Polymer Chemistry @ University of Glasgow
Our group is working on four different topics in synthetic polymer science:
- Hydrophilic polymers for self-assembly and phase separations
- Polymer/Metal-organic framework hybrid materials
- Carbon Nitride in polymer chemistry
- Lignin-based polymer materials
We mainly work with reversible deactivation radical polymerization techniques as well as modular ligation reactions and photochemistry for the development of novel materials.
Hydrophilic Polymers for Self-Assembly and Phase Separations
Hydrophilic polymers play an important role in modern polymer science and technology, for example in drug-delivery, cosmetics, food and biomaterials. Especially, block copolymers turned to be compounds in these applications. Frequently amphiphilic block copolymers that feature a hydrophobic and a hydrophilic part are utilized in that regard. Nevertheless, their biocompatibility and permeability for molecules are hindered, which hamper the use for some applications.
An approach to the solution of these problems and an extension of polymeric drug delivery agents towards more complex drugs is investigated in our group. We study the self-assembly behavior of double hydrophilic block copolymers (DHBC) in aqueous solution. Our main aim is to form these polymers from non-toxic biocompatible building blocks. The formed self-assemblies will have significantly different permeability profiles compared to state-of-the-art amphiphilic block copolymers especially for novel types of drugs and other carriers, e.g. proteins or nanogels. The development of DHBC-based encapsulation systems will open a new field in polymeric drug-delivery and enzyme catalysis environment. The combination with enzyme catalysis leads to novel nanoreactors that might be useful for enzyme therapy. Moreover, we investigate novel crosslinking methods for the formed self-assemblies as well as their microstructure.
In addition to DHBCs, we also investigate aqueous multi-phase systems formed from water-soluble homopolymers. As such, completely water-based multi-phase systems can be generated, e.g. from poly(ethylene glycol) and dextran. In a further step, we introduce stabilizers to fabricate water-in-water emulsions without any hydrophobic barrier. These multi-phase systems can be utilized as environment for enzymatic catalysis or as precursors for multi compartment hydrogels. We envision applications for example in the fields of cell engineering, drug-delivery, food or cosmetics.
Check out these Publications:
Bernhard V. K. J. Schmidt:* Double-hydrophilic block copolymer self-assembly in aqueous solution, Macromolecular Chemistry and Physics 2018, 219 (7),1700494.
Marko Pavlovic, Alexander Plucinski, Jianrui Zhang, Markus Antonietti, Lukas Zeininger,* Bernhard V. K. J. Schmidt:* Cascade kinetics in an enzyme-loaded aqueous two-phase system, Langmuir 2020, 36 (6), 1401-1408.
Jianrui Zhang, Jongkook Hwang, Markus Antonietti, Bernhard V. K. J. Schmidt:* Water-in-water Pickering emulsion stabilized by polydopamine particles, Biomacromolecules 2019, 20 (1), 204-211.
Noah Al-Nakeeb, Jochen Willersinn, Bernhard V. K. J. Schmidt:* Self-Assembly Behavior and Biocompatible Crosslinking of Double Hydrophilic Linear-Brush Block Copolymers, Biomacromolecules 2017, 18 (11), 3695-3705.
Jochen Willersinn, Anna Bogomolova, Marc Brunet Cabré, Bernhard V. K. J. Schmidt:* Vesicles of double hydrophilic pullulan and poly(acrylamide) block copolymers: A combination of synthetic- and bio-derived blocks, Polymer Chemistry 2017, 8, 1244-1254.
Polymer/Metal-organic Framework Hybrid Materials
Metal-organic frameworks (MOFs) belong to the most promising materials at the moment. Due to their well-defined structure and high porosity, several highly relevant applications are discussed, e.g. gas storage, catalysis or energy storage, just to name a few. MOFs are formed from metal-ions and multi functional ligands and variation in these components allows the introduction of tailored materials properties, like pore size or pore chemistry.
Reversible deactivation radical polymerization techniques have attracted significant attention in polymer sciences as well as materials sciences. Thus, molecular weight, polydispersity and endgroups can be controlled easily. Nevertheless, control over monomer sequence and stereochemistry is still not reached. Although several methods exist in that regard, a convenient method has not been described so far. A solution for that issue might lie in porous materials. The research on porous materials has led to variety of accessible compounds with well-defined pore sizes and geometries. Kitagawa and Uemura showed that polymerization reactions can be conducted inside of MOF materials with enhanced stereocontrol. From these encouraging results we are looking for novel systems to increase the control of polymer tacticity.
In addition to being a suitable environment for polymerizations, MOFs can be utilized as polymerization catalysts as well. In recent years, we utilized copper-based MOFs in ATRP as heterogeneous (photo)catalyst. The catalyst proved to be recyclable and less catalyst contamination was found in the polymer products after purification, compared to common methods. Moreover, monomers could be polymerized that are usually inaccessible via ATRP. Overall, MOF polymerization catalysis comprises several advantages over traditional homogeneous catalysts and might be an alternative for the future.
The control over MOF morphology is one of the emerging areas in MOF research. For example, in our group we investigated is the morphosynthesis of metal-organic mesocrystals based on a combination of metal-organic framework synthesis and double hydrophilic block copolymers. In such a way unprecedented crystal architectures were generated easily. In addition, we investigated other additives to control MOF morphology, e.g. solvents or acids. In such a way, control over MOF crystal shapes is enabled that gives rise to advancements in applications like gas storage/filtering, catalysis or energy storage.
Check out these Publications:
Bernhard V. K. J. Schmidt* Metal-organic frameworks in polymer science: Polymerization catalysis, polymerization environment and hybrid materials, Macromolecular Rapid Communications 2020, 41 (1), 1900333.
