investigations. In addition, the formation of the nanoparticle directly in the TMSC matrix was investigated in situ by GI-SWAXS using a temperature controlled sample stage.

Application of thin film cellulose composite membrane for dye wastewater reuse

The use of low cost membranes with high salt/dye selectivity and high flux is ideal for an economic and eco-friendly treatment of dye wastewater. Here, regenerated cellulose membranes prepared from trimethylsilyl cellulose are studied for treating artificial dye effluents. In the experiments using a feed containing Congo Red and high NaCl concentration, the membrane featured impressive dye removal with zero salt rejection combined with high flux. More interestingly, the membrane reached as much as 600 LMH flux at 80°C and 4bar while maintaining high dye rejection close to 98%. In prolonged experiments up to 75h the membrane exhibited good antifouling behavior with nearly 100% flux recovery. This study may provide a promising alternative of dye effluent treatment where high amounts of monovalent salts are present.

Direct-Write Fabrication of Cellulose Nano-Structures via Focused Electron Beam Induced Nanosynthesis.

In many areas of science and technology, patterned films and surfaces play a key role in engineering and development of advanced materials. Here, we introduce a new generic technique for the fabrication of polysaccharide nano-structures via focused electron beam induced conversion (FEBIC). For the proof of principle, organosoluble trimethylsilyl-cellulose (TMSC) thin films have been deposited by spin coating on SiO2 / Si and exposed to a nano-sized electron beam. It turns out that in the exposed areas an electron induced desilylation reaction takes place converting soluble TMSC to rather insoluble cellulose. After removal of the unexposed TMSC areas, structured cellulose patterns remain on the surface with FWHM line widths down to 70 nm. Systematic FEBIC parameter sweeps reveal a generally electron dose dependent behavior with three working regimes: incomplete conversion, ideal doses and over exposure. Direct (FT-IR) and indirect chemical analyses (enzymatic degradation) confirmed the cellulosic character of ideally converted areas. These investigations are complemented by a theoretical model which suggests a two-step reaction process by means of TMSC → cellulose and cellulose → non-cellulose material conversion in excellent agreement with experimental data. The extracted, individual reaction rates allowed the derivation of design rules for FEBIC parameters towards highest conversion efficiencies and highest lateral resolution.

Charge- and Size-Selective Molecular Separation using Ultrathin Cellulose Membranes.

To date, it is still a challenge to prepare high-flux and highselectivity microporous membranes thinner than 20 nm without introducing defects. In this work, we report for the first time the application of cellulose membranes for selective separation of small molecules. A freestanding cellulose membrane as thin as 10 nm has been prepared through regeneration of trimethylsilyl cellulose (TMSC). The freestanding membrane can be transferred to any desired substrate and shows a normalized flux as high as 700 L m-2 h-1 bar-1 when supported by a porous alumina disc. According to filtration experiments, the membrane exhibits precise size-sieving performances with an estimated pore size between 1.5-3.5 nm depending on the regeneration period and initial TMSC concentration. A perfect discrimination of anionic molecules over neutral species is demonstrated. Moreover, the membrane demonstrates high reproducibility, high scale-up potential, and excellent stability over two months.

Cellulose ternary photonic crystal created by solution processing

For the first time, a multiplanar photonic crystal structure has been obtained using cellulose as a structural material. This all-polymer system, made of cellulose, polyvinyl alcohol and poly(N-vinylcarbazole) is a ternary planar photonic crystal composed by 7 repeated trilayers produced by spin coating. Trimethylsilyl cellulose is used as a precursor to be converted to cellulose. Transverse Transmission Electron Microscopy analysis of our systems confirms the multilayered structure whose optical response can be theoretically accounted for. Preliminary results on the response of the photonic crystal to water vapors envisage the use of this system for humidity optical sensing.

The Cellulose Source Matters-Hollow Semi Spheres or Fibers by Needleless Electrospinning

An elegant way for the controlled production of either cellulose fibers or hollow half spheres from trimethylsilyl cellulose (TMSC) via needleless electrospinning is reported. For this purpose trimethylsilyl celluloses (DS: 2.6–2.7) have been synthesized from three different cellulose sources, namely spruce pulp, AVICEL, and a viscose pulp. While TMSC from AVICEL is hardly processable via electrospinning, the use of viscose pulps leads to hollow semi spheres, whereas the spruce pulp based TMSC yields fibrous networks. The approach takes advantage of different degrees of molecular entanglements caused by differences in origin and molecular weight of the cellulosic material. These investigations may pave the way for further use of electrospun materials made from TMSC in, e.g., sensor devices.

