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%

Dihydrolevoglucosenone (Cyrene™) as a bio-renewable solvent for Cu(0)wire-mediated reversible deactivation radical polymerization (RDRP) without external deoxygenation

Biorenewable dihydrolevoglucosenone (Cyrene™) is used as an effective dipolar aprotic solvent for Cu(0) wire-mediated RDRP of various monomers without external deoxygenation being applied

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

Aggregation-induced emission poly(meth)acrylates for photopatterning via wavelength-dependent visible-light-regulated controlled radical polymerization in batch and flow conditions

A robust wavelength-dependent visible-light-regulated reversible-deactivation radical polymerization protocol is first reported for the batch preparation of >20 aggregation-induced emission (AIE)-active polyacrylates and polymethacrylates. The resulting polymers possess narrow molar mass distributions (Đ ≈ 1.09–1.25) and high end-group fidelity at high monomer conversions (mostly >95%). This demonstrated control provides facile access to the in situ generation of complex sequence-defined tetrablock copolymers in one reactor, even while chain extending from less reactive monomers. Polymerizations can be successfully carried out under various irradiation conditions, including using UV, blue, green, and red LED light with more disperse polymers obtained at the longer, less energetic, wavelengths. We observe a red shift and wavelength dependence for the most efficient polymerization using LED illumination in a polymerization reaction. We find that the absorption of the copper(II) complex is not a reliable guide to reaction conditions. Moreover, the reported protocol is readily translated to a flow setup. The prepared AIE-active polymers are demonstrated to exhibit good photopatterning, making them promising materials for applications in advanced optoelectronic devices

UV irradiation of Cu-based complexes with aliphatic amine ligands as used in living radical polymerization

The effect UV irradiation on Cu(II)-based complexes with aliphatic amine ligands is investigated. Four aliphatic amines are used as ligands and Cu(II)Br2 as the metal source for the formation of catalyst complexes that can be used for the photoinduced Cu-RDRP of methyl acrylate. Different characterization techniques such as transient electronic absorption spectroscopy (TEAS), ultraviolet-visible (UV-Vis) spectroscopy, electrospray ionization time of flight mass spectrometry (ESI-ToF-MS) and cyclic voltammetry (CV) are applied in order to provide insights into the catalyst behaviour upon photo-irradiation. The excited-state dynamics, the electrochemical behaviour of the Cu(II)/Cu(I) redox couples and the detection of different species upon complexation of the ligand to the metal center (before and after UV irradiation) are further depicted in the quality of the obtained polymers

Efficient N-Type Organic Electrochemical Transistors and Field-Effect Transistors Based on PNDI-Copolymers Bearing Fluorinated Selenophene-Vinylene-Selenophenes

n-Type organic electrochemical transistors (OECTs) and organic field-effect transistors (OFETs) are less developed than their p-type counterparts. Herein, polynaphthalenediimide (PNDI)-based copolymers bearing novel fluorinated selenophene-vinylene-selenophene (FSVS) units as efficient materials for both n-type OECTs and n-type OFETs are reported. The PNDI polymers with oligo(ethylene glycol) (EG7) side chains P(NDIEG7-FSVS), affords a high µC* of > 0.2 F cm−1 V−1 s−1, outperforming the benchmark n-type Pg4NDI-T2 and Pg4NDI-gT2 by two orders of magnitude. The deep-lying LUMO of −4.63 eV endows P(NDIEG7-FSVS) with an ultra-low threshold voltage of 0.16 V. Moreover, the conjugated polymer with octyldodecyl (OD) side chains P(NDIOD-FSVS) exhibits a surprisingly low energetic disorder with an Urbach energy of 36 meV and an ultra-low activation energy of 39 meV, resulting in high electron mobility of up to 0.32 cm2 V−1 s−1 in n-type OFETs. These results demonstrate the great potential for simultaneously achieving a lower LUMO and a tighter intermolecular packing for the next-generation efficient n-type organic electronics

