Exploring crosslinked networks of polymers and hybrid cellulose materials

Abstract: The field of polymer chemistry has in recent decades had an immense development, resulting in new functional materials with groundbreaking applications. This has been driven partly by strong interdisciplinary alliances between the fields of medicine, biology, chemistry, and materials science. Thermoresponsive block copolymers, have been built for their ability to self-assemble, giving possibility of encapsulation and release of medicine. The dendritic polymer family have been demonstrated as a prime example of highly reactive and interactive functional materials, suitable for biomedical applications. The importance of amines is greatly appreciated in general and especially in polymer chemistry, due to their nucleophilic characteristics in reactions, but also for their ability to interact with other species. There’s also an increase in awareness of standard of living, the effects of climate change and population growth. These are challenges, in need of our outmost focus and knowledge, to direct our path to, towards a more bio based circular economy. This starts, in Sweden, by taking better care of our forest and utilizing its resourceful crop. This thesis seek out spontaneous crosslinking, of various functional polymers, with focus towards hybridizing with nanocellulosic material.Initially, interactive permanently charged amine-functional thermoresponsive tri- and star-block copolymers were composed. These were evaluated and used as electrostatic macro-crosslinker of cellulose nanofibrils (CNFs), resulting in thermoresponsive, low dry weight content hydrogels, with notable temperature dependent storage modulus.Secondly, reactive and interactive amine-functional dendritic-linear-dendritic (DLD) species were constructed and evaluated in vitro and in vivo. The DLD scaffolds were utilized as fast-degrading, inhibiting surgical site infection (SSIs) antibacterial hydrogel coatings. The crosslinking of the poly(ethylene glycol) (PEG) system was optimized in order to create a two component system, which could be applied with dual syringes. This enabled instantaneous gelation under physiological conditions. The hydrogels moduli could be varied to match various tissues.Thirdly, insights and characterizations were provided in the commercial heterofunctional poly(amido amine) carboxylate hyperbranched Helux. Amine post-modifications and intrinsic heterofunctionality alterations of Helux were explored, by increasing the molecular weight and forming Helux self-crosslinked films. Furthermore, two component hydrogels based on Helux and PEG demonstrated curing temperature dependent moduli in the rheometer.Finally, utilizing Helux in combination with CNFs to demonstrate the potential to mix on the nanoscale without aggregation. The CNF-Helux could form hydrogels, and wet-stable thermo-crosslinked CNF-Helux composites assemblies such as films and aerogels, with further excess of amines ready for post-modifications of the crosslinked 3D-network.