Hybrid Materials: Surface Modification of Different Silica Surfaces and Synthesis of Multiresponsive Hybrid Polymers

by Mikko Karesoja

Institution: University of Helsinki
Department: Department of Chemistry, Laboratory of Polymer Chemistry
Year: 2015
Keywords: polymeerikemia
Record ID: 1141173
Full text PDF: http://hdl.handle.net/10138/144501


In this study several inorganic-organic hybrids and multiresponsive hybrid polymers were prepared and characterised in detail. Especially the focus has been on stimuli responsive materials but also on nanocomposites based on modified montmorillonite clay. Furthermore thin SiO2-capillaries were modified for electrophoretic separations. In all cases different controlled radical polymerisation techniques have been used. The modification of montmorillonite clay was conducted by surface initiated atom transfer polymerisation. Clay was grafted with random copolymer of butyl acrylate and methyl methacrylate and the modified clay was further mixed with a matrix polymer with the same chemical composition to create nanocomposite films. The relation of the nanocomposite structure to its mechanical properties was in the main focus. The extent of exfoliation of the clay in the composite films clearly affected mechanical properties. Montmorillonite clay was also grafted with pH- and thermoresponsive poly(2-dimethylaminoethyl methacrylate). The thermoresponsive properties of the resulting hybrid materials were compared to similar homopolymer. The inner walls of thin silica capillaries were grafted with a cationic polymer, poly([2-(methacryloyl)oxyethyl]trimethylammonium chloride) (PMOTAC). These capillaries were further used in capillary electrophoresis to separate standard proteins, different β-blockers and low-density as well as high density lipoproteins. The separation of the analytes was not possible with bare SiO2-capillaries but with polymer coated capillaries good separation of the analytes was achieved. Hybrid materials based on mesoporous silica particles grafted with poly(N-vinylcaprolactam-b-polyethylene oxide) (PVCL-b-PEO) were synthesised. The challenging synthesis of these hybrids was performed as a combination of surface initiated atom transfer polymerisation and click reactions. Thermal behaviour and the colloidal stability of these hybrid particles were studied. The role of the PEO block in the colloidal stability of the particles was crucial. Finally, multiresponsive hybrid block copolymers based on N-vinylcaprolactam and 2-dimethylaminoethyl methacrylate was prepared. The thermal properties of these block copolymers can be tuned by varying the chain length of PVCL block. On the other hand the thermal behaviour of PDMAEMA block is highly dependent on the environmental conditions like pH and ionic strength. Tässä tutkimuksessa valmistettiin useita erilaisia epäorgaanisista substraateista ja orgaanisista polymeereista koostuvia hybridimateriaaleja. Lisäksi valmistettiin lämpötila- ja pH-responsiivisia lohkokopolymeereja. Työssä käytetyt epäorgaaniset substraatit olivat montmorilloniittisavi, silikakapillaarit sekä huokoiset silikapartikkelit. Substraatin pintaan oksastettiin kovalenttisesti polymeeriketjuja kontrolloiduilla radikaalipolymerointitekniikoilla. Montmorilloniittisaven pintaan kiinnitettiin butyyliakrylaatin ja metyylimetakrylaatin kopolymeereja kontrolloidulla radikaalipolymeroinnilla.…