Oxygen tolerant copper-mediated reversible deactivation radical polymerization

The focus of this Ph.D. thesis is to develop Cu-RDRP and render it a more user-friendly and versatile platform. For this purpose, three different Cu-RDRP methodologies, Cu(0)-wire mediated RDRP (Chapter 2), photoinduced Cu-RDRP (Chapter 3) and aqueous Cu-RDRP with the pre-disproportionation of Cu(I) (Chapter 4), are studied in the absence of conventional deoxygenation. Without the use of extrinsic oxygen scavengers and reducing agents, a range of well-defined polymers (i.e. poly(acrylates), poly(methacrylates), poly(styrene) and poly(acrylamides)) are synthesized under various conditions (temperatures, solvents, reaction scale). In all the different oxygen tolerant approaches, high end-group fidelity is maintained, leading to well-defined block copolymers in-situ. In each of the three different approaches, the concentration of oxygen in the polymerization reactions is monitored in-situ with the use of an oxygen probe, and the mechanism of oxygen consumption is investigated and discussed. Furthermore, the role of the polymerization reagents on the evolution of oxygen consumption is elucidated, highlighting the importance of each component. Apart from the oxygen tolerant nature of these platforms, the effect of UV-irradiation on Cu-based complexes is investigated (Chapter 5), providing insights into the excited state dynamics and the photo-redox behaviour of Cu(II)-based complexes, and the effect of different aliphatic amines on photoinduced Cu-RDRP

Rapidly self-deoxygenating controlled radical polymerization in water via in situ disproportionation of Cu(i)

Rapidly self-deoxygenating Cu-RDRP in aqueous media is investigated. The disproportionation of Cu(I)/Me6Tren in water towards Cu(II) and highly reactive Cu(0) leads to O2-free reaction environments within the first seconds of the reaction, even when the reaction takes place in the open-air. By leveraging this significantly fast O2-reducing activity of the disproportionation reaction, a range of well-defined water-soluble polymers with narrow dispersity are attained in a few minutes or less. This methodology provides the ability to prepare block copolymers via sequential monomer addition with little evidence for chain termination over the lifetime of the polymerization and allows for the synthesis of star-shaped polymers with the use of multi-functional initiators. The mechanism of self-deoxygenation is elucidated with the use of various characterization tools, and the species that participate in the rapid oxygen consumption is identified and discussed in detail

Aqueous copper-mediated reversible deactivation radical polymerization (RDRP) utilizing polyetheramine derived initiators

Copper-mediated reversible deactivation radical polymeriation (Cu-RDRP) in aqueous media has been employed to synthesize temperature-responsive block copolymers, utilizing both hydrophobic and hydrophilic amide functional macroinitiators derived from polyetheramines (Jeffamines™). The in situ and rapid diproportionation of Cu(I)Br/Me6TREN in water is exploited for the efficient homopolymerization of N-isopropyl acrylamide (NIPAM) and dimethyl acrylamide (DMA), at near full conversions (>99%), with low dispersity (Đ < 1.18) and with a range of molar masses. The Jeffamine™-derived macroinitiators were used for both the synthesis of homopolymer and for one-pot chain extensions and block copolymerizations (i.e. Jeffamine™-PNIPAM-b-PDMA). The obtained polymers exhibit controlled thermoresponsive aggregation behaviour which varies depending on the hydrophilicity/hydrophobicity of the macroinitiators and the composition of the block copolymers. Thermal analysis and dynamic light scattering (DLS) give an insight into the effect of these macroinitiators on the thermoresponsive aggregation behaviour of the synthesized polymers

Localised polymerisation of acrylamide using single-barrel scanning electrochemical cell microscopy

Single-barrel scanning electrochemical cell microscopy has been adapted for polymerisation of acrylamide in droplet cells formed at gold electrode surfaces. Localised electrochemical atom transfer radical polymerisation enables controlled synthesis and deposition of polyacrylamide or synthesis of polyacrylamide brushes from initiator-functionalised electrode surfaces

Copper mediated reversible deactivation radical polymerization in aqueous media

Key advances within the past 10 years have transformed copper mediated radical polymerization from a technique which was not very tolerant to protic media into a range of closely related processes capable of control over the polymerization of a wide range of monomers in pure water at ppm catalyst loadings; yielding water soluble macromolecules of desired molecular weight, architecture and chemical functionality, with applications ranging from drug delivery to oil field recovery. In this review we highlight and critically evaluate the synthetic methods that have been developed to control radical polymerization in water using copper complexes, identify future areas of interest and challenges still to be overcome

