TY - JOUR A1 - Hiltl, Stephanie A1 - Böker, Alexander T1 - Wetting Phenomena on (Gradient) Wrinkle Substrates JF - Langmuir N2 - We characterize the wetting behavior of nano structured wrinkle and gradient wrinkle substrates. Different contact angles on both sides of a water droplet after deposition on a gradient sample induce the self-propelled motion of the liquid toward smaller wrinkle dimensions. The droplet motion is self-limited by the contact angles balancing out. Because of the correlation between droplet motion and contact angles, we investigate the wetting behavior of wrinkle substrates with constant dimensions (wavelengths of 400-1200 nm). Contact angles of water droplets on those substrates increase with increasing dimensions of the underlying substrate. The results are independent of the two measurement directions, parallel and perpendicular to the longitudinal axis of the nanostructure. The presented findings may be considered for designing microfluidic or related devices and initiate ideas for the development of further wrinkle applications. Y1 - 2016 U6 - https://doi.org/10.1021/acs.langmuir.6b02364 SN - 0743-7463 VL - 32 SP - 8882 EP - 8888 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Wagner, Tom A1 - Oded, Meirav A1 - Shenhar, Roy A1 - Böker, Alexander T1 - Two-dimensionally ordered AuNP array formation via microcontact printing on lamellar diblock copolymer films JF - Polymers for advanced technologies N2 - The construction of nano-sized, two-dimensionally ordered nanoparticle (NP) superstructures is important for various advanced applications such as photonics, sensing, catalysis, or nano-circuitry. Currently, such structures are fabricated using the templated organization approach, in which the templates are mainly created by photo-lithography or laser-lithography and other invasive top-down etching procedures. In this work, we present an alternative bottom-up preparation method for the controlled deposition of NPs into hierarchical structures. Lamellar polystyrene-block-poly(2-vinylpyridinium) thin films featuring alternating stripes of neutral PS and positively charged P2VP domains serve as templates, allowing for the selective adsorption of negatively charged gold NPs. Dense NP assembly is achieved by a simple immersion process, whereas two-dimensionally ordered arrays of NPs are realized by microcontact printing (mu CP), utilizing periodic polydimethylsiloxane wrinkle grooves loaded with gold NPs. This approach enables the facile construction of hierarchical NP arrays with variable geometries. Copyright (C) 2016 John Wiley & Sons, Ltd. KW - block copolymers KW - electrostatic assembly KW - microcontact printing KW - gold nanoparticles Y1 - 2017 U6 - https://doi.org/10.1002/pat.3853 SN - 1042-7147 SN - 1099-1581 VL - 28 SP - 623 EP - 628 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Cheng, Xiao A1 - Böker, Alexander A1 - Tsarkova, Larisa T1 - Temperature-Controlled Solvent Vapor Annealing of Thin Block Copolymer Films JF - Polymers N2 - Solvent vapor annealing is as an effective and versatile alternative to thermal annealing to equilibrate and control the assembly of polymer chains in thin films. Here, we present scientific and practical aspects of the solvent vapor annealing method, including the discussion of such factors as non-equilibrium conformational states and chain dynamics in thin films in the presence of solvent. Homopolymer and block copolymer films have been used in model studies to evaluate the robustness and the reproducibility of the solvent vapor processing, as well as to assess polymer-solvent interactions under confinement. Advantages of utilizing a well-controlled solvent vapor environment, including practically interesting regimes of weakly saturated vapor leading to poorly swollen states, are discussed. Special focus is given to dual temperature control over the set-up instrumentation and to the potential of solvo-thermal annealing. The evaluated insights into annealing dynamics derived from the studies on block copolymer films can be applied to improve the processing of thin films of crystalline and conjugated polymers as well as polymer composite in confined geometries. KW - solvent vapor annealing KW - block copolymer films KW - ellipsometry KW - guided self assembly Y1 - 2019 U6 - https://doi.org/10.3390/polym11081312 SN - 2073-4360 VL - 11 IS - 8 PB - MDPI CY - Basel ER - TY - JOUR A1 - Sperling, Marcel A1 - Reifarth, Martin A1 - Grobe, Richard A1 - Böker, Alexander T1 - Tailoring patches on particles: a modified microcontact printing routine using polymer-functionalised stamps JF - Chemical communications N2 - Herein, we report a modified microcontact printing (mu CP) routine suitable to introduce particle patches of a low molecular weight ink (LMWI) on porous SiO2 microparticles. Thereby, patch precision could be significantly improved by utilising stamps which have been surface-functionalised with grafted polymers. This improvement was evaluated by a profound software-assisted statistical analysis. Y1 - 2019 U6 - https://doi.org/10.1039/c9cc03903a SN - 1359-7345 SN - 1364-548X VL - 55 IS - 68 SP - 10104 EP - 10107 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Tan, Li A1 - Liu, Bing A1 - Siemensmeyer, Konrad A1 - Glebe, Ulrich A1 - Böker, Alexander T1 - Synthesis of thermo-responsive nanocomposites of superparamagnetic cobalt nanoparticlesipoly(N-isopropylacrylamide) JF - Journal of colloid and interface science N2 - Novel nanocomposites of superparamagnetic cobalt nanoparticles (Co NPs) and poly(N-isopropylacrylamide) (PNIPAM) were fabricated through surface-initiated atom-transfer radical polymerization (SI-ATRP). We firstly synthesized a functional ATRP initiator, containing an amine (as anchoring group) and a 2-bromopropionate group (SI-ATRP initiator). Oleic acid- and trioctylphosphine oxide-coated Co NPs were then modified with the initiator via ligand exchange. The process is facile and rapid for efficient surface functionalization and afterwards the Co NPs can be dispersed into polar solvent DMF without aggregation. Transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and dynamic light scattering measurements confirmed the success of ligand exchange. The following polymerization of NIPAM was conducted on the surface of Co NPs. Temperature-dependent dynamic light scattering study showed the responsive behavior of PNIPAM-coated Co NPs. The combination of superparamagnetic and thermo-responsive properties in these hybrid nanoparticles is promising for future applications e.g. in biomedicine. (C) 2018 Elsevier Inc. All rights reserved. KW - Nanoparticles KW - Superparamagnetic KW - Surface-initiated atom-transfer radical KW - polymerization KW - Responsivity Y1 - 2018 U6 - https://doi.org/10.1016/j.jcis.2018.04.074 SN - 0021-9797 SN - 1095-7103 VL - 526 SP - 124 EP - 134 PB - Elsevier CY - San Diego ER - TY - JOUR A1 - Tan, Li A1 - Liu, Bing A1 - Siemensmeyer, Konrad A1 - Glebe, Ulrich A1 - Böker, Alexander T1 - Synthesis of Polystyrene-Coated Superparamagnetic and Ferromagnetic Cobalt Nanoparticles JF - Polymers N2 - Polystyrene-coated cobalt nanoparticles (NPs) were synthesized through a dual-stage thermolysis of cobalt carbonyl (Co-2(CO)(8)). The amine end-functionalized polystyrene surfactants with varying molecular weight were prepared via atom-transfer radical polymerization technique. By changing the concentration of these polymeric surfactants, Co NPs with different size, size distribution, and magnetic properties were obtained. Transmission electron microscopy characterization showed that the size of Co NPs stabilized with lower molecular weight polystyrene surfactants (M-n = 2300 g/mol) varied from 12-22 nm, while the size of Co NPs coated with polystyrene of middle (M-n = 4500 g/mol) and higher molecular weight (M-n = 10,500 g/mol) showed little change around 20 nm. Magnetic measurements revealed that the small cobalt particles were superparamagnetic, while larger particles were ferromagnetic and self-assembled into 1-D chain structures. Thermogravimetric analysis revealed that the grafting density of polystyrene with lower molecular weight is high. To the best of our knowledge, this is the first study to obtain both superparamagnetic and ferromagnetic Co NPs by changing the molecular weight and concentration of polystyrene through the dual-stage decomposition method. KW - cobalt nanoparticles KW - polystyrene KW - superparamagnetic KW - ferromagnetic KW - molecular weight Y1 - 2018 U6 - https://doi.org/10.3390/polym10101053 SN - 2073-4360 VL - 10 IS - 10 PB - MDPI CY - Basel ER - TY - JOUR A1 - Doering, Ulrike A1 - Grigoriev, Dmitry A1 - Tapio, Kosti A1 - Bald, Ilko A1 - Böker, Alexander T1 - Synthesis of nanostructured protein-mineral-microcapsules by sonication JF - Soft matter N2 - We propose a simple and eco-friendly method for the formation of composite protein-mineral-microcapsules induced by ultrasound treatment. Protein- and nanoparticle-stabilized oil-in-water (O/W) emulsions loaded with different oils are prepared using high-intensity ultrasound. The formation of thin composite mineral proteinaceous shells is realized with various types of nanoparticles, which are pre-modified with Bovine Serum Albumin (BSA) and subsequently characterized by EDX, TGA, zeta potential measurements and Raman spectroscopy. Cryo-SEM and EDX mapping visualizations show the homogeneous distribution of the densely packed nanoparticles in the capsule shell. In contrast to the results reported in our previous paper,(1) the shell of those nanostructured composite microcapsules is not cross-linked by the intermolecular disulfide bonds between BSA molecules. Instead, a Pickering-Emulsion formation takes place because of the amphiphilicity-driven spontaneous attachment of the BSA-modified nanoparticles at the oil/water interface. Using colloidal particles for the formation of the shell of the microcapsules, in our case silica, hydroxyapatite and calcium carbonate nanoparticles, is promising for the creation of new functional materials. The nanoparticulate building blocks of the composite shell with different chemical, physical or morphological properties can contribute to additional, sometimes even multiple, features of the resulting capsules. Microcapsules with shells of densely packed nanoparticles could find interesting applications in pharmaceutical science, cosmetics or in food technology. Y1 - 2022 U6 - https://doi.org/10.1039/d1sm01638e SN - 1744-6848 VL - 18 IS - 13 SP - 2558 EP - 2568 PB - Royal Society of Chemistry CY - London ER - TY - JOUR A1 - Wu, Lei A1 - Glebe, Ulrich A1 - Böker, Alexander T1 - Synthesis of Hybrid Silica Nanoparticles Densely Grafted with Thermo and pH Dual-Responsive Brushes via Surface-Initiated ATRP JF - Macromolecules : a publication of the American Chemical Society Y1 - 2016 U6 - https://doi.org/10.1021/acs.macromol.6b01792 SN - 0024-9297 SN - 1520-5835 VL - 49 SP - 9586 EP - 9596 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Liebeck, Bernd Michael A1 - Hidalgo, Natalia A1 - Roth, Georg A1 - Popescu, Crisan A1 - Böker, Alexander T1 - Synthesis and characterization of Methyl Cellulose/Keratin Hydrolysate Composite Membranes JF - Polymers / Molecular Diversity Preservation International N2 - It is known that aqueous keratin hydrolysate solutions can be produced from feathers using superheated water as solvent. This method is optimized in this study by varying the time and temperature of the heat treatment in order to obtain a high solute content in the solution. With the dissolved polypeptides, films are produced using methyl cellulose as supporting material. Thereby, novel composite membranes are produced from bio-waste. It is expected that these materials exhibit both protein and polysaccharide properties. The influence of the embedded keratin hydrolysates on the methyl cellulose structure is investigated using Fourier transform infrared spectroscopy (FTIR) and wide angle X-ray diffraction (WAXD). Adsorption peaks of both components are present in the spectra of the membranes, while the X-ray analysis shows that the polypeptides are incorporated into the semi-crystalline methyl cellulose structure. This behavior significantly influences the mechanical properties of the composite films as is shown by tensile tests. Since further processing steps, e.g., crosslinking, may involve a heat treatment, thermogravimetric analysis (TGA) is applied to obtain information on the thermal stability of the composite materials. KW - bio-based KW - composite materials KW - methyl cellulose KW - keratin KW - superheated water Y1 - 2017 U6 - https://doi.org/10.3390/polym9030091 SN - 2073-4360 VL - 9 PB - MDPI CY - Basel ER - TY - JOUR A1 - Sechi, Antonio A1 - Freitas, Joana M. G. A1 - Wünnemann, Patrick A1 - Töpel, Alexander A1 - Paschoalin, Rafaella Takehara A1 - Ullmann, Sabrina A1 - Schröder, Ricarda A1 - Aydin, Gülcan A1 - Rütten, Stephan A1 - Böker, Alexander A1 - Zenke, Martin A1 - Pich, Andrij T1 - Surface-Grafted Nanogel Arrays Direct Cell Adhesion and Motility JF - Advanced materials interfaces N2 - It has long been appreciated that material chemistry and topology profoundly affect cell adhesion and migration. Here, aqueous poly(N- isopropyl acrylamide) nanogels are designed, synthesized and printed in form of colloidal arrays on glass substrates using wrinkled polydimethylsiloxane templates. Using low-temperature plasma treatment, nanogels are chemically grafted onto glass supports thus leading to