Browsing by Author "Möller, Martin"
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- Item4D Printing of a Light-Driven Soft Actuator with Programmed Printing Density(Washington, DC : ACS Publications, 2020) Nishiguchi, Akihiro; Zhang, Hang; Schweizerhof, Sjören; Schulte, Marie Friederike; Mourran, Ahmed; Möller, MartinThere is a growing interest in the concept of four-dimensional (4D) printing that combines a three-dimensional (3D) manufacturing process with dynamic modulation for bioinspired soft materials exhibiting more complex functionality. However, conventional approaches have drawbacks of low resolution, control of internal micro/nanostructure, and creation of fast, complex actuation due to a lack of high-resolution fabrication technology and suitable photoresist for soft materials. Here, we report an approach of 4D printing that develops a bioinspired soft actuator with a defined 3D geometry and programmed printing density. Multiphoton lithography (MPL) allows for controlling printing density in gels at pixel-by-pixel with a resolution of a few hundreds of nanometers, which tune swelling behaviors of gels in response to external stimuli. We printed a 3D soft actuator composed of thermoresponsive poly(N-isopropylacrylamide) (PNIPAm) and gold nanorods (AuNRs). To improve the resolution of printing, we synthesized a functional, thermoresponsive macrocrosslinker. Through plasmonic heating by AuNRs, nanocomposite-based soft actuators undergo nonequilibrium, programmed, and fast actuation. Light-mediated manufacture and manipulation (MPL and photothermal effect) offer the feasibility of 4D printing toward adaptive bioinspired soft materials. Copyright © 2020 American Chemical Society.
- ItemActively Tunable Collective Localized Surface Plasmons by Responsive Hydrogel Membrane(Weinheim : Wiley-VCH, 2019) Quilis, Nestor Gisbert; van Dongen, Marcel; Venugopalan, Priyamvada; Kotlarek, Daria; Petri, Christian; Cencerrado, Alberto Moreno; Stanescu, Sorin; Herrera, Jose Luis Toca; Jonas, Ulrich; Möller, Martin; Mourran, Ahmed; Dostalek, JakubCollective (lattice) localized surface plasmons (cLSP) with actively tunable and extremely narrow spectral characteristics are reported. They are supported by periodic arrays of gold nanoparticles attached to a stimuli-responsive hydrogel membrane, which can on demand swell and collapse to reversibly modulate arrays period and surrounding refractive index. In addition, it features a refractive index-symmetrical geometry that promotes the generation of cLSPs and leads to strong suppression of radiative losses, narrowing the spectral width of the resonance, and increasing of the electromagnetic field intensity. Narrowing of the cLSP spectral band down to 13 nm and its reversible shifting by up to 151 nm is observed in the near infrared part of the spectrum by varying temperature and by solvent exchange for systems with a poly(N-isopropylacrylamide)-based hydrogel membrane that is allowed to reversibly swell and collapse in either one or in three dimensions. The reported structures with embedded periodic gold nanoparticle arrays are particularly attractive for biosensing applications as the open hydrogel structure can be efficiently post-modified with functional moieties, such as specific ligands, and since biomolecules can rapidly diffuse through swollen polymer networks. © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
- ItemApproach to Obtain Electrospun Hydrophilic Fibers and Prevent Fiber Necking(New York, NY [u.a.] : Wiley InterScience, 2019) Fischer, Thorsten; Möller, Martin; Singh, SmritiSolution electrospinning of a blend containing a hydrophobic polymer with a hydrophilic functional polymer as an additive is a simple and straight-forward route to obtain functional and hydrophilic fibers accompanied by the mechanical properties of the hydrophobic polymer. However, this process of thermodynamically unfavored surface segregation of the hydrophilic additive is not well understood. To understand the process the dependencies of the surface hydrophilization on type of hydrophilic polymers, the solvent, and the process, using poly(caprolactone) (PCL) as the matrix polymer is explored. The results show that hydrophilic fibers can be obtained using different additive hydrophilic polymers. The combination of polymer blends which show this effect can be predicted using the Flory–Huggins interaction parameter. In addition mechanical and micromechanical properties of PCL fibers blended with NCO-terminated star-shaped poly(ethylene glycol) (sPEG-NCO) as additive are investigated. In this context blending with sPEG-NCO turns out to be a powerful tool to prevent fiber necking rendering this method an interesting candidate for tissue engineering application, where it is mandatory to retain the surface properties under mechanical stress.
