Copper-Mediated Polymerization without External Deoxygenation or Oxygen Scavengers

As a method for overcoming the challenge of rigorous deoxygenation in copper‐mediated controlled radical polymerization processes [e.g., atom‐transfer radical polymerization (ATRP)], reported here is a simple Cu0‐RDRP (RDRP=reversible deactivation radical polymerization) system in the absence of external additives (e.g., reducing agents, enzymes etc.). By simply adjusting the headspace of the reaction vessel, a wide range of monomers, namely acrylates, methacrylates, acrylamides, and styrene, can be polymerized in a controlled manner to yield polymers with low dispersities, near‐quantitative conversions, and high end‐group fidelity. Significantly, this approach is scalable (ca. 125 g), tolerant to elevated temperatures, compatible with both organic and aqueous media, and does not rely on external stimuli which may limit the monomer pool. The robustness and versatility of this methodology is further demonstrated by the applicability to other copper‐mediated techniques, including conventional ATRP and light‐mediated approaches.ISSN:1433-7851ISSN:1521-3773ISSN:0570-083

Sequence-Controlled Methacrylic Multiblock Copolymers: Expanding the Scope of Sulfur-Free RAFT

Sulfur-free reversible addition–fragmentation transfer polymerization (SF-RAFT) in emulsion allows access to the synthesis of sequence-controlled methacrylic multiblock copolymers. Herein, we expand the scope of SF-RAFT emulsion polymerization by utilizing four different macrochain transfer agents (mCTA) to mediate the synthesis of diblocks and sequence-controlled methacrylic multiblock copolymers. Poly­(methyl methacrylate) (pMMA), poly­(butyl methacrylate) (pBMA), poly­(ethyl methacrylate) (pEMA), and poly­(benzyl methacrylate) (pBzMA) of a similar <i>M</i>_n (∼4300 g mol^–1) were successfully synthesized via catalytic chain transfer polymerization (CCTP) in emulsion. The capability of these mCTAs to act as macroinitiators was investigated through the synthesis of “<i>in situ</i>” diblock copolymers and was then expanded to the synthesis of deca- and hexablock multiblock copolymers with varying degrees of polymerization (DP_n = 10–50 per block, <i>M</i>_n,total = 7000–55 000 g mol^–1), yielding well-defined copolymers with controlled molecular weights, quantitative conversions (>99%), and low dispersities (<i>Đ</i> ∼ 1.2) without employing sulfur or transition metal reagents

An evaluation of supported employment initiatives for disabled people

SIGLEAvailable from British Library Document Supply Centre-DSC:GPE/3338 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Sequence-controlled methacrylic multiblock copolymers via sulfur-free RAFT emulsion polymerization

Translating the precise monomer sequence control achieved in nature over macromolecular structure (for example, DNA) to whole synthetic systems has been limited due to the lack of efficient synthetic methodologies. So far, chemists have only been able to synthesize monomer sequence-controlled macromolecules by means of complex, time-consuming and iterative chemical strategies such as solid-state Merrifield-type approaches or molecularly dissolved solution-phase systems. Here, we report a rapid and quantitative synthesis of sequence-controlled multiblock polymers in discrete stable nanoscale compartments via an emulsion polymerization approach in which a vinyl-terminated macromolecule is used as an efficient chain-transfer agent. This approach is environmentally friendly, fully translatable to industry and thus represents a significant advance in the development of complex macromolecule synthesis, where a high level of molecular precision or monomer sequence control confers potential for molecular targeting, recognition and biocatalysis, as well as molecular information storage