highly stable nanogel layers in cell culture media. Liquid cell atomic force microscopy investigations show that surface-grafted nanogels retain their swelling behavior in aqueous media and that extracellular matrix protein coating do not alter their stability and topography. It is demonstrated that surface-grafted nanogels could serve as novel substrates for the analysis of cell adhesion and migration. Nanogels influence size, speed, and dynamics of focal adhesions and cell motility forcing cells to move along highly directional trajectories. Moreover, modulation of nanogel state or spacing serves as an effective tool for regulation of cell motility. It is suggested that nanogel arrays deposited on solid surfaces could be used to provide a precise and tunable system to understand and control cell migration. Additionally, such nanogel arrays will contribute to the development of implantable systems aimed at supporting and enhancing cell migration during, for instance, wound healing and tissue regeneration. Y1 - 2016 U6 - https://doi.org/10.1002/admi.201600455 SN - 2196-7350 VL - 3 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Dai, Xiaolin A1 - Mate, Diana M. A1 - Glebe, Ulrich A1 - Garakani, Tayebeh Mirzaei A1 - Körner, Andrea A1 - Schwaneberg, Ulrich A1 - Böker, Alexander T1 - Sortase-mediated ligation of purely artificial building blocks JF - Polymers N2 - Sortase A (SrtA) from Staphylococcus aureus has been often used for ligating a protein with other natural or synthetic compounds in recent years. Here we show that SrtA-mediated ligation (SML) is universally applicable for the linkage of two purely artificial building blocks. Silica nanoparticles (NPs), poly(ethylene glycol) and poly(N-isopropyl acrylamide) are chosen as synthetic building blocks. As a proof of concept, NP-polymer, NP-NP, and polymer-polymer structures are formed by SrtA catalysis. Therefore, the building blocks are equipped with the recognition sequence needed for SrtA reaction-the conserved peptide LPETG-and a pentaglycine motif. The successful formation of the reaction products is shown by means of transmission electron microscopy (TEM), matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-ToF MS), and dynamic light scattering (DLS). The sortase catalyzed linkage of artificial building blocks sets the stage for the development of a new approach to link synthetic structures in cases where their synthesis by established chemical methods is complicated. KW - sortase-mediated ligation KW - enzymes KW - block copolymers KW - nanoparticles Y1 - 2018 U6 - https://doi.org/10.3390/polym10020151 SN - 2073-4360 VL - 10 IS - 2 PB - MDPI CY - Basel ER - TY - JOUR A1 - Akarsu, Pinar A1 - Grobe, Richard A1 - Nowaczyk, Julius A1 - Hartlieb, Matthias A1 - Reinicke, Stefan A1 - Böker, Alexander A1 - Sperling, Marcel A1 - Reifarth, Martin T1 - Solid-phase microcontact printing for precise patterning of rough surfaces BT - using polymer-tethered elastomeric stamps for the transfer of reactive silanes JF - ACS applied polymer materials N2 - We present a microcontact printing (mu CP) routine suitable to introduce defined (sub-) microscale patterns on surface substrates exhibiting a high capillary activity and receptive to a silane-based chemistry. This is achieved by transferring functional trivalent alkoxysilanes, such as (3-aminopropyl)-triethoxysilane (APTES) as a low-molecular weight ink via reversible covalent attachment to polymer brushes grafted from elastomeric polydimethylsiloxane (PDMS) stamps. The brushes consist of poly{N-[tris(hydroxymethyl)-methyl]acrylamide} (PTrisAAm) synthesized by reversible addition-fragmentation chain-transfer (RAFT)-polymerization and used for immobilization of the alkoxysilane-based ink by substituting the alkoxy moieties with polymer-bound hydroxyl groups. Upon physical contact of the silane-carrying polymers with surfaces, the conjugated silane transfers to the substrate, thus completely suppressing ink-flow and, in turn, maximizing printing accuracy even for otherwise not addressable substrate topographies. We provide a concisely conducted investigation on polymer brush formation using atomic force microscopy (AFM) and ellipsometry as well as ink immobilization utilizing two-dimensional proton nuclear Overhauser enhancement spectroscopy (H-1-H-1-NOESY-NMR). We analyze the mu CP process by printing onto Si-wafers and show how even distinctively rough surfaces can be addressed, which otherwise represent particularly challenging