- ItemBilliards, Flat Surfaces, and Dynamics on Moduli Spaces(Zürich : EMS Publ. House, 2011) Möller, Martin; Zorich, AntonThis workshop brought together people working on the dynamics of various flows on moduli spaces, in particular the action of SL$_2(\mathbb R)$ on flat surfaces. The new results presented covered properties of interval exchange transformations, Lyapunov spectrum of this flow and the geometry of Teichmüller space.
- ItemBioTransporter - effizienter Wirkstofftransport in biologischen Systemen : Verbundprojekt Wirkstofffreisetzungssysteme für den Urogenitaltrakt - DUro, Teilvorhaben: Entwicklung aktiver Mikrosphären zur Freisetzung urologisch relevanter Medikamente ; Schlussbericht(Hannover : Technische Informationsbibliothek (TIB), 2014) Dittrich, Barbara; Möller, MartinDie Entwicklung lokaler Drug-Delivery-Systeme im Rahmen des Verbundprojektes addressierte zwei häufige urologische Erkrankungen: die Überaktive Blase (OAB, overactive bladder) und das nicht-muskelinvasiven Blasenkarzinom (NMIBK). Die OAB besitzt mit einer Prävalenz von 17 % in den USA und Europa das Ausmaß einer Volkskrankheit. Aktuelle Ansätze zur intravesikalen lokalen Wirkstoffgabe beinhalten in der Regel die Einspülung von Wirkstofflösungen über einen Katheter in die Blase (Instillation). Hierbei werden z. B. Antimuskarinika gegen die Überaktive Blase (overactive bladder, OAB) oder ein Zytostatika zur Rezidiv- und Progressionsprophylaxe bei nicht-Muskel invasivem Blasenkarzinom (NMIBK) eingesetzt. Das Ziel des Teilvorhabens war die Entwicklung aktiver Mikrosphären und Filamente auf Polymerbasis zur lokalen Freisetzung von urologisch relevanten Wirkstoffen wie beispielsweise Trospiumchlorid oder Mitomycin C in die Blase. Durch die lokale Freisetzung sollen Nebenwirkungen, die bei einer systemischen Darreichung auftreten, vermieden bzw. minimiert werden. Es wurde ein skalierbares Herstellungsverfahren für die Herstellung der aktiven Mikrosphären entwickelt, ausgehend von der Mahlung und Dispersion der Wirkstoffpartikel in der Polymermatrix durch einen Naßmahlprozess, dem eigentlichen Herstellungsverfahren auf der Basis eines Emulsionsprozess und der anschließenden Aufarbeitung zu einem rieselfähigen Pulver durch das Verfahren der Sprühtrocknung. Das Freisetzungsverhalten der ausgewählten Polymermatrices wurde untersucht und eine Optimierung des Systems vorgenommen. Für die Indikation NMIBK wurde ein stark verkleinertes Filament-artiges Drug-Delivery-Systems entwickelt. Die entwickelten aktiven Mikrosphären konnten erfolgreich in das Gesamtsystem eingebaut werden und die entwickelten Drug-Delivery-Systeme wurden erfolgreich in den in-vitro und in-vivo Untersuchungen der Projektpartner angewendet.