Ambipolar inverters with natural origin organic materials as gate dielectric and semiconducting layer.

Thin film electronics fabricated with non‐toxic and abundant materials are enabling for emerging bioelectronic technologies. Herein complementary‐like inverters comprising transistors using 6,6′‐dichloroindigo as the semiconductor and trimethylsilyl‐cellulose (TMSC) films on anodized aluminum as bilayer dielectric layer are demonstrated. The inverters operate both in the first and third quadrant, exhibiting a maximum static gain of 22 and a noise margin of 58% at a supply voltage of 14 V. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)

Crosslinked cellulose thin film composite nanofiltration membranes with zero salt rejection

We report a new synthetic route of fabricating regenerated cellulose nanofiltration membranes. The membranes are composite membranes with a thin selective layer of cellulose, which was prepared by regeneration of trimethylsilyl cellulose (a hydrophobic cellulose derivative) film followed by crosslinking. Filtration experiments using mixtures of sugar and sodium chloride showed that solutes above 300Da were highly rejected whereas practically no rejection was observed for NaCl. This is a big advantage for a complete desalination as the existing commercial nanofiltration membranes typically exhibit NaCl rejection in the range of 30–60%. Membranes with zero NaCl rejection are required for recovery and purification applications in food, chemical and pharmaceutical industry.

Cellulose-Derivative-Based Gate Dielectric for High-Performance Organic Complementary Inverters.

been realized using organic thin-fi lm transistors (OTFTs) as the essential element. In the majority of these applications OTFTs are integrated either in the form of arrays or as digital logic. The fundamental building block of digital logic is the inverter, a circuit that inverts an input signal. Much work has been devoted in the last fi ve years to design unipolar inverters using p-typeonly OTFTs. [ 18‐23 ] Unfortunately, unipolar logic based on single gate OTFTs always suffers from high power consumption and low noise margin coupled with high noise margin variability and therefore impedes the fabrication of complex circuits having hundreds or more logic gates. [ 19,22,23 ] In this context, it stands

Cellulose based thin films as a platform for drug release studies to mimick wound dressing materials

In this paper, the use of ultrathin cellulose supports as platform for the incorporation of analgesic drugs in wound dressings is proposed. As a model drug, diclofenac (DCF) is chosen, which is commonly used in pain easing medical treatments. The DCF containing cellulose films are prepared by mixing solutions of trimethylsilyl cellulose (DSSi:2.5) with DCF dissolved in THF. After depositing the material on a solid surface by spin-coating, the films are subjected to vapor-phase hydrolysis using 3 M HCl in order to achieve regeneration of cellulose. The release of DCF from these films over time is studied by UV–Vis. Upon deposition of additional layers of cellulose that do not contain DCF, the release from these films can be decelerated significantly. The release kinetics from these films is very similar to those of viscose fibers impregnated with DCF solutions. These studies indicate a potential use of cellulose thin films as model platform for viscose based wound dressings.

Photolithographic patterning of cellulose: a versatile dual-tone photoresist for advanced applications.

In many areas of science and technology, patterned films and surfaces play a key role in engineering and development of advanced materials. Here, we present a versatile toolbox that provides an easy patterning method for cellulose thin films by means of photolithography and enzymatic digestion. A patterned UV-illumination of trimethylsilyl cellulose thin films containing small amounts of a photo acid generator leads to a desilylation reaction and thus to the formation of cellulose in the irradiated areas. Depending on the conditions of development, either negative and positive type cellulose structures can be obtained, offering lateral resolutions down to the single-digit micro meter range by means of contact photolithography. In order to highlight the potential of this material for advanced patterning techniques, cellulose structures with sub-µm resolution are fabricated by means of two-photon absorption lithography. Moreover, these photochemically structured cellulose thin films are successfully implemented as dielectric layers in prototype organic thin film transistors. Such photopatternable dielectric layers are crucial for the realization of electrical interconnects for demanding organic device architectures.Electronic supplementary materialThe online version of this article (doi:10.1007/s10570-014-0471-4) contains supplementary material, which is available to authorized users.

Photoregeneration of trimethylsilyl cellulose as a tool for microstructuring ultrathin cellulose supports.

Microstructured thin films based on cellulose, the most abundant biopolymer on Earth, have been obtained by UV-irradiation of acid-labile trimethylsilyl cellulose thin films in the presence of N-hydroxynaphtalimide triflate as photoacid generator. We demonstrate that this photoregeneration process can be exploited for the manufacture of cellulose patterns having feature sizes down to 1 μm, with potential applications in life sciences.

