This work reports on a synthetic strategy to generate poly(3-alkylthiophene)s (P3ATs) with jointsimultaneous control of the molar mass and the regioregularity. A series of chiral P3ATswith different regioregularities is synthesized using a Pd(RuPhos)-catalyzed chain-growth polymerisation. All polymers have molar masses and polydispersities (PDI) that lie within a narrow region. Furthermore, it is shown that the Pd-catalyst forms all kinds of couplings [head-to-tail (HT), tail-to-tail (TT) and head-to-head (HH)] to a similar extent, which allows to insert predictable amounts of regio-irregularities into the polymer chain. This enables a thorough study of the influence of the regioregularity on the properties of P3AT, which was performed using UV-vis and circular dichroïsm (CD) spectroscopy, differential scanning calorimetry (DSC) and atomic force microscopy (AFM) measurements. Unexpectedly, it is found that in "kinetic" conditions the highest crystallinity, π-stacking, supramolecular organisation and chiral expression are not obtained for fully regioregular P3AT with 100% HT couplings, but that a small amount of regio-irregularity increases these properties and the chiral expression. In "thermodynamical" conditions (after annealing, very slow solvent evaporation or very slow cooling from the melt), this effect is less pronounced or not found. This behaviour can be explained by a higher degree of motional freedom within the non-perfect polymer chains due to the increased steric repulsion from the HH-couplings, which leads to a more easy stacking in "kinetic" conditions.

This manuscript consists of two parts which focus on enhancing control over the polymerization of conjugated polymers. In the first part, the controlled chain-growth character of the polymerization of poly(selenophene) using Pd(Ruphos) as a catalyst system is demonstrated. Next, all-conjugated thiophene−fluorene−selenophene triblock-copolymers are synthesized in all possible orders using this catalyst. Subsequent, the properties of these advanced structures are assessed using GPC chromatography and 1 H NMR, UV−vis, and fluorescence measurements. DFT calculations were performed to explain the unusual independence of the monomer sequence during the polymerization, traditionally observed in other chain-growth protocols for conjugated polymers. ■ INTRODUCTIONπ-Conjugated polymers are well-studied materials during the last decades because of their optoelectronic properties and their potential in low-cost electronics resulting from their conductivity and easy processing. 1−10 The quest toward complex and tailored polymeric structures to improve the performance and usability was the topic of research in the recent past and continues nowadays. 11 This quest starts with obtaining as much control as possible over the polymerization mechanism, hereby turning it into a controlled chain-growth mechanism with control on end-group functionalization and molar masses. 12−15 Moreover, this enables block-copolymerization by successive monomer addition, in which the next monomer is added after the previous monomer is completely consumed. The research groups of McCullough and Yokozawa simultaneously discovered the chain-growth character of poly(3-hexylthiophene) with Ni(dppp)Cl 2 (dppp = diphenylphosphinopropane) as a catalyst. 16−19 Further research resulted also in control over other conjugated polymers that were formed in a chain-growth fashion using the same or other Ni-and Pd-based catalysts. 20−34 The controlled nature of the polymerization relies on the association of the catalyst with the π-system of the propagating polymer chain after the reductive elimination (catalyst-transfer polycondensation, CTP). 35 As a consequence, termination and transfer reactions are avoided and a controlled chain-growth polymerization mechanism is obtained. In principle, if the controlled polymerization of two different monomers is obtained under the same conditions, allconjugated block-copolymers (π-BCPs) are accessible by sequential monomer addition. Nevertheless, since the mechanism relies on the association of the catalyst with the propagating polymer, the synthetic direction is fixed from the monomer with the lowest catalyst affinity to the one with the highest catalyst affinity, as reported by the groups of Yokozawa and Wang. 30,32 As a consequence, the number of all-conjugated block-copolymers composed of electronically different blocks prepared by successive monomer addition remains scarce, e.g.

Conjugated graft copolymers consisting of a chiral poly(phenyleneethynylene) (PPE) backbone and poly(3-hexylthiophene) side-chains (P3HT) with different grafting degrees were synthesized. While PPE was prepared by classical Sonogashira couplings, the end-functionalized