Synthesis of a Bifunctional Initiator for Controlled Kumada Catalyst-Transfer Polycondensation/Nitroxide-Mediated Polymerization and Preparation of Poly(3-hexylthiophene)−Polystyrene Block Copolymer Therefrom

Abstract

Herein, we present a new approach to synthesize rod−coil block copolymers via consecutive Kumada catalyst-transfer polycondensation (KCTP) and nitroxide-mediated free radical polymerization (NMP) performed from a bifunctional initiator, TIPNO−Ph−Ni(dppp)−Br (TIPNO = 2,2,5-trimethyl-4-phenyl-3-azahexane-3-nitroxide; dppp = propane-1,3-diylbis(diphenylphosphane). The utility of the method was exemplified in a preparation of a model block copolymer, poly(3-hexylthiophene)-block-polystyrene (P3HT-b-PS) with a relatively narrow molecular weight distribution of 1.33. Synthesis of the bifunctional initiator was accomplished by a reaction of diethylbipyridylnickel with a readily accessible precursor, TIPNO−Ph−Br, followed by in situ replacement of the bipyridyl ligand onto bidentate phosphorus one.

Kumada Catalyst‐Transfer Polycondensation: Mechanism, Opportunities, and Challenges

“…Thus, the Et 2 Ni(bipy)-based external initiation is probably the most versatile approach among the reported schemes for the ex situ preparation of Ni initiators to date, as it is widely applicable, does not require the incorporation of stabilizing groups, and since its applicability was already demonstrated by the synthesis of well-defined CP architectures, e.g., spherical brushes, [46] star polymers, [73] and rod-coil block copolymers. [77] However, Et 2 Ni(bipy) is not commercially available and is highly reactive toward moisture and oxygen, making it difficult to handle. We were therefore interested in easily available and environmentally stable Ni precursors for the preparation of functional initiators.…”

Synthesis and Characterization of Poly(3-hexylthiophene)-b-Polystyrene for Photovoltaic Application

“…The synthetic routes are mainly categorized into two types. One is a macroinitiator method where one or both terminal(s) of P3HT were modified to initiating end groups followed by living polymerizations such as atom transfer radical polymerization (ATRP) [19], nitroxide-mediated polymerization (NMP) [20,21], and reversible addition fragmentation chain transfer polymerization (RAFT) [21]. The other is a coupling method which is based on the coupling reaction between living polystyryl anion and end-functionalized P3HT [22,23].…”

Polystyrene‐Based C60 Acceptor Copolymers through Azide–Alkyne Click Chemistry Approaches

“…To face this challenge, end capping of the fi rst block is a popular method to introduce initiating groups for nitroxide-mediated radical polymerization (NMRP), [19][20][21] reversible additionfragmentation chain transfer (RAFT), [ 18 , 22,23 ] atom transfer radical polymerization (ATRP), [ 16 , 24,25 ] or anionic polymerization. [ 26 ] Another approach was chosen by Kiriy and co-workers, [ 27 ] who polymerized P3HT with a bifunctional initiator, allowing to grow the second block from the "starting" group without further postpolymerization/ modifi cations.…”