Cellulose films: designing template-free nanoporous cellulose films on semiconducting surfaces.

In this work, we report the preparation of ultrathin submicro- and nanoporous cellulose films onto Si (100). The effect of different experimental conditions of preparation on the film surface morphology was studied, namely the role of the film casting method (spin- versus dip-coating), solvent (toluene or tetrahydrofuran), substrate pretreatment (hydrophilicity degree), and regeneration procedure with HCl vapors (two consecutive dips followed by regeneration or regeneration after each dip). The surface morphological structures presented in this work were never obtained before without the use of templates. A rather regular two-dimensional pore network was obtained onto the less hydrophilic Si substrate (contact angle≅68°), after two consecutive dips (with an intercalary rotation of 180º) in trimethylsilyl cellulose diluted in toluene and regeneration at the end. All the surfaces were characterized by atomic force microscopy.

Photoreductive generation of amorphous bismuth nanoparticles using polysaccharides--bismuth-cellulose nanocomposites.

A simple and highly reproducible synthesis of amorphous bismuth nanoparticles incorporated into a polysaccharide matrix using a photoreduction process is presented. As precursor for the generation of the Bi nanoparticles, organosoluble triphenylbismuth is used. The precursor is dissolved in toluene and mixed with a hydrophobic organosoluble polysaccharide, namely trimethylsilyl cellulose (TMSC) with high DSSi. The solution is subjected to UV exposure, which induces the homolytic cleavage of the bismuth-carbon bond in BiPh3 resulting in the formation of Bi(0) and phenyl radicals. The aggregation of the Bi atoms can be controlled in the TMSC matrix and yields nanoparticles of around 20 nm size as proven by TEM. The phenyl radicals undergo recombination to form small organic molecules like benzene and biphenyl, which can be removed from the nanocomposite after lyophilization and exposure to high vacuum. Finally, the TMSC matrix is converted to cellulose after exposure to HCl vapors, which remove the trimethylsilyl groups from the TMSC derivative. Although TMSC is converted to cellulose, the formed TMS-OH is not leaving the nanocomposite but reacts instead with surface oxide layer of the Bi nanoparticles to form silylated Bi nanoparticles as proven by TEM/EDX.

A study on the interaction of cationized chitosan with cellulose surfaces

This investigation describes the interaction of trimethyl chitosans (TMCs) with surfaces of cellulose thin films. The irreversible deposition/adsorption of TMCs with different degrees of cationization was studied with regards to the salt concentration and pH. As substrates, cellulose thin films were prepared by spin coating from trimethylsilyl cellulose and subsequent regeneration to pure cellulose. The pH-dependent zeta potential of cellulose thin films and the charge of TMCs were determined by streaming potential and potentiometric charge titration methods. A quartz crystal microbalance with dissipation monitoring was further used as a nanogram sensitive balance to detect the amount of deposited TMCs and the swelling of the bound layers. The morphology of the coatings was additionally characterized by atomic force microscopy and related to the adsorption results. A lower degree of cationization leads to higher amounts of deposited TMCs at all salt concentrations. Higher amounts of salt increase the deposition of TMCs. Protonation of primary amino groups results in the immobilization of less material at lower pH values. The results from this work can further be extended to the modification of regenerated cellulosic materials to obtain surfaces, with amino- and trimethylammonium moieties.

2D dendritic fractal patterns from an amphiphilic polysaccharide

Fractals are ubiquitous in nature and they are also useful in many modern applications because they are able to incorporate multiple length scales within the same material. However, the bottom-up construction of fractals has been difficult because the physico-chemical principles that underpin the fractal formation have remained elusive. Here, an experimental model setup was used to investigate the emergence of fractals in 2D: Langmuir-Schaefer deposition of an amphiphilic polysaccharide (namely, trimethylsilyl cellulose, TMSC) on substrates with systematically varying surface free energies. Continuous monolayers of TMSC on water appeared to turn into 2D fractal patterns when deposited horizontally on a solid substrate of low surface free energy such as hydrophobically modified (methylated) silica. The decreased surface energy results in higher entropy, which enables fractal formation, as fractals have the highest degree of uncertainty of all 2D patterns. Furthermore, morphological changes within the fractals during a chemical reaction and water immersion were investigated. The results provide a starting point for a better understanding of the bottom-up construction of 2D fractal patterns from soft materials.