Details

Autor(en) / Beteiligte

• van Dam-Engelbert, Annemieke Irene

Titel

Improving the world one monomer at a time: In silico and on silica investigations of polymerization reactions and polymers

Ort / Verlag

ProQuest Dissertations & Theses

Erscheinungsjahr

2024

Link zum Volltext

• ProQuest

Quelle

ProQuest Dissertations & Theses A&I

Beschreibungen/Notizen

• Surface modification is often used to enhance or adapt surface properties. In printing industries, heavily fluorinated materials are often applied as antifouling coating to prevent polymeric fouling of printhead nozzles. Such heavily fluorinated materials are toxic and will soon be prohibited in the European Union. A less toxic alternative is thus desired. Moreover, the durability of such a coating could be improved by rendering these coatings self-healing. In chapter 1 of this thesis, the current status of the field is explored. A general overview of grafting techniques for coatings is provided, and various polymerization techniques are discussed with a focus on polymer brushes. More specifically, antifouling and self-healing coatings are discussed. On the topic of bulk polymers, we touch upon dynamic covalent chemistry, SuFEx polymerization, and natural polymers such as lignin. A brief summary of the history of DFT and its current use, is provided as well. In chapter 2 of this thesis, the self-healing and antifouling properties of a range of partially fluorinated polymer brushes are reported. Eleven methacrylates are selected with linear side chains with varying degree of fluorination. After synthesis of six of the methacrylates, polymer brushes of all monomers are made by surface-initiated atom transfer radical polymerization (SI-ATRP). Characterization of the coatings is done with static contact angle measurements, ellipsometry, AFM and XPS, and the antifouling property of each coating is evaluated with confocal fluorescence microscopy. As expected, the polymer brushes with fully fluorinated side chains, be it short, medium or long, show excellent antifouling ability. With a decrease in the degree of fluorination, the antifouling capability decreases as well. Remarkably, the non-fluorinated side chains perform significantly better than their singly fluorinated counterparts. A correlation between the antifouling ability and the minimal surface tension of the polymer brushes is established. Furthermore, the self-healing ability is determined by repeated exposure to pH 3 solutions and a 120 °C atmosphere. Under these conditions, all coatings are found to be fully self-healing. Additionally, no damage is observed in the self-healing experiments of the longest non-fluorinated brushes. To investigate the remarkable performance of the longest non-fluorinated side chain, we test a range of fluorine-free polymer brushes in the work described in chapter 3. Synthesis, polymerization, characterization and self-healing performance testing is similar to the work described in chapter 2. Polymer brushes with linear side chains of seven or less carbons display reversible damage, while polymer brushes with linear side chains of nine or more carbons are unharmed by repeated pH 3 exposure. We propose that longer side chains can pack tightly, preventing H3O + reaching the ester bonds in the backbone of the polymer chain. Shorter chains cannot pack tightly enough, therefore acidic hydrolysis of the backbone will occur. To further support this hypothesis, we observe that coatings derived from polymers with branched side chains show reversible damage. Overall, the work in this chapter provides a promising basis for how fluorine-free coatings could still be made antifouling and/or self-healing.