We employ modern polymerization methods and versatile polymer postmodification reactions to build up complex, yet defined polymer structures. We use all the established methods of polymerization, however, controlled radical polymerization as ATRP and RAFT, often in combination with click reactions are the most frequently used techniques.
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Some polymer exhibits a lower critical solution temperature (LCST) and some an upper critical solution temperature (UCST) type behavior in aqueous solutions. The thermoresponsive properties are influenced by several factors, such as concentration, molecular weight, presence of salts, and branching of the polymer. Besides thermoresponsive property numerous polymers exist, which respond to other stimulus such as light, pH, redox, etc. The development of modern polymerization, new modification and functionalization methods has enabled also the preparation of systems, which respond to multible changes in the environment. Polymers and Colloids Research Group developes new polymer architectures and studies their responsive behaviors in various environments.
The applications of responsive polymers include systems for drug-delivery, smart coatings, hydrogels, sensors, bioconjugates and degradable materials.
Water-soluble graft copolymers are one of the promising carrier materials for drug delivery applications. Especially graft copolymers with polysaccharide backbones are desirable due to their biocompatibility, biodegradability and unique bioactivity. Hyaluronic acid is a naturally occurring polysaccharide and a main constituent of the vitreous humour. Our approach utilizes a high molecular weight hyaluronic acid backbone, which is grafted with shorter side chains. The multifunctional polyether consists of a polyethylene glycol backbone and 1,2-diol moieties in every repeating unit that can be functionalized with variety of drugs, probes and targeting ligands. The water-soluble graft copolymer is intended as a delivery vehicle for sustained intravitreal drug delivery.
Silicon-based mesoporous nanoparticles have been extensively studied to meet the challenges in the drug delivery. Nanoparticles’ drug loading capacity, colloidal stability, and interactions with loaded drugs are related to their physico-chemical properties and are important for a functional drug delivery device. The ability to gain information from the inner structure of particle is especially interesting in case of mesoporous nanoparticles. We compare the morphology, porosity, and size of silicon-based mesoporous nanoparticles by combining dry-state techniques like transmission electron microscope to the multiangular light scattering techniques.
The most often utilized method to prepare polymer colloids is emulsion polymerization where a monomer is polymerized via a free radical polymerization process in an aqueous medium in the presence of a stabilizer system. Other two variations are the microemulsion and miniemulsion polymerization processes which are used to prepare submicron-size polymer colloids. These techniques are utilized in creating various nano and micro sized particles with potential applications in catalysis and as carriers for active substances. Recently we have started to study also the polymerization induced self-assembling (PISA) processes.
Modern synthetic methods have made it relatively easy to construct nanoscaled hydrid materials, which combine inorganic and organic substances or synthetic and biological matter. Examples vary from inorganic entities as gold, silver, copper, silica nanoparticles grafted with synthetic polymers to polymeric bioconjugates. What comes to the latter example, hyaluronic acid (HA) is one of the interesting biopolymers. We have synthesized both graft and block copolymers based on HA.
The use of biopolymers extracted from the biomass as an alternative to synthetic polymers is one important way of utilizing biomass. In addition to using biopolymers in their native forms, the properties of biopolymers can be altered by modification (chemical, physical, enzymatic) of the polymeric chains. Our group focuses on the macromolecular characterization of chemically modified hemicelluloses and chemically modified cellulose. Cellulose nanofibers with polycations by interfacial polyelectrolyte complexation is demonstrated. The used fiber preparation is expected to open up new avenues in the application of nanocelluloses in advanced fibrous materials, crimping, and responsive smart textiles. Of biosynthesized fibers, spider silk has inspired multiple works for novel, tough and strong fibers, due to its excellent mechanical properties albeit being processed in aqueous and ambient conditions at near neutral pH.
Polymers and Colloids Researchers develop new complicated polymer architectures to be utilized in special applications. The group has excellent control of the most important structure and property characterization methods of polymers. Besides the thorough chemical analysis of the prepared products, studies on supramolecular gelation, nanoparticle formation, morphological features, thermal stability and mechanical properties are conducted using spectroscopic, scattering, and rheological methods. The most important instruments in constant use include NMR, fluorescence, and circular dichroism spectrometers, light scattering, size exclusion chromatographs, an asymmetric flow field flow fractionation system (AF4), rheometers, a dynamic mechanical analyser, a conventional DSC and a microcalorimeter.