substrates. KW - microcontact printing KW - capillary-active substrates KW - silane chemistry KW - PDMS surface grafting KW - surface patterning KW - shuttled RAFT-polymerization Y1 - 2021 U6 - https://doi.org/10.1021/acsapm.1c00024 SN - 2637-6105 VL - 3 IS - 5 SP - 2420 EP - 2431 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Wang, Xuepu A1 - Sperling, Marcel A1 - Reifarth, Martin A1 - Böker, Alexander T1 - Shaping metallic nanolattices BT - Design by microcontact printing from wrinkled stamps JF - Small N2 - A method for the fabrication of well-defined metallic nanostructures is presented here in a simple and straightforward fashion. As an alternative to lithographic techniques, this routine employs microcontact printing utilizing wrinkled stamps, which are prepared from polydimethylsiloxane (PDMS), and includes the formation of hydrophobic stripe patterns on a substrate via the transfer of oligomeric PDMS. Subsequent backfilling of the interspaces between these stripes with a hydroxyl-functional poly(2-vinyl pyridine) then provides the basic pattern for the deposition of citrate-stabilized gold nanoparticles promoted by electrostatic interaction. The resulting metallic nanostripes can be further customized by peeling off particles in a second microcontact printing step, which employs poly(ethylene imine) surface-decorated wrinkled stamps, to form nanolattices. Due to the independent adjustability of the period dimensions of the wrinkled stamps and stamp orientation with respect to the substrate, particle arrays on the (sub)micro-scale with various kinds of geometries are accessible in a straightforward fashion. This work provides an alternative, cost-effective, and scalable surface-patterning technique to fabricate nanolattice structures applicable to multiple types of functional nanoparticles. Being a top-down method, this process could be readily implemented into, e.g., the fabrication of optical and sensing devices on a large scale. KW - gold nanoparticle assembly KW - hydroxyl-functional poly(2-vinyl pyridine) KW - metallic nanolattices KW - microcontact printing KW - oligomeric KW - polydimethylsiloxane KW - polydimethylsiloxane wrinkles KW - wrinkled stamps Y1 - 2020 U6 - https://doi.org/10.1002/smll.201906721 SN - 1613-6810 SN - 1613-6829 VL - 16 IS - 11 SP - 1 EP - 8 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Mehr, Fatemeh Naderi A1 - Grigoriev, Dmitry A1 - Heaton, Rebecca A1 - Baptiste, Joshua A1 - Stace, Anthony J. A1 - Puretskiy, Nikolay A1 - Besley, Elena A1 - Böker, Alexander T1 - Self-assembly behavior of oppositely charged inverse bipatchy microcolloids JF - Small : nano micro N2 - A directed attractive interaction between predefined "patchy" sites on the surfaces of anisotropic microcolloids can provide them with the ability to self-assemble in a controlled manner to build target structures of increased complexity. An important step toward the controlled formation of a desired superstructure is to identify reversible electrostatic interactions between patches which allow them to align with one another. The formation of bipatchy particles with two oppositely charged patches fabricated using sandwich microcontact printing is reported. These particles spontaneously self-aggregate in solution, where a diversity of short and long chains of bipatchy particles with different shapes, such as branched, bent, and linear, are formed. Calculations show that chain formation is driven by a combination of attractive electrostatic interactions between oppositely charged patches and the charge-induced polarization of interacting particles. KW - electrostatic interactions KW - patchy particles KW - polyelectrolyte inks KW - sandwich microcontact printing KW - self-assembly Y1 - 2020 U6 - https://doi.org/10.1002/smll.202000442 SN - 1613-6810 SN - 1613-6829 VL - 16 IS - 14 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Liedel, Clemens A1 - Lewin, Christian A1 - Tsarkova, Larisa A1 - Böker, Alexander T1 - Reversible Switching of Block Copolymer Nanopatterns by Orthogonal Electric Fields JF - Small N2 - It is demonstrated that the orientation of striped patterns can be reversibly switched between two perpendicular in-plane orientations upon exposure to electric fields. The results on thin films of symmetric polystyrene-block-poly(2-vinyl pyridine) polymer in the intermediate segregation regime disclose two types of reorientation mechanisms from perpendicular to parallel relative to the electric field orientation. Domains orient