- ItemCaLB Catalyzed Conversion of ε-Caprolactone in Aqueous Medium. Part 1: Immobilization of CaLB to Microgels(Basel : MDPI, 2016) Engel, Stefan; Höck, Heidi; Bocola, Marco; Keul, Helmut; Schwaneberg, Ulrich; Möller, MartinThe enzymatic ring-opening polymerization of lactones is a method of increasing interest for the synthesis of biodegradable and biocompatible polymers. In the past it was shown that immobilization of Candida antarctica lipase B (CaLB) and the reaction medium play an important role in the polymerization ability especially of medium ring size lactones like ε-caprolactone (ε-CL). We investigated a route for the preparation of compartmentalized microgels based on poly(glycidol) in which CaLB was immobilized to increase its esterification ability. To find the ideal environment for CaLB, we investigated the acceptable water concentration and the accessibility for the monomer in model polymerizations in toluene and analyzed the obtained oligomers/polymers by NMR and SEC. We observed a sufficient accessibility for ε-CL to a toluene like hydrophobic phase imitating a hydrophobic microgel. Comparing free CaLB and Novozym® 435 we found that not the monomer concentration but rather the solubility of the enzyme, as well as the water concentration, strongly influences the equilibrium of esterification and hydrolysis. On the basis of these investigations, microgels of different polarity were prepared and successfully loaded with CaLB by physical entrapment. By comparison of immobilized and free CaLB, we demonstrated an effect of the hydrophobicity of the microenvironment of CaLB on its enzymatic activity.
- ItemCellular responses to beating hydrogels to investigate mechanotransduction([London] : Nature Publishing Group UK, 2019) Chandorkar, Yashoda; Castro Nava, Arturo; Schweizerhof, Sjören; Van Dongen, Marcel; Haraszti, Tamás; Köhler, Jens; Zhang, Hang; Windoffer, Reinhard; Mourran, Ahmed; Möller, Martin; De Laporte, LauraCells feel the forces exerted on them by the surrounding extracellular matrix (ECM) environment and respond to them. While many cell fate processes are dictated by these forces, which are highly synchronized in space and time, abnormal force transduction is implicated in the progression of many diseases (muscular dystrophy, cancer). However, material platforms that enable transient, cyclic forces in vitro to recreate an in vivo-like scenario remain a challenge. Here, we report a hydrogel system that rapidly beats (actuates) with spatio-temporal control using a near infra-red light trigger. Small, user-defined mechanical forces (~nN) are exerted on cells growing on the hydrogel surface at frequencies up to 10 Hz, revealing insights into the effect of actuation on cell migration and the kinetics of reversible nuclear translocation of the mechanosensor protein myocardin related transcription factor A, depending on the actuation amplitude, duration and frequency.
- ItemComparison of Candida antarctica Lipase B Variants for Conversion of ε-Caprolactone in Aqueous Medium-Part 2(Basel : MDPI, 2018) Höck, Heidi; Engel, Stefan; Weingarten, Simone; Keul, Helmut; Schwaneberg, Ulrich; Möller, Martin; Bocola, MarcoEnzyme-catalyzed ring-opening polymerization of lactones is a method of increasing interest for the synthesis of polyesters. In the present work, we investigated which changes in the structure of Candida antarctica lipase B (CaLB) shift the catalytic equilibrium between esterification and hydrolysis towards polymerization. Therefore, we present two concepts: (i) removing the glycosylation of CaLB to increase the surface hydrophobicity; and (ii) introducing a hydrophobic lid adapted from Pseudomonas cepacia lipase (PsCL) to enhance the interaction of a growing polymer chain to the elongated lid helix. The deglycosylated CaLB (CaLB-degl) was successfully generated by site-saturation mutagenesis of asparagine 74. Furthermore, computational modeling showed that the introduction of a lid helix at position Ala148 was structurally feasible and the geometry of the active site remained intact. Via overlap extension PCR the lid was successfully inserted, and the variant was produced in large scale in Pichia pastoris with glycosylation (CaLB-lid) and without (CaLB-degl-lid). While the lid variants show a minor positive effect on the polymerization activity, CaLB-degl showed a clearly reduced hydrolytic and enhanced polymerization activity. Immobilization in a hydrophobic polyglycidol-based microgel intensified this effect such that a higher polymerization activity was achieved, compared to the “gold standard” Novozym® 435.
