Make a break with polyphosphoesters: From sequence control to biodegradable polymers and biomedical materials

This thesis offers an in-depth exploration of the field of polyphosphoesters (PPEs) and their potential applications. The degradability of polymeric materials is a crucial property for many applications in today's society, with an increasing demand for (bio)degradable alternatives in packaging materials and beyond. PPEs draw inspiration from natural structures like RNA and DNA and have been proposed as degradable polymers for medical applications, providing a wide range of functionalities. In this thesis, the fundamental profiles of polymerization and degradation kinetics were investigated to apply this knowledge in the development of customized polymer materials.

Chapter 2 focuses on a systematic study of the degradation kinetics of different water-soluble PPEs. The research highlights the adjustability of degradation speed in PPEs, resulting in polymers with half-life times ranging from hours to years. Building upon the understanding of PPE degradation, Chapters 3 to 7 delved into the development of various copolymers involving PPEs. In Chapter 3, the degradation properties of polylactic acid (PLA) are tailored to make it seawater degradable by incorporating RNA-inspired breaking points along the polymer chain. Chapter 4 presents the first copolymerization of phosphoester (PE) with trimethylene carbonates (TMC), enabling the fine-tuning of properties and investigating polymerization kinetics and randomization through transesterification using real-time NMR spectroscopy. Chapter 5 explores the mechanical, biological, and degradation properties of high molar mass random P(TMC-co-PE) copolymers, demonstrating their potential as rubber-like antifouling materials for medical applications with controlled hydrolytic degradation. Chapter 6 introduces the first MRI-traceable polymers by modifying the chemistry of PPEs, which can be used for imaging and drug delivery applications. In vivo MRI images, free from background interference, are captured, furthermore the in vivo degradation of the PPEs was demonstrated. Chapter 7 expands the range of PPE copolymers by synthesizing binary and ternary copolymers from different PPE subclasses, enabling the creation of various gradient copolymers with adjustable amphiphilicity and MRI-traceable properties. Chapter 8 provides a vision for the future development of PPEs, highlighting the most promising trends and potential applications in various fields.

Overall, this thesis provides a comprehensive exploration of PPEs, and paves the way for further advancements in the field.