via grain rotation and via formation of defects such as stretched undulations and temporal phase transitions. The contribution of additional fields to the structural evolution is also addressed to elucidate the generality of the observed phenomena. In particular solvent effects are considered. This study reveals the stabilization of the meta-stable in-plane oriented lamella due to sequential swelling and quenching of the film. Further, the reorientation behavior of lamella domains blended with selective nanoparticles is addressed, which affect the interfacial tensions of the blocks and hence introduce another internal field to the studied system. Switching the orientation of aligned block copolymer patterns between two orthogonal directions may open new applications of nanomaterials as switchable electric nanowires or optical gratings. KW - alignments KW - block copolymers KW - electric fields KW - reorientation KW - solvent vapor annealing KW - polymers Y1 - 2015 U6 - https://doi.org/10.1002/smll.201502259 SN - 1613-6810 SN - 1613-6829 VL - 11 IS - 45 SP - 6058 EP - 6064 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Kathrein, Christine C. A1 - Pester, Christian A1 - Ruppel, Markus A1 - Jung, Maike A1 - Zimmermann, Marc A1 - Böker, Alexander T1 - Reorientation mechanisms of block copolymer/CdSe quantum dot composites under application of an electric field JF - Soft matter N2 - Time- and temperature-resolved in situ birefringence measurements were applied to analyze the effect of nanoparticles on the electric field-induced alignment of a microphase separated solution of poly(styrene)-block-poly(isoprene) in toluene. Through the incorporation of isoprene-confined CdSe quantum dots the reorientation behavior is altered. Particle loading lowers the order-disorder transition temperature, and increases the defect density, favoring nucleation and growth as an alignment mechanism over rotation of grains. The temperature dependent alteration in the reorientation mechanism is analyzed via a combination of birefringence and synchrotron SAXS. The detailed understanding of the effect of nanoparticles on the reorientation mechanism is an important prerequisite for optimization of electricfield-induced alignment of block copolymer/nanoparticle composites where the block copolymer guides the nanoparticle self-assembly into anisotropic structures. Y1 - 2016 U6 - https://doi.org/10.1039/c6sm01073c SN - 1744-683X SN - 1744-6848 VL - 12 SP - 8417 EP - 8424 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Leiendecker, Mai-Thi A1 - Licht, Christopher J. A1 - Borghs, Jannik A1 - Mooney, David J. A1 - Zimmermann, Marc A1 - Böker, Alexander T1 - Physical polyurethane hydrogels via charge shielding through acids or salts JF - Macromolecular rapid communications N2 - Physical hydrogels with tunable stress-relaxation and excellent stress recovery are formed from anionic polyurethanes via addition of acids, monovalent salts, or divalent salts. Gel properties can be widely adjusted through pH, salt valence, salt concentration, and monomer composition. We propose and investigate a novel gelation mechanism based on a colloidal system interacting through charge repulsion and chrage shielding, allowing a broad use of the material, from acidic (pH 4–5.5) to pH-neutral hydrogels with Young's moduli ranging from 10 to 140 kPa. KW - acidic crosslinking KW - charge repulsion KW - charge shielding KW - ionic crosslinking KW - physical hydrogels KW - polyurethanes KW - stress recovery KW - stress-relaxation Y1 - 2018 U6 - https://doi.org/10.1002/marc.201700711 SN - 1022-1336 SN - 1521-3927 VL - 39 IS - 7 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Zimmermann, Marc A1 - Stomps, Benjamin René Harald A1 - Schulte-Osseili, Christine A1 - Grigoriev, Dmitry A1 - Ewen, Dirk A1 - Morgan, Andrew A1 - Böker, Alexander T1 - Organic dye anchor peptide conjugates as an advanced coloring agent for polypropylene yarn JF - Textile Research Journal N2 - Polypropylene as one of the world's top commodity polymers is also widely used in the textile industry. However, its non-polar nature and partially crystalline structure significantly complicate the process of industrial coloring of polypropylene. Currently, textiles made of polypropylene or with a significant proportion of polypropylene are dyed under quite harsh conditions, including the use of high pressures and temperatures, which makes this process energy intensive. This research presents a three-step synthesis of coloring