Polymerisable surfactants for polymethacrylates using catalytic chain transfer polymerisation (CCTP) combined with sulfur free-RAFT in emulsion polymerisation

Statistical copolymers of methacrylic acid and methyl methacrylate were synthesised via free radical catalytic chain transfer polymerisation (CCTP) in emulsion to form a hydrophilic emulsifier/surfactant. The vinyl-terminated oligomers were in turn utilised as chain transfer agents, with no further purification, for the formation of diblock copolymers with butyl and methyl methacrylate which constitutes the emulsifier via sulfur-free reversible addition–fragmentation chain transfer polymerisation (SF-RAFT). In turn these polymers were solubilized with various concentrations of ammonium hydroxide and utilised in the surfactant-free emulsion polymerization of butyl methacrylate using persulfate initiators, which also stabilized the polymer particles with observed no coagulation, with solid contents as high as 40%

Ultra-low volume oxygen tolerant photoinduced Cu-RDRP

We introduce the first oxygen tolerant ultra-low volume (as low as 5 μL total reaction volume) photoinduced copper-RDRP of a wide range of hydrophobic, hydrophilic and semi-fluorinated monomers including lauryl and hexyl acrylate, poly(ethylene glycol methyl ether acrylate) and trifluoroethyl (meth)acrylate. In the absence of any external deoxygenation, well-defined homopolymers can be obtained with low dispersity values, high end-group fidelity and near-quantitative conversions. Block copolymers can be efficiently synthesized in a facile manner and the compatibility of the system to larger scale polymerizations (up to 0.5 L) is also demonstrated by judiciously optimizing the reaction conditions. Importantly, the online monitoring of oxygen consumption was also conducted through an oxygen probe and the role of each component is identified and discussed

Exploiting catalytic chain transfer polymerization for the synthesis of carboxylated latexes via sulfur‐free RAFT

We present a systematic study of incorporating carboxyl groups into latex particles to enhance colloidal stability and the physical properties of the latex. Statistical copolymers of methacrylic acid and methyl methacrylate) were synthesized via catalytic chain transfer polymerization (CCTP) in emulsion. The vinyl‐terminated oligomers were in turn successfully utilized as chain transfer agents for the formation of diblock and pseudo triblock copolymers via sulfur‐free reversible addition–fragmentation chain transfer polymerization (SF‐RAFT). These copolymers were characterized using 1H NMR, size exclusion chromatography (SEC), dynamic light scattering (DLS), dynamic mechanical analysis (DMA), contact angle measurements and matrix‐assisted laser desorption/ionization time of flight mass spectroscopy (MALDI‐TOF‐MS) techniques. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 201

Automatic peak assignment and visualisation of copolymer mass spectrometry data using the “genetic algorithm”

Copolymer analysis is vitally important as the materials have a wide variety of applications due to their tunable properties. Mass spectrometry data for copolymer samples can be very complex due to the increase in the number of species when the polymer chains are formed by 2 or more monomeric units. In this paper, we describe the use of the genetic algorithm for automated peak assignment of copolymers synthesised by a variety of polymerization methods. We find that in using this method we are able to easily assign copolymer spectra in a few minutes and visualise them into heatmaps. These heatmaps allowed us to look qualitatively at the distribution of the chains, showing how they alter with different polymerization techniques, and by changing the initial copolymer composition. This methodology is shown to be simple to use and requires little user input, which makes it well suited for use by less expert users. The data outputted by the automatic assignment may also allow for more complex data processing going forward

Microphase separation of highly amphiphilic, low N polymers by photoinduced copper-mediated polymerization, achieving sub-2 nm domains at half-pitch

The lower limit of domain size resolution using microphase separation of short poly(acrylic acid) homopolymers equipped with a short fluorinated tail, posing as an antagonist 'A block' in pseudo AB block copolymers has been investigated. An alkyl halide initiator with a fluorocarbon chain was utilized as a first 'A block' in the synthesis of low molecular weight polymers (1400-4300 g mol -1) using photoinduced Cu(ii)-mediated polymerization allowing for very narrow dispersity. Poly(tert-butyl acrylate) was synthesized and subsequently deprotected to give very low degrees of polymerization (N), amphiphilic polymers with low dispersity (D = 1.06-1.13). By exploiting the high driving force for demixing and the well-defined 'block' sizes, we are able to control the nanostructure in terms of domain size (down to 3.4 nm full-pitch) and morphology. This work demonstrates the simple and highly controlled synthesis of polymers to push the boundaries of the smallest achievable domain sizes obtained from polymer self-assembly