Tuning Dispersity by Photoinduced Atom Transfer Radical Polymerisation: Monomodal Distributions with ppm Copper Concentration

Abstract

Dispersity significantly affects the properties of polymers. However, current methods for controlling the polymer dispersity are limited to bimodal molecular weight distributions, adulterated polymer chains, or low end‐group fidelity and rely on feeding reagents, flow‐based, or multicomponent systems. To overcome these limitations, we report a simple batch system whereby photoinduced atom transfer radical polymerisation is exploited as a convenient and versatile technique to control dispersity of both homopolymers and block copolymers. By varying the concentration of the copper complex, a wide range of monomodal molecular weight distributions can be obtained (Đ=1.05–1.75). In all cases, high end‐group fidelity was confirmed by MALDI‐ToF‐MS and exemplified by efficient block copolymer formation (monomodal, Đ=1.1–1.5). Importantly, our approach utilises ppm levels of copper (as low as 4 ppm), can be tolerant to oxygen and exhibits perfect temporal control, representing a major step forward in tuning polymer dispersity for various applications.

Tailoring polymer dispersity and shape of molecular weight distributions: methods and applications

“…4). 73 Signicantly, very low ppm levels of copper catalyst (as low as 4 ppm) enabled perfect temporal control in photoinduced ATRP, which contrasts previous reports in organic media. 69,74 The resulting materials exhibit exceptional endgroup delity, capable of chain extension with negligible termination.…”

“…Additionally, control over the MWD was also achieved in the absence of any external deoxygenation 75,76 (using the so-called oxygen tolerant approach) although lower initiator efficiencies were reported. 73 An equation has been derived which illustrates the relationship between the catalyst concentration and the dispersity of the polymers generated. 77 The dispersity also correlates with the relative rates of propagation and deactivation, the conversion and the degree of polymerisation.…”

“…Reactions also don't reach high conversions and therefore isolation of a macroinitiator is required if block copolymers are to be prepared. 73 There are also no examples in the literature, where the shape of the MWD has been controlled by changing the catalyst concentration.…”

Bright Science Award:M. Hillmyer / Hanwha‐Total IUPAC Awards:A. Anastasaki und C. Chen

“…Anastasakis Gruppe entwickelt neue Methoden in der radikalischen Polymerisation, mit dem Ziel, Molekulargewicht, Dispersität, Architektur, Funktionalität und Selbstorganisation der polymeren Materialien zu steuern. In Zuschriften in der Angewandten Chemie beschrieb sie, wie man die Dispersität duch photoinduzierte radikalische Atomtransferpolymerisation vorgibt und wie eine kupfervermittelte Polymerisation ohne externe Desoxygenierung oder Sauerstofffänger gelingt . Anastasaki gehört dem Redaktionsbeirat des Journal of Polymer Science an.…”

Bright Science Award: M. Hillmyer / Hanwha‐Total IUPAC Awards: A. Anastasaki and C. Chen

“…Anastasaki's group develops new methods in radical polymerization to control molecular weight, dispersity, architecture, functionality, and self‐assembly of polymeric materials. In Communications in Angewandte Chemie she described dispersity tuning by photoinduced atom‐transfer radical polymerisation and a copper‐mediated polymerization without external deoxygenation or oxygen scavengers . Anastasaki is on the Editorial Board of the Journal of Polymer Science .…”