agents, capable of adhering onto synthetic polypropylene yarns without harsh energy-consuming conditions. This is possible by encapsulation of organic pigments using trimethoxyphenylsilane, introduction of surface double bonds via modification of the silica shell with trimethoxysilylpropylmethacrylate and final attachment of highly adhesive anchor peptides using thiol-ene chemistry. We demonstrate the applicability of this approach by dyeing polypropylene yarns in a simple process under ambient conditions after giving a step-by-step guide for the synthesis of these new dyeing agents. Finally, the successful dyeing of the yarns is visualized, and its practicability is discussed. KW - anchor peptides KW - organic dye pigments KW - coloring agents KW - polypropylene KW - yarns Y1 - 2020 U6 - https://doi.org/10.1177/0040517520932231 SN - 0040-5175 SN - 1746-7748 VL - 91 IS - 1-2 SP - 28 EP - 39 PB - Sage Publ. CY - London ER - TY - JOUR A1 - Charan, Himanshu A1 - Glebe, Ulrich A1 - Anand, Deepak A1 - Kinzel, Julia A1 - Zhu, Leilei A1 - Bocola, Marco A1 - Garakani, Tayebeh Mirzaei A1 - Schwaneberg, Ulrich A1 - Böker, Alexander T1 - Nano-thin walled micro-compartments from transmembrane protein-polymer conjugates JF - Soft matter N2 - The high interfacial activity of protein-polymer conjugates has inspired their use as stabilizers for Pickering emulsions, resulting in many interesting applications such as synthesis of templated micro-compartments and protocells or vehicles for drug and gene delivery. In this study we report, for the first time, the stabilization of Pickering emulsions with conjugates of a genetically modified transmembrane protein, ferric hydroxamate uptake protein component A (FhuA). The lysine residues of FhuA with open pore (FhuA Delta CVFtev) were modified to attach an initiator and consequently controlled radical polymerization (CRP) carried out via the grafting-from technique. The resulting conjugates of FhuA Delta CVFtev with poly(N-isopropylacrylamide) (PNIPAAm) and poly((2-dimethylamino) ethyl methacrylate) (PDMAEMA), the so-called building blocks based on transmembrane proteins (BBTP), have been shown to engender larger structures. The properties such as pH-responsivity, temperature-responsivity and interfacial activity of the BBTP were analyzed using UV-Vis spectrophotometry and pendant drop tensiometry. The BBTP were then utilized for the synthesis of highly stable Pickering emulsions, which could remain non-coalesced for well over a month. A new UV-crosslinkable monomer was synthesized and copolymerized with NIPAAm from the protein. The emulsion droplets, upon crosslinking of polymer chains, yielded micro-compartments. Fluorescence microscopy proved that these compartments are of micrometer scale, while cryo-scanning electron microscopy and scanning force microscopy analysis yielded a thickness in the range of 11.1 +/- 0.6 to 38.0 +/- 18.2 nm for the stabilizing layer of the conjugates. Such micro-compartments would prove to be beneficial in drug delivery applications, owing to the possibility of using the channel of the transmembrane protein as a gate and the smart polymer chains as trigger switches to tune the behavior of the capsules. Y1 - 2017 U6 - https://doi.org/10.1039/c6sm02520j SN - 1744-683X SN - 1744-6848 VL - 13 SP - 2866 EP - 2875 PB - Royal Society of Chemistry CY - Cambridge ER - TY - JOUR A1 - Mehr, Fatemeh Naderi A1 - Grigoriev, Dmitry A1 - Puretskiy, Nikolay A1 - Böker, Alexander T1 - Mono-patchy zwitterionic microcolloids as building blocks for pH-controlled self-assembly JF - Soft matter N2 - A directional molecular interaction between microcolloids can be achieved through pre-defined sites on their surface, patches, which might make them follow each other in a controlled way and assemble into target structures of more complexity. In this article, we report the successful generation and characterization of mono-patchy melamine-formaldehyde microparticles with oppositely charged patches made of poly(methyl vinyl ether-alt-maleic acid) or polyethyleneimine via microcontact printing. The study of their self-aggregation behavior in solution shows that by change of pH, particle dimers are formed via attractive electrostatic force between the patchy and non-patchy surface of the particles, which reaches its optimum at a specific pH. Y1 - 2019 U6 - https://doi.org/10.1039/c8sm02151a SN - 1744-683X SN - 1744-6848 VL - 15 IS - 11 SP - 2430 EP - 2438 PB - Royal Society of Chemistry CY - Cambridge ER -