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

Abstract

This review explores the different synthetic methods by which dispersity and MWD shape can be tuned and discusses the different properties and applications where this variation is beneficial.

Precise modulation of molecular weight distribution for structural engineering

“…Technically, two approaches are usually adopted to modulate molecular weight distribution. 20 One is to control the polymerization process. The development of living/ controlled polymerization makes complicated molecular design and "narrow" molecular weight distribution possible.…”

Polymers in the Blender

“…[10] For self-assembly in solution, Eisenberg had shown that bimodal distributions can influence the shape of nanoaggregates. [11] More examples like this exist in literature (the reader is referred to ref [12] for details), hence showing the validity of the concept and the value of further exploration of the synthetic access to such materials.…”

“…[15] Yet, first very promising advances have been made toward controlling the broadness of molecular weight distributions. [12] Figure 1 summarizes the four principle pathways that may be chosen to achieve such aim. Varying dispersities can be accessed from RDRP (and in part from anionic polymerization) via i) direct manipulation of the control equilibrium governing the growth process, ii) via applying a specific initiation profile over the cause of a polymerization, by iii) arbitrary machine-learning methods and last but not least iv) blending of different polymer samples post-polymerization.…”

“…Atom transfer radical polymerization (ATRP), gives some more possibilities since activation and deactivation are bimolecular reactions, and the control equilibrium can thus be tuned via the relative concentrations of involved copper species. [12] Anastasaki was the first to realize this potential when tuning the dispersity of polymers made from photoATRP toward broader distributions. [19] Simply by changing the amount of Cu(II) (which is also used to generate Cu(I) from light activation) the equilibrium can be shifted, and polymers with constant molecular weight, but different dispersity become available.…”

Tailor-made thermoplastic elastomers: customisable materials via modulation of molecular weight distributions

“…12,13 Furthermore, there have been various reports on the inuence of block length and Đ on polymer microphase behaviour, which has a direct inuence on bulk properties. [14][15][16][17][18][19] While these reports provide important information regarding the inuence of block size and midblock MWD breadth on elastomeric properties, there remains an opportunity to use the entire endblock MWD shape as a means to ne-tune TPE properties.…”