abstract: Amphipathic molecules consist of hydrophilic and hydrophobic regions, which make them surface-active molecules. The uniqueness of these compounds results in inducing low surface tension and self-assembly of the molecules inside a solvent which have been exploited in personal care, the oil industry and agriculture industry. Amphipathic molecules are also used in the healthcare industry as drug delivery systems and other bio-nanotechnology applications. In this thesis, a novel series of grafted siloxanes have been explored for their probable application in the healthcare industry. The siloxanes are grafted with poly(ethylene glycol) (PEG) and quaternary ammonium salt (QUAT). The effects of varying 1) molar ratios of QUAT to PEG and 2) PEG chain length on contact angle, surface tension, critical micelle concentration (CMC), and micelle assembly properties were studied. In contact angle experiments, the hydrophilicity of grafted siloxanes increased by grafting PEG and QUAT. The amphiphilicity increases and CMC decreases as the PEG chain length shortens. Adding QUAT also reduces CMC. These trends were observed in surface tension and Isothermal Titration Calorimetry experiments. A change in self-assembly behaviour was also observed in Dynamic Light Scattering experiments upon increasing the PEG chain length and its ratio relative to the quaternary ammonium in the siloxane polymer. These polymers have also been studied for their probable application as a sensitive 1H NMR spectroscopy indicator of tissue oxygenation (pO2) based on spectroscopic spin-lattice relaxometry. The proton imaging of siloxanes to map tissue oxygenation levels (PISTOL) technique is used to map T1 of siloxane polymer, which is correlated to dynamic changes in tissue pO2 at various locations by a linear relationship between pO2 and 1/T1. The T1-weighted echo spin signals were observed in an initial study of siloxanes using the PISTOL technique. The change in the ratio of QUAT to PEG and the varying chain length of PEG have a significant effect on the physical property characteristics of siloxane graft copolymers. The conclusions and observations of the present work serve as a benchmark study for further development of adaptive polymers and for the creation of integrated “nanoscale” probes for PISTOL oximetry and drug delivery. / Dissertation/Thesis / Masters Thesis Chemical Engineering 2018

<p>The interactions between polymers and components of biological systems are an important area of interest within the fields of tissue engineering, polymer chemistry, medicine and biomaterials. In order to create such a biomimetic material, it must show the inherent ability to reproduce or elicit a biological function. How do we design synthetic materials in order to direct their interactions with biological systems?</p><p>This thesis contributes to this research with aspects of how polymers interact with biological materials with the help of ionic interactions. Polyesters, biodegradable or not, may after a hydrolytic cleavage interact ionically with protonated amines by the liberated carboxylate functions. Amines are found in proteins and this fact will help us to anchor proteins to polyester surfaces. Another type of interaction is to culture cells in polymeric materials, i.e. scaffolds. We have been working on compliant substrates, knitted structures, to allow cell culture in three dimensions. A problem that arises here is how to get a high cell seeding efficiency? By working on the interactions between polymers, proteins and finally cells, it is possible to create a polarized protein membrane that allows for very efficient cell seeding, and subsequent three dimensional cell cultures. Finally a synthetic route to taylor interaction was developed. Here a group of polymers known as ionomers were synthesized. In our case ionic end groups have been placed onto biodegradable polycarbonates, we have created amphiphilic telechelic ionomers. Functionalization, anionic or cationic, changes the properties of the material in many ways due to aggregation and surface enrichment of ionic groups. It is possible to add functional groups for a variety of different interactions, for example introducing ionic groups that interact and bind to the complementary charge of proteins or on the other hand one can chose groups to prevent protein interactions, like the phosphorylcholine zwitterionomers. Such interactions can be utilized to modulate the release of proteins from these materials when used in protein delivery applications. The swelling properties, Tg, degradation rate and mechanical properties are among other things that will easily be altered with the choice of functional groups or backbone polymer.</p>

The interactions between polymers and components of biological systems are an important area of interest within the fields of tissue engineering, polymer chemistry, medicine and biomaterials. In order to create such a biomimetic material, it must show the inherent ability to reproduce or elicit a biological function. How do we design synthetic materials in order to direct their interactions with biological systems? This thesis contributes to this research with aspects of how polymers interact with biological materials with the help of ionic interactions. Polyesters, biodegradable or not, may after a hydrolytic cleavage interact ionically with protonated amines by the liberated carboxylate functions. Amines are found in proteins and this fact will help us to anchor proteins to polyester surfaces. Another type of interaction is to culture cells in polymeric materials, i.e. scaffolds. We have been working on compliant substrates, knitted structures, to allow cell culture in three dimensions. A problem that arises here is how to get a high cell seeding efficiency? By working on the interactions between polymers, proteins and finally cells, it is possible to create a polarized protein membrane that allows for very efficient cell seeding, and subsequent three dimensional cell cultures. Finally a synthetic route to taylor interaction was developed. Here a group of polymers known as ionomers were synthesized. In our case ionic end groups have been placed onto biodegradable polycarbonates, we have created amphiphilic telechelic ionomers. Functionalization, anionic or cationic, changes the properties of the material in many ways due to aggregation and surface enrichment of ionic groups. It is possible to add functional groups for a variety of different interactions, for example introducing ionic groups that interact and bind to the complementary charge of proteins or on the other hand one can chose groups to prevent protein interactions, like the phosphorylcholine zwitterionomers. Such interactions can be utilized to modulate the release of proteins from these materials when used in protein delivery applications. The swelling properties, Tg, degradation rate and mechanical properties are among other things that will easily be altered with the choice of functional groups or backbone polymer.