Project Number: 2020/37/N/ST4/01991
Project implemented as part of the PRELUDIUM 19 programme
Title of the project: Synthesis of troxerutin-inspired brush-shaped polymers through ATRP methods with diminished catalyst concentration
Principal Investigator: Izabela Zaborniak, MSc, Eng.
Project supervisor: Prof. Dr. Paweł Chmielarz, DSc, PhD, Eng.
Project Value: 209 999 PLN
Financing with resources of National Science Centre, Poland
Aim of the Project:
Atom transfer radical polymerization (ATRP) is a process belonging to the versatile reversibledeactivation radical polymerization (RDRP) procedures. The essence of ATRP is formation of an equilibrium between a low concentration propagating radicals and a larger number of dormant species. Compared to conventional free radical polymerization the step of radical generation is reversible and occurs by a dynamic redox mechanism. Furthermore, polymers and biopolymers prepared by ATRP are characterized by narrow molecular weight distributions (MWDs) and control over molecular weights (MWs). Moreover it allows site incorporation of functionalities and preparation of well-defined hybrid composites. This technique has had a significant impact on the development of various branches in biotechnology, mostly because of its extensive applications in the preparation of biomaterials based on polymers. The use of ATRP makes it possible to control polymer topology and obtain various structures, ranging from linear chains, stars, cycles, combs and brushes, up to regular networks. This technique also allows preparation of polymers with controlled composition such as block, graft, gradient and periodic copolymers. The main disadvantage of the initially developed “normal” ATRP was the use of a relatively high concentration of catalyst, often between 1000-10000 ppm, calculated as the molar ratio of catalyst complex to monomer. Consequently, extensive purification was required, which generates higher process costs for the products. Initially, a high concentration of activator complex was necessary to overcome the increase in concentration of deactivator due to the termination reactions, which led to a slow-down in the rate of the reaction. This problem was resolved by the development of new ATRP methods based on activator regeneration, which allow for significantly diminished concentrations of the catalyst, down to 100 ppm or less. In these methods creation of an additional redox cycle regenerates the activator by reduction of the deactivator. The headline aim of the research project is the optimization of the synthesis of novel naturally-derived stimuli-responsive polymer brushes using low ppm ATRP techniques based on continuous regeneration of catalyst complex, starting from supplemental activation reducing agent (SARA) ATRP utilizing copper as a reducing agent in organic solvent, moving to more environmentally friendly reaction medium – miniemulsion, using activator regeneration by electron transfer (ARGET) ATRP and external stimuli to regenerate catalytic complex, including ultrasonication-induced ATRP (sono-ATRP) in which, under the ultrasonic waves in the aqueous environment, hydroxyl radicals are created constituting the factor leading to the regeneration of Cu (I), without necessity of introducing any additional chemical compound making this technique extremely pure in context to current art of state in low ppm ATRP techniques. The realisation of the project in particular relies on kinetic analysis of the electrochemical catalytic process (EC’) during reduction of the regenerated CuIIBr2/TPMA in the presence of the received ATRP troxerutin-based macroinitiator (Trox-Br10) and subsequently detailed cognition of mechanism and kinetics of polymerization processes with the use of that brominated macromolecule. An another significant aspect of the research is also particular comprehension of the mechanism and kinetics of ATRP syntheses determining the reaction rate constants of particular partial reactions and investigation of chemical structure of the obtained polymer brushes. In connection with the innovation nature of the synthesized biopolymer and also providing novel information related to mechanism and kinetics of conducted reactions, the realisation of the presented project will certainly lead to development of important scientific domain such as Polymer, Biopolymer Chemistry being a part of the domain of scientific research ST - Science and Technology. It is assumed that these troxerutin-based brushes will be ensure flow control of substances in and out in connection to significant pH response due to anionic poly(acrylic acid) (PAA) segments and cationic poly(2-dimethylaminoethyl methacrylate) side chains, additionally the macromolecules are nonimmunogenic, nontoxic and biocompatible, which undoubtedly allow for wide potential application in medicine as stimuli-sensitive drug carriers. Taking into account the fact that troxerutin is used as a vasoprotective, this modified structure can improve its activity or be a carrier for this structure.
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