Synthesis of functional polymers via oxyanion and iodide catalyzed living radical polymerizations in emulsion, solution and bulk systems and their applications

• Main Author: Mao, Weijia
• Other Authors: Atsushi Goto
• Format: Thesis-Doctor of Philosophy
• Language: English
• Published: Nanyang Technological University 2022
• Subjects: Science::Chemistry::Organic chemistry::Polymers
• Online Access: https://hdl.handle.net/10356/155353
• Institution: Nanyang Technological University

Chapter 1 introduced the general concept of living radical polymerization (LRP), three most widely-used LRP methods were introduced, and their advantages and disadvantages were discussed. The mechanism of reversible complexation mediated polymerization (RCMP) was introduced, and its advantages over other LRPs have been discussed. The current catalysts and current limitations of RCMP were also introduced. The motivations and aims for the works in this Thesis were explained. In Chapter 2, oxyanions (carboxylate, nitrate, phosphate, and sulfonate) were systematically studied as new RCMP catalysts. The oxyanion-catalyzed RCMP yielded polymers with relatively high conversion in short reaction times, maintaining low dispersity. The high chain-end iodide livingness of the obtained polymers also enabled the synthesis of block copolymers. Oxyanion compounds are inexpensive, little toxic, and amenable to broad molecular structures. These features are attractive for RCMP catalysis. The development of oxyanions as RCMP catalysts also contributed to development of air-tolerant RCMP in Chapter 3. In Chapter 3, air-tolerant RCMP was developed. The air-tolerant RCMP system employed an aldehyde, N-hydroxyphthalimide (NHPI), and an amine for both oxygen consumption and catalysis. The aldehyde (RCHO) consumed oxygen and was converted to a carboxylic acid (RCOOH) catalyzed by NHPI. The carboxylic acid was subsequently converted to a carboxylate anion (RCOO−) in the presence of the amine. The generated RCOO− worked as an RCMP catalyst. This system does not require deoxygenation before polymerization and is amenable to methacrylates and styrene. The development of air-tolerant RCMP enhances the practicality of RCMP. In Chapter 4, RCMP was explored in the emulsion system. We systematically studied the effect of emulsifiers, catalysts, and alkyl iodide initiating dormant species in emulsion RCMP for homopolymerization. The kinetic and mechanistic aspects of emulsion RCMP were also elucidated by partitioning tests of the initiating dormant species and particle number analysis in the course of polymerization. Emulsion RCMP can afford stable polymer latex with relatively high solid contents (up to nearly 50%). The emulsion RCMP combines the advantages of emulsion polymerization such as efficient heat transfer, low viscosity, and high polymerization rate with those of RCMP, such as no use of special capping agents or toxic catalysts. The high solid content, high chain-end fidelity, good monomer versatility achievable in the emulsion RCMP would also be attractive for polymer material design and industrial applications. In Chapter 5, we further explored emulsion RCMP for copolymerization. We carried out block copolymerization exploiting the high iodide chain-end fidelity of poly(methacrylate) −I (PMMA−I) obtained in Chapter 4, successfully yielding block copolymers with high monomer conversions in relatively short reaction times. Random copolymerizations were also carried out in emulsion RCMP, various gradient copolymers were obtained, and monomer sequence can be tuned by the reaction temperature. We also studied using solution RCMP for the synthesis of hydrophilic-amphiphilic block copolymers using monomers with anti-fouling properties and applied the obtained block copolymers for anti-fouling coating on membranes. The accessibility of RCMP in aqueous media to a wide range of monomers was successfully demonstrated.