Improving the accessibility of transition metal mediated radical polymerization

This PhD thesis aims to bring new perspectives on the field of Transition Metal Catalyzed Polymerization methods, by investigating alternative synthetic approaches for the generation of various polymers, many of which having high prospect for industrially related use. For this purpose, two distinctive transition metal catalyzed polymerization methods, namely Catalytic Chain Transfer Polymerization (CCTP) and Copper-mediated Reversible Deactivation Radical Polymerization (Cu-RDRP) were examined under various conditions, and used for the generation of polymers which either have compelling applications or are well-defined. For simplicity, this thesis can be divided into two parts; the first part focuses on the use of CCTP in combination with surfactant-free emulsion polymerizations (Chapter 2 and Chapter 3). The second part which focuses on Cu-RDRP, aims to examine the limits of this controlled radical polymerization method under the simultaneous introduction of oxygen tolerance and either continuous flow chemistry or the use of a bio-renewable solvent (Chapter 4 and Chapter 5). Initially, the ability of CCTP-derived methacrylic macromonomers to act as stabilizers in surfactant-free emulsion polymerizations was investigated (Chapter 2). Although these macromonomers are highly versatile, studies on their behaviour as stabilizers in emulsion processes had been limited. In Chapter 2, ionic and non-ionic CCTP-synthesized oligomers were compared with a conventionally used surfactant (SDS) for their stabilizing effect on surfactant-free emulsion polymerization of hydrophobic monomers. The effect of the stabilizers (ionic vs non-ionic vs low molar mass surfactants) on the properties of the final product was examined and with the alliance of different characterization methods, a statistical method explaining the particle size variations due to the hydrophobic monomer selection was created. In Chapter 3, the potential use of this type of macromonomers in industrial applications (e.g. in agrochemical industry) was examined. Specifically, amphiphilic macromonomers obtained through CCTP with varying acid content, were used for the development of stable aqueous dispersions of an active ingredient (AI), namely cyantraniliprole (CYNT). Upon finding the optimum conditions for sufficient CYNT dispersion, the direct application of polymeric coating around the CYNT particles was investigated. For this purpose, surfactant-free emulsion polymerization of a monomer mixture under starved-feed conditions was carried out in the presence of the CYNT dispersion. Finally, the release profile of cyantraniliprole in aqueous media was investigated. The second part of this dissertation was focused on a different type of Transition Metal Catalyzed Polymerization, namely Cu-RDRP. In this part of the thesis (Chapter 4 and Chapter 5), the limits of this versatile controlled radical polymerization process were examined under various conditions. Specifically, in Chapter 4, the photoinduced Cu-mediated polymerization of different acrylates in a continuous flow reactor was investigated without conventional deoxygenation, hence providing a simplification of the existing continuous flow approaches. Upon optimization, well-defined poly(acrylates) were synthesized with a range of molar masses and low dispersity values. Importantly, although in continuous flow and in the presence of air/oxygen, the synthesized polymers exhibited high end-group fidelity, as confirmed through efficient post polymerization modification. The oxygen tolerant nature of Cu-RDRP was further examined in Chapter 5, this time in batch and with the use of a bio-renewable solvent (CyreneTM), along with the use of very low catalyst loadings. Well-defined polymers with good macromolecular characteristics were obtained, providing an environmentally-friendly alternative synthetic way

Case Report - Intraspinal air after blunt thoracic trauma

Presence of intraspinal air (pneomorachis) is usually iatrogenic after epidural injections or spinal manipulations. It may also be associated with degenerative disc disease, epidural abscess and synovial cysts. Presented herein is a case of a child with pneomorachis following blunt thoracic trauma

Photo-induced copper-RDRP in continuous flow without external deoxygenation

Photo-induced Cu-RDRP of acrylates in a continuous flow reactor without the need for deoxygenation or externally added reagents. Optimization of the catalyst concentration and the flow rate/residence time leads to well-defined polyacrylates with controlled molecular weights, excellent initiator efficiency, high end-group fidelity polymers and product uniformity. A multifunctional initiator was also used to demonstrate the versatility of the system

Intraspinal air after blunt thoracic trauma

Presence of intraspinal air (pneomorachis) is usually iatrogenic after epidural injections or spinal manipulations. It may also be associated with degenerative disc disease, epidural abscess and synovial cysts. Presented herein is a case of a child with pneomorachis following blunt thoracic trauma