Прищеплені полімерні щітки на мінеральних поверхнях, чутливі до дії зовнішніх чинників

Abstract

Дисертацію присвячено розробці стратегії синтезу та одержанню нових полімерних матеріалів – прищеплених полімерних щіток, які чутливі до дії зовнішніх чинників. Такі матеріали здатні змінювати свої властивості при відносно невеликих змінах температури чи рН. Це відкриває нові можливості для створення матеріалів для розвитку клітинної інженерії, біотехнології, наномедицини, у якості засобів доставки лікарських засобів, діагностики захворювань тощо. Диссертация посвящена разработке стратегии синтеза и получения новых полимерных материалов – привитых полимерных щеток чувствительных к действию внешних факторов. Эти материалы меняют свои свойства при относительно небольших изменениях температуры или рН. Это открывает возможности для создания материалов для развития клеточной инженерии, биотехнологии, наномедицины, средств доставки лекарских препаратов, диагностирования заболеваний и другие. The dissertation is devoted to the development of a strategy for the synthesis and production of new polymeric materials – grafted polymer brushes, which are sensitive to external stimuli. Such materials are able to change their properties upon small temperature or pH changes. For this purpose, first APTES and multifunctional initiators (MI) coatings on the glass surfaces were fabricated. We used two types of MI that are able to initiate graft polymerization from the surface (multifunctional peroxide initiators (MPI) and ATRP initiators); at the same time they contain functional groups that are responsible for grafting to the surface. In addition, some MI studied by us contain special purpose groups that give the surface certain functions, such as the orientation of liquid crystals or pH-sensitivity. Then, temperature-responsive grafted polymer brushes based on N-isopropylacrylamide, oligo(ethylene glycol) methacrylate (OEGMA), 4-vinylpyridine (4VP), butyl methacrylate (BMA), butyl acrylate (BA), pentaerythritol monomethacrylate or cholesteryl methacrylate (PChMa) were fabricated and their properties were comprehensively studied. In addition, the grafted brushes of P(4VP-co-OEGMA) were fabricated and characterized, their properties were compared with grafted brushes of P4VP and POEGMA. It was shown that at certain ratios of 4VP and OEGMA fragments in the grafted brushes, the obtained nanocoatings show two lower critical solution temperature (LCST). The temperature-responsive grafted polymer brushes with LCST were used as polymer matrices for the formation of silver nanoparticles (Ag-NPs). The influence of the chemical nature of the polymer brush on the shape, size and amount of Ag-NPs is proved. The antibacterial properties of nanocoatings of grafted polymer brushes POEGMA and P4VP with embedded Ag-NP in relation to Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923 were investigated by serial dilution with a 12-hour incubation period of 4 °C and 37 °C, lower and higher than LCST. At 4 °C, there is no significant difference between the amounts of bacteria recorded on the surfaces of the nanocoatings of grafted POEGMA brushes and with incorporated Ag-NPs. At the same time, at 37 °C we do not observe bacterial growth on the surface of POEGMA nanocoatings with embedded Ag-NPs, while bacterial growth remains unchanged on "pure" POEGMA nanocoatings at both temperatures, which indicates a strong dependence of antibacterial properties on temperature for POEGMA brushes with embedded Ag-NPs. The results obtained for bacteria seeded on polymer nanocoatings based on P4VP are similar. The properties of nanocoatings of temperature-responsive grafted polymer brushes with a temperature transition according to the melting temperature principle were investigated. Grafted PBMA and PBA brushes were synthesized; their physicochemical properties and temperature-responsive changes in surface morphology and wetting contact angles were studied. For the first time, the adsorption of protein on the surface modified by nanocoatings of grafted PBMA and PBA brushes is studied. The temperature dependence of adsorption was shown, which almost doubles with increasing temperature for PBMA nanocoatings. In contrast to PBMA nanocoatings, for PBA brushes intensity of protein adsorption showed almost no temperature dependence. The nanocoatings of temperature-responsive grafted liquid crystal polymer brushes were fabricated. It was found that the transition temperatures for grafted PChMa brushes are shifted to lower temperatures compared to free macromolecules of the same polymer, due to a decrease in the number of degrees of freedom in the grafted polymer brushes. The first temperature-induced transition, which is observed for temperatures from 5 to 25 °C, was well expressed in the analysis of the contact angle of wetting and weaker, but clearly visible in the analysis of DSC and AFM, indicates a horizontal adjustment in the structure of nanocoatings grafted brushes PChMa, and may be associated with the phenomenon of β-relaxation in the vitreous state. The second temperature-induced transition was associated with the transition from vitreous to viscous state of the polymer, well expressed in the measurements of DSC and AFM. The temperature- or pH-sensitive grafted polymer brushes were successfully synthesized by initiated polymerization from peroxide groups MPI pre-immobilized on the surface of boron nitride nanotubes (BNNTs). The proposed method of preparation of responsive BNNTs has at least two advantages. First, functionalized BNNTs are well dispersed in water and have a responsive properties at physiological temperatures. Second, the chemical structure of BNNTs changes slightly due to their modification of MPI due to the interaction of amino groups (defects) of BNNT with chloroanhydride groups of MPI. In addition, each covalently grafted molecule MPI contains several centers of initiation of the grafted polymerization. Fabrication of the stimuli-responsive grafted polymer brushes on the surfaces of inorganic materials opens up new opportunities for the creation of materials for the development of cell engineering, biotechnology, nanomedicine, as a means of drug delivery, disease diagnosis and more.