- ItemCubosomes from hierarchical self-assembly of poly(ionic liquid) block copolymers([London] : Nature Publishing Group UK, 2017) He, Hongkun; Rahimi, Khosrow; Zhong, Mingjiang; Mourran, Ahmed; Luebke, David R.; Nulwala, Hunaid B.; Möller, Martin; Matyjaszewski, KrzysztofCubosomes are micro- and nanoparticles with a bicontinuous cubic two-phase structure, reported for the self-assembly of low molecular weight surfactants, for example, lipids, but rarely formed by polymers. These objects are characterized by a maximum continuous interface and high interface to volume ratio, which makes them promising candidates for efficient adsorbents and host-guest applications. Here we demonstrate self-assembly to nanoscale cuboidal particles with a bicontinuous cubic structure by amphiphilic poly(ionic liquid) diblock copolymers, poly(acrylic acid)-block-poly(4-vinylbenzyl)-3-butyl imidazolium bis(trifluoromethylsulfonyl)imide, in a mixture of tetrahydrofuran and water under optimized conditions. Structure determining parameters include polymer composition and concentration, temperature, and the variation of the solvent mixture. The formation of the cubosomes can be explained by the hierarchical interactions of the constituent components. The lattice structure of the block copolymers can be transferred to the shape of the particle as it is common for atomic and molecular faceted crystals.
- ItemDesign–functionality relationships for adhesion/growth-regulatory galectins(Washington, DC : National Acad. of Sciences, 2019) Ludwig, Anna-Kristin; Michalak, Malwina; Xiao, Qi; Gilles, Ulrich; Medrano, Francisco J.; Ma, Hanyue; FitzGerald, Forrest G.; Hasley, William D.; Melendez-Davila, Adriel; Liu, Matthew; Rahimi, Khosrow; Kostina, Nina Yu; Rodriguez-Emmenegger, Cesar; Möller, Martin; Lindner, Ingo; Kaltner, Herbert; Cudic, Mare; Reusch, Dietmar; Kopitz, Jürgen; Romero, Antonio; Oscarson, Stefan; Klein, Michael L.; Gabius, Hans-Joachim; Percec, VirgilGlycan-lectin recognition is assumed to elicit its broad range of (patho)physiological functions via a combination of specific contact formation with generation of complexes of distinct signal-triggering topology on biomembranes. Faced with the challenge to understand why evolution has led to three particular modes of modular architecture for adhesion/growth-regulatory galectins in vertebrates, here we introduce protein engineering to enable design switches. The impact of changes is measured in assays on cell growth and on bridging fully synthetic nanovesicles (glycodendrimersomes) with a chemically programmable surface. Using the example of homodimeric galectin-1 and monomeric galectin-3, the mutual design conversion caused qualitative differences, i.e., from bridging effector to antagonist/from antagonist to growth inhibitor and vice versa. In addition to attaining proof-of-principle evidence for the hypothesis that chimera-type galectin-3 design makes functional antagonism possible, we underscore the value of versatile surface programming with a derivative of the pan-galectin ligand lactose. Aggregation assays with N,N′-diacetyllactosamine establishing a parasite-like surface signature revealed marked selectivity among the family of galectins and bridging potency of homodimers. These findings provide fundamental insights into design-functionality relationships of galectins. Moreover, our strategy generates the tools to identify biofunctional lattice formation on biomembranes and galectin-reagents with therapeutic potential.
