Bioinspired amphipilic polymer conetworks

Student thesis: Doctoral Thesis

Abstract

Nature has developed materials with high toughness and strength, which is usually not possible in man-made materials. More recently bioinspiration has aided development of highly mechanically reinforced polymeric materials. Key properties of amphiphilic polymer conetworks (APCNs) include transparency and swellability in water and hydrocarbons. Unfortunately, the mechanical properties are not high enough to be used in a wide range of applications where the key properties of these materials could otherwise be beneficial. In this thesis, several strategies to improve the mechanical properties of APCNs and extend their potential range of applications using different processing techniques are explored. Inspired by spider silk, we used triblock copolymers with peptidic repeating units, poly-β-benzyl-l-aspartate (PBLA), that form β-sheets and/or α-helices to tailor the properties of APCNs. The effect of varying the number of peptide repeating units and concentration of hydrophobic to hydrophilic domains were studied. Through this study, the created hydrogen bondings showed the possibility to tailor the properties of the material to different applications. As many natural structures use hierarchical reinforcement to provide greater resilience, a second level of reinforcement using cellulose nanocrystals (CNCs) was also studied. A type of CNCs modified with hydrophobic moieties was explored to be used in the initial hydrophobic monomer mixture. The amount of solvent used during processing was studied as well as the reinforcement with up to 22 wt% CNCs. This work showed the possibility of a two-level hierarchical reinforcement of APCNs which gives the possibility to have high mechanical properties in the dry and swollen state. Finally, APCNs were used as a base material for the shell of double emulsion microcapsules prepared using LEGO® inspired glass capillary devices. Inspired by pollen grains, the hydration and dehydration of the capsules was studied to understand the suitability of these microcapsules for use in different media. The capsules were also loaded with platinum nanoparticles to study their catalytic effect when mixed with hydrogen peroxide. The surface functionalization of the capsules was studied by adding different moieties such as Cy5-PEG5000-cholesterol. This thesis systematically investigated the properties of APCNs, explored different enhancement strategies and developed a new type of APCNs, greatly enhancing the potential to tailor APCNs for a wider range of applications.
Date of Award5 May 2023
Original languageEnglish
Awarding Institution
  • University Of Strathclyde
SponsorsUniversity of Strathclyde
SupervisorNico Bruns (Supervisor) & K. H. Aaron Lau (Supervisor)

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