Jongkook Hwang, Tobias Heil, Markus Antonietti, Bernhard V. K. J. Schmidt:* Morphogenesis of Metal-Organic Mesocrystals Mediated by Double Hydrophilic Block Copolymers, Journal of the American Chemical Society 2018, 140 (8), 2947-2956.
Jongkook Hwang, Hui-Chun Lee, Markus Antonietti, Bernhard V. K. J. Schmidt:* Tacticity Controlled Poly(vinyl alcohol) and Multitactic Block Copolymers via Metal-Organic-Framework Confined Polymerization, Polymer Chemistry 2017, 8 (40), 6204-6208.
Hui-Chun Lee, Marco Fantin, Markus Antonietti,* Krzysztof Matyjaszewski,* Bernhard V. K. J. Schmidt:* Synergic Effect between Nucleophilic Monomers and Cu(II)-Metal-Organic Framework for Visible Light-Triggered Controlled Photopolymerization, Chemistry of Materials 2017, 29 (21), 9445–9455.
Hui-Chun Lee, Tobias Heil, Jian-Ke Sun,* Bernhard V. K. J. Schmidt:* Dispersion of Nano-MOFs via a Stimuli-Responsive Biohybrid System with Enhanced Photocatalytic Performance, Materials Horizons 2019, 6, 802-809.
Carbon Nitride in Polymer Chemistry
Carbon nitride (CN) is well-known for its photocatalytic properties that are triggered by visible light. It is used as catalyst in hydrogen evolution, carbon dioxide reduction or organic transformations. The properties of CN can be tailored by precursor composition to install specific porosity, light absorption or functionality.
In our research we utilize CN as photoinitiator for the formation of hydrogels and via visible light. Moreover, CN acts as a reinforcer and crosslinker at the same time, which leads to hydrogels with remarkable mechanical properties, e.g. against compression and shear forces. Depending on CN content, monomer composition and CN functionality, a plethora of mechanical properties can be designed. Furthermore, the photo-initiated polymerization allows the formation of hydrogel materials with spatial control, e.g. via utilization of photomasks. Due to CN incorporation the hydrogels feature photocatalytic properties, e.g. in hydrogen evolution. Currently, we are developing novel hydrogel formulations to vary mechanical properties and compositions with the goal of mimicking the mechanical properties of biological tissues and fabrication of tailor-made soft materials. In a similar way, CN can be used as photoinitiator for common polymerizations in solution or emulsion.
One of the great challenges in CN research is the low dispersibility that hampers easy processing. In order to tackle that problem, we work on new avenues to functionalize CN for example with polymers or small molecules. Such functionalization enables enhanced dispersibility and processing via methods such as dip coating, spin coating or even inkjet printing.
Check out these Publications:
Qian Cao, Baris Kumru, Markus Antonietti, Bernhard V.K.J. Schmidt* Graphitic Carbon Nitride and Polymers: A Mutual Combination for Advanced Properties, Materials Horizons 2020, 7, 762-786.
Baris Kumru, Menny Shalom,* Markus Antonietti, Bernhard V. K. J. Schmidt:* Reinforced Hydrogels via Carbon-Nitride Initiated Polymerization, Macromolecules 2017, 50 (5), 1862-1869.
Baris Kumru, Markus Antonietti, Bernhard V. K. J. Schmidt:* Enhanced Dispersibility of Graphitic Carbon Nitride Particles in Aqueous and Organic Media via a One Pot Grafting Approach, Langmuir 2017, 33, 9897-9906.
Baris Kumru, Jesus Barrio, Jianrui Zhang, Markus Antonietti, Menny Shalom,* Bernhard V. K. J. Schmidt:* Robust Carbon-Nitride based Thermoset Coatings for Surface Modification and Photochemistry, ACS Applied Materials and Interfaces 2019, 11, 9462-9469.
Qian Cao, Tobias Heil, Baris Kumru, Markus Antonietti, Bernhard V. K. J. Schmidt:* Visible-light induced emulsion photopolymerization with carbon nitride as stabilizer and photoinitiator, Polymer Chemistry 2019, 10 (39), 5315-5323.
Qian Cao, Baris Kumru, Markus Antonietti, Bernhard V. K. J. Schmidt:* Grafting Polymers onto Carbon Nitride via Visible Light Induced Photofunctionalization, Macromolecules 2019, 52 (13), 4989-4996.
Lignin-based Polymer Materials
The depletion of fossil fuels has led to the utilization of a variety of renewable feedstocks in chemistry. Thus a sustainable way towards fuels, chemicals and other materials is under investigation. One particular interesting feedstock is lignin that is a polyphenol usually found in plants and constitutes around 30% of the non-fossil organic carbon. At the moment most of the lignin ‑ a byproduct of paper production ‑ is wasted and used as fuel. In our research, we utilize hydro/solvothermal treated lignocellulosic biomass in the formation of polymeric/oligomeric materials. We aim for novel biobased surfactants and various polymer materials, e.g. polycarbonates, polyesters or polyacrylates.
Check out these Publications:
Bernhard V. K. J. Schmidt,* Valerio Molinari, Davide Esposito, Klaus Tauer, Markus Antonietti: Lignin-derived polymeric surfactants for emulsion polymerization of styrene, Polymer 2017, 112, 418-426.
Majd Al-Naji,* Begoña Puértolas, Baris Kumru, Daniel Cruz, Marius Bäumel, Bernhard V. K. J. Schmidt, Nadezda V. Tarakina, Javier Pérez‐Ramírez: Sustainable Continuous Flow Valorization of γ-Valerolactone with Trioxane to α-Methylene-γ-Valerolactone over Basic Beta Zeolite, ChemSusChem 2019,12 (12), 2628-2636.