The limits of precision monomer placement in chain growth polymerization

Abstract

Precise control over the location of monomers in a polymer chain has been described as the ‘Holy Grail' of polymer synthesis. Controlled chain growth polymerization techniques have brought this goal closer, allowing the preparation of multiblock copolymers with ordered sequences of functional monomers. Such structures have promising applications ranging from medicine to materials engineering. Here we show, however, that the statistical nature of chain growth polymerization places strong limits on the control that can be obtained. We demonstrate that monomer locations are distributed according to surprisingly simple laws related to the Poisson or beta distributions. The degree of control is quantified in terms of the yield of the desired structure and the standard deviation of the appropriate distribution, allowing comparison between different synthetic techniques. This analysis establishes experimental requirements for the design of polymeric chains with controlled sequence of functionalities, which balance precise control of structure with simplicity of synthesis.

Coding and decoding libraries of sequence-defined functional copolymers synthesized via photoligation

“…Although these advances of limiting the statistical nature of polymerization processes are impressive and led to fine examples of sequence-controlled polymers711131516, only few sequence-defined examples have been reported that reach the precision level of nature25. Directly inspired by biologically accessible DNA systems—for example, nucleobase-coded chains—sequence-defined macromolecules have been synthesized employing template-based coding strategies26272829 or via the generation of regulated sequence alternating thymine hybrid polymers30, as well as the design of reactions with iterative protection/deprotection steps on supports3132.…”

A Breathing Atom‐Transfer Radical Polymerization: Fully Oxygen‐Tolerant Polymerization Inspired by Aerobic Respiration of Cells

“…This suggested the generation of new chains from H 2 O 2 produced by GOx, continued even in ac losed vial. [32] In some biological systems,s uch as in the aerobic respiration of cells,g lucose and oxygen after several enzyme-catalyzed reactions produce CO 2 and ATPmolecules. To prevent formation of new chains,t he reactive oxygen species should be eliminated and converted to inert products that do not interfere with propagating radicals or catalyst.…”

Sequence-controlled polymers via reversible-deactivation radical polymerization

“…This condition allows faster polymerization without a concomitant loss of living polymerization feature, and indeed the initiator with a lower 10-h half-life decomposition temperature (44°C in water) is almost fully decomposed in 2 h at 70°C. Although there is a problem with the accuracy regarding the number of inserted monomers due to the limitation by Poisson distribution, 18 an icosablock copolymer can be synthesized by repeating the addition of three equivalent monomers of various pendant groups 20 times. Similar multiblock copolymers of acrylates have been synthesized via aqueous single-electron transfer living radical polymerization 19 or Cu-mediated photopolymerization.…”