- ItemEncapsulation of hydrophobic components in dendrimersomes and decoration of their surface with proteins and nucleic acids(Washington, DC : National Acad. of Sciences, 2019) Torre, Paola; Xiao, Qi; Buzzacchera, Irene; Sherman, Samuel E.; Rahimi, Khosrow; Kostina, Nina Yu.; Rodriguez-Emmenegger, Cesar; Möller, Martin; Wilson, Christopher J.; Klein, Michael L.; Good, Matthew C.; Percec, VirgilReconstructing the functions of living cells using nonnatural components is one of the great challenges of natural sciences. Compartmentalization, encapsulation, and surface decoration of globular assemblies, known as vesicles, represent key early steps in the reconstitution of synthetic cells. Here we report that vesicles self-assembled from amphiphilic Janus dendrimers, called dendrimersomes, encapsulate high concentrations of hydrophobic components and do so more efficiently than commercially available stealth liposomes assembled from phospholipid components. Multilayer onion-like dendrimersomes demonstrate a particularly high capacity for loading low-molecular weight compounds and even folded proteins. Coassembly of amphiphilic Janus dendrimers with metal-chelating ligands conjugated to amphiphilic Janus dendrimers generates dendrimersomes that selectively display folded proteins on their periphery in an oriented manner. A modular strategy for tethering nucleic acids to the surface of dendrimersomes is also demonstrated. These findings augment the functional capabilities of dendrimersomes to serve as versatile biological membrane mimics.
- ItemEnumerative Geometry of Surfaces (hybrid meeting)(Zürich : EMS Publ. House, 2021) Grushevsky, Samuel; Möller, MartinThe recent developments in hyperbolic geometry and flat geometry in real dimension $2$ formed the core of the workshop, with an emphasis on enumerative aspects. A particularly important role in this regard was played by intersection-theoretic techniques on $\overline{\mathcal{M}}_{g,n}$, the geometry of the strata of differentials, the geometry of Hurwitz spaces, topological recursion techniques, and large genus asymptotics. The workshop included an exploration of relations with similar problems in complex dimension $2$, tropical techniques for enumerative problems, and relations to mathematical physics.
- ItemExploring functional pairing between surface glycoconjugates and human galectins using programmable glycodendrimersomes(Washington, DC : National Acad. of Sciences, 2018) Xiao, Qi; Ludwig, Anna-Kristin; Romanò, Cecilia; Buzzacchera, Irene; Sherman, Samuel E.; Vetro, Maria; Vértesy, Sabine; Kaltner, Herbert; Reed, Ellen H.; Möller, Martin; Wilson, Christopher J.; Hammer, Daniel A.; Oscarson, Stefan; Klein, Michael L.; Gabius, Hans-Joachim; Percec, VirgilPrecise translation of glycan-encoded information into cellular activity depends critically on highly specific functional pairing between glycans and their human lectin counter receptors. Sulfoglycolipids, such as sulfatides, are important glycolipid components of the biological membranes found in the nervous and immune systems. The optimal molecular and spatial design aspects of sulfated and nonsulfated glycans with high specificity for lectin-mediated bridging are unknown. To elucidate how different molecular and spatial aspects combine to ensure the high specificity of lectin-mediated bridging, a bottom-up toolbox is devised. To this end, negatively surface-charged glycodendrimersomes (GDSs), of different nanoscale dimensions, containing sulfo-lactose groups are self-assembled in buffer from a synthetic sulfatide mimic: Janus glycodendrimer (JGD) containing a 3′-O-sulfo-lactose headgroup. Also prepared for comparative analysis are GDSs with nonsulfated lactose, a common epitope of human membranes. These self-assembled GDSs are employed in aggregation assays with 15 galectins, comprising disease-related human galectins, and other natural and engineered variants from four families, having homodimeric, heterodimeric, and chimera architectures. There are pronounced differences in aggregation capacity between human homodimeric and heterodimeric galectins, and also with respect to their responsiveness to the charge of carbohydrate-derived ligand. Assays reveal strong differential impact of ligand surface charge and density, as well as lectin concentration and structure, on the extent of surface cross-linking. These findings demonstrate how synthetic JGD-headgroup tailoring teamed with protein engineering and network assays can help explain how molecular matchmaking operates in the cellular context of glycan and lectin complexity.
