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.

Polymerkemin har under de senaste decennierna haft en enorm utveckling, vilket har resulterat i nya funktionella material med banbrytande applikationer. Denna utveckling har drivits på av starka tvärvetenskapliga allianser mellan medicin, biologi, kemi och materialvetenskap. Termoresponsiva block-sampolymerer har bland annat tagits fram för sin förmåga att själv-organiseras, vilken möjliggör inkapsling och frisättning av medicin. Den dendritiska polymerfamiljen har visat sig vara ett utmärkt exempel på högreaktiva och interaktiva funktionella material, speciellt lämpliga för biomedicinska tillämpningar. Betydelsen av aminer är stor i allmänhet och speciellt inom polymerkemin, tack vare deras nukleofila egenskaper i reaktioner, men också för deras förmåga att interagera med andra fysikaliska konstellationer. Det finns också en ökad medvetenhet om vår ökande levnadsstandard, effekterna av klimatförändringar och jordens befolkningstillväxt. Dessa utmaningar, behöver vårt yttersta fokus och ökad kunskap, för att styra våra steg mot en mer biobaserad cirkulär ekonomi. I Sverige skulle vi kunna ta bättre hand om vår skog och utnyttja dess fina råmaterial och förädla den till nya material. Denna avhandling strävar efter spontan tvärbindning av olika funktionella polymerer, med fokus på hybridisering med nanocellulosa-material.

Initialt framställdes interaktiva, permanent laddade, amin-funktionella termoresponsiva tri- och stjärnblocksampolymerer. Dessa utvärderades och användes som elektrostatisk makro-tvärbindare för cellulosa nanofibriller (CNF), vilket resulterade i hydrogeler med låg torrhalt och anmärkningsvärd termoresponsivitet och skjuvningsmodul.

För det andra utvecklades och utvärderades reaktiva och interaktiva aminfunktionella dendritiska linjär-dendritiska (DLD)-polymerer in vitro och in vivo. DLD-polymererna användes som antibakteriella hydrogeler som var snabbnedbrytande och verkade hämmande för kirurgiskt påverkad sårinfekiton (SSI). Tvärbindning av poly(etylen glykol) (PEG) systemet optimerades för snabb applicering under fysiologiska förhållanden i from av tvåkomponentssystem samt för att kunna matcha olika vävnaders skjuvningsmodul.

För det tredje introducerades och karakteriserades Helux, den hyperförgrenade kommersiella heterofunktionella poly(amidoamin) karboxylat polymeren. Aminreaktioner utfördes för att demonstrera lättillgängliga modifieringar av Helux. Hetero-funktionaliteten utvärderades genom att öka molekylvikten och sedan bilda självtvärbundna Heluxfilmer. Dessutom framställdes även tvåkomponents-hydrogeler baserat på Helux och PEG som visade temperaturhärdningsberoende skjuvningsmodul.

Slutligen användes Helux i kombination med CNF för att visa potentialen i att blanda på nanonivå utan aggregering. CNF-Helux visade sig kunna bilda hydrogeler och våtstabila termo-tvärbundna CNF-Helux-kompositsammansättningar, såsom filmer och aerogeler, redo för ytmodifiering av kvarvarande amin-grupper i de bildade 3D-nätverken.

The environmental effects caused by the use of fossil-based resources have intensified and driven society and research towards new materials and processes that utilise renewable resources. Within the development of new materials, wood has been identified as a raw-material from which high performing materials can be derived. One such material is cellulose nanofibrils (CNFs) which are capable of replacing several currently used fossil-based materials. However, for CNFs to exhibit the required material properties they need to be chemically or physically modified. This means that the properties of the CNFs can be specifically adapted to fit the demand in particular areas, for example electrical energy storage. In these applications it is the mechanical properties; the large, easily functionalised surface and ability to be moulded into 3D shapes that make CNFs a highly interesting raw material.

This thesis explores the formation and functionalisation of CNF- and fibre-based materials and their novel use in applications such as energy storage. The wet stability of the materials was achieved by crosslinking and ice templating the fibrils by a novel freezing procedure, which makes it possible to avoid the use of freeze-drying and subsequent crosslinking. Using colloidal probe atomic force microscopy adhesion measurements, hemiacetals were shown to be formed between the aldehyde-containing fibrils when they are brought into molecular contact, for example during ice templating. Hemiacetal crosslinked aerogels have been shaped and functionalised to demonstrate their application as biomimetic structural composites, electrical circuits and electrical cells. In addition, crosslinked, light-weight 3D fibre networks were prepared with á similar chemistry by a self-assembly process of pulp fibres. These networks could be dried under ambient conditions and the materials formed were wet-stable due to the hemiacetal crosslinks formed in the fibre–fibre contacts, which provided the networks with excellent mechanical properties and shape recovery capacity in water.

Finally, using a newly developed polyampholyte and mixing it with CNFs, heterofunctional composite films and aerogels could be prepared. By activating crosslinkable groups in these composite materials, they were able to undergo further water based chemical functionalisation. In this highly dispersed state, the composite could be irreversibly crosslinked by a hydrothermal treatment to create transparent, low solid content hydrogels.