Linear Block Copolymer Synthesis

Abstract

Block copolymers form the basis of the most ubiquitous materials such as thermoplastic elastomers, bridge interphases in polymer blends, and are fundamental for the development of high-performance materials. The driving force to further advance these materials is the accessibility of block copolymers, which have a wide variety in composition, functional group content, and precision of their structure. To advance and broaden the application of block copolymers will depend on the nature of combined segmented blocks, guided through the combination of polymerization techniques to reach a high versatility in block copolymer architecture and function. This review provides the most comprehensive overview of techniques to prepare linear block copolymers and is intended to serve as a guideline on how polymerization techniques can work together to result in desired block combinations. As the review will give an account of the relevant procedures and access areas, the sections will include orthogonal approaches or sequentially combined polymerization techniques, which increases the synthetic options for these materials.

Polyphosphinoborane Block Copolymer Synthesis Using Catalytic Reversible Chain‐Transfer Dehydropolymerization

“…Complex 2, at least at the early stages of catalysis, is thus identified as a likely resting state. Following reaction progress by 1 H NMR spectroscopy at 100 °C (3 mol% 1), using the distinctive PÀ H resonances between 5.5 and 3.5 ppm, reveals a first order decay of ). In a separate experiment (3 mol% 1) using H 3 B • PPhHBH 2 • PPhH 2 (0.14 M) as the precursor resulted in its clean first order consumption (k obs = 1.0(1) × 10 À 4 s À 1 ) to form [H 2 BPPhH] n (M n = 61 000 g mol À 1 , Ð = 1.3 [40] ) with no H 3 B • PPhH 2 observed to the detection limit of 1 H NMR spectroscopy, indicating that depolymerization to H 3 B • PPhH 2 is not significant (Figure S23).…”

“…Complex 2, at least at the early stages of catalysis, is thus identified as a likely resting state. Following reaction progress by 1 [40] ) with no H 3 B • PPhH 2 observed to the detection limit of 1 H NMR spectroscopy, indicating that depolymerization to H 3 B • PPhH 2 is not significant (Figure S23). Combined these observations on the resting state and the temporal evolution of substrates and products lead us to propose a simplified mechanism, Scheme 3C, which is based on previous, detailed, mechanistic studies using the closely related dehydrocoupling of secondary phosphineboranes.…”

“…In situ catalyst speciation studies (3 mol% 1, 0.25 M H 3 B • PRH 2 ) using 31 P{ 1 H} NMR spectroscopy showed that in all cases (H 3 B) 2 • dppe is formed immediately (δ 18.7 [41] ) alongside free PRH 2 , demonstrating loss of dppe in the active catalyst. Focusing on H 3 B • PPhH 2 in the early stages of catalysis (10 mins, 23 % conversion of monomer) 1 H NMR spectroscopic analysis of the hydride region showed broad environments centered at δ À 1.9 and δ À 14.2 in a 3 : 1 relative integral respectively. Repeating at 10 mol% 1 for improved signal intensity, revealed more than one resonance in each chemical shift range, and that only the relative integral 3 H signal sharpened on decoupling 11 B, identifying these signals as being due to Rh•••H 3 B and RhÀ H respectively.…”

“…Organic block copolymers (BCPs), in which chemicallydistinct segments of monomer units are linked together in a polymer chain, have played an important role in the development of macromolecular science. [1][2][3][4] The solid-state and solution self-assembly behavior of BCPs has led to technologically-important ordered nanostructures, [5] such as films containing phase-separated nanodomains and micelles. Self-assembled BCPs have found a variety of applications which include nanolithography, high-performance additives, and delivery agents in biomedicine.…”

Advances on Controlled Chain Walking and Suppression of Chain Transfer in Catalytic Olefin Polymerization

“…The generated macroinitiators can start diverse polymerization techniques to form diblock copolymers. A recent review on discussing the linear block copolymer synthesis can be referenced …”