- ItemFlat Surfaces and Algebraic Curves(Zürich : EMS Publ. House, 2018) Möller, Martin; Zorich, AntonThis workshop brought together two distinct communities: “flat” geometers, studying the moduli of flat surfaces, and Teichmüller dynamics, and algebraic geometers studying the moduli space of curves. While both communities study similar or often the same objects, very different viewpoints and toolboxes lead to different questions being addressed, and different progress being made. The workshop sought to educate each community about the techniques of the other, and to foster communication between the two groups. One particular focus was enumerative geometry.
- ItemFlat Surfaces and Dynamics on Moduli Space(Zürich : EMS Publ. House, 2014) Möller, Martin; Zorich, AntonDynamics of the Teichmüller geodesic flow on the moduli space of curves and asymptotic monodromy of the Hodge bundle along this flow have numerous applications to dynamics and geometry of measured foliations, to billiards in polygons, to interval exchange transformations, and to geometry of flat surfaces.
- ItemFormaldehyde-free curing of cotton cellulose fabrics in anhydrous media(New York, NY : Wiley, 2020) Mommer, Stefan; Kurniadi, Juliana; Keul, Helmut; Möller, MartinThe effect of formaldehyde-free curing on standard cotton cellulose fabrics in anhydrous media is studied. Different crosslinkers are applied via (1) a pad-cure-dry process (solid/liquid) and (2) in a vapor chamber (solid/gas). The performance of each crosslinker and set of conditions is assessed by measuring dry crease recovery angles, DCRAs. We find that in control samples (treatment without crosslinker) the DCRAs are altered depending on the solvent. Using DMF, carbonyldiimidazole shows the best DCRA (160.1°, 15° higher than the non-treated fabrics). In ethyl acetate, triglycidyl isocyanurate shows the highest DCRA (22° higher than the control). The most promising crosslinkers are applied with selected catalysts known from literature. Here, trigycidyl isocyanurate in combination with the superbase P4-t-Bu gives the best DCRA (35° higher than the control). Using the vapor-chemical finishing, divinylsulfone as crosslinker increases the DCRA to 162.7° (18° higher than non-treated fabrics). Hence, cotton cellulose fabrics can be successfully finished in anhydrous conditions. © 2019 The Authors. Journal of Applied Polymer Science published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48371. © 2019 The Authors. Journal of Applied Polymer Science published by Wiley Periodicals, Inc.
- ItemGuidance of mesenchymal stem cells on fibronectin structured hydrogel films(San Francisco, California, US : PLOS, 2014) Kasten, Annika; Naser, Tamara; Brüllhoff, Kristina; Fiedler, Jörg; Müller, Petra; Möller, Martin; Rychly, Joachim; Groll, Jürgen; Brenner, Rolf E.; Engler, Adam J.Designing of implant surfaces using a suitable ligand for cell adhesion to stimulate specific biological responses of stem cells will boost the application of regenerative implants. For example, materials that facilitate rapid and guided migration of stem cells would promote tissue regeneration. When seeded on fibronectin (FN) that was homogeneously immmobilized to NCO-sP(EO-stat-PO), which otherwise prevents protein binding and cell adhesion, human mesenchymal stem cells (MSC) revealed a faster migration, increased spreading and a more rapid organization of different cellular components for cell adhesion on fibronectin than on a glass surface. To further explore, how a structural organization of FN controls the behavior of MSC, adhesive lines of FN with varying width between 10 µm and 80 µm and spacings between 5 µm and 20 µm that did not allow cell adhesion were generated. In dependance on both line width and gaps, cells formed adjacent cell contacts, were individually organized in lines, or bridged the lines. With decreasing sizes of FN lines, speed and directionality of cell migration increased, which correlated with organization of the actin cytoskeleton, size and shape of the nuclei as well as of focal adhesions. Together, defined FN lines and gaps enabled a fine tuning of the structural organization of cellular components and migration. Microstructured adhesive substrates can mimic the extracellular matrix in vivo and stimulate cellular mechanisms which play a role in tissue regeneration.
- ItemHigh-Throughput Production of Micrometer Sized Double Emulsions and Microgel Capsules in Parallelized 3D Printed Microfluidic Devices(Basel : MDPI, 2019) Jans, Alexander; Lölsberg, Jonas; Omidinia-Anarkoli, Abdolrahman; Viermann, Robin; Möller, Martin; De Laporte, Laura; Wessling, Matthias; Kuehne, Alexander J. C.Double emulsions are useful geometries as templates for core-shell particles, hollow sphere capsules, and for the production of biomedical delivery vehicles. In microfluidics, two approaches are currently being pursued for the preparation of microfluidic double emulsion devices. The first approach utilizes soft lithography, where many identical double-flow-focusing channel geometries are produced in a hydrophobic silicone matrix. This technique requires selective surface modification of the respective channel sections to facilitate alternating wetting conditions of the channel walls to obtain monodisperse double emulsion droplets. The second technique relies on tapered glass capillaries, which are coaxially aligned, so that double emulsions are produced after flow focusing of two co-flowing streams. This technique does not require surface modification of the capillaries, as only the continuous phase is in contact with the emulsifying orifice; however, these devices cannot be fabricated in a reproducible manner, which results in polydisperse double emulsion droplets, if these capillary devices were to be parallelized. Here, we present 3D printing as a means to generate four identical and parallelized capillary device architectures, which produce monodisperse double emulsions with droplet diameters in the range of 500 µm. We demonstrate high throughput synthesis of W/O/W and O/W/O double emulsions, without the need for time-consuming surface treatment of the 3D printed microfluidic device architecture. Finally, we show that we can apply this device platform to generate hollow sphere microgels.
- ItemHomoserine Lactone as a Structural Key Element for the Synthesis of Multifunctional Polymers(Basel : MDPI, 2017) Marquardt, Fabian; Mommer, Stefan; Lange, Justin; Jeschenko, Pascal M.; Keul, Helmut; Möller, MartinThe use of bio-based building blocks for polymer synthesis represents a milestone on the way to “green” materials. In this work, two synthetic strategies for the preparation of multifunctional polymers are presented in which the key element is the functionality of homoserine lactone. First, the synthesis of a bis cyclic coupler based on a thiolactone and homoserine lactone is displayed. This coupler was evaluated regarding its regioselectivity upon reaction with amines and used in the preparation of multifunctional polymeric building blocks by reaction with diamines. Furthermore, a linear polyglycidol was functionalized with homoserine lactone. The resulting polyethers with lactone groups in the side chain were converted to cationic polymers by reaction with 3-(dimethylamino)-1-propylamine followed by quaternization with methyl iodide.
- ItemHybrid nanostructured particles via surfactant-free double miniemulsion polymerization([London] : Nature Publishing Group UK, 2018) Zhao, Yongliang; Liu, Junli; Chen, Zhi; Zhu, Xiaomin; Möller, MartinDouble emulsions are complex fluid systems, in which droplets of a dispersed liquid phase contain even smaller dispersed liquid droplets. Particularly, water-in-oil-in-water double emulsions provide significant advantages over simple oil-in-water emulsions for microencapsulation, such as carrier of both aqueous and oily payloads and sustained release profile. However, double emulsions are thermodynamically unstable systems consisting typically of relatively large droplets. Here we show that nanoscale water-in-oil-in-water double emulsions can be prepared by adding a silica precursor polymer, hyperbranched polyethoxysiloxane, to the oil phase without any additional surfactants. The resulting double miniemulsions are transformed to robust water@SiO2@polymer@SiO2 nanocapsules via conversion of the precursor to silica and polymerization of the oil phase. Other intriguing nanostructures like nanorattles and Janus-like nanomushrooms can also be obtained by changing preparation conditions. This simple surfactant-free double miniemulsion polymerization technique opens a promising avenue for mass production of various complex hybrid nanostructures that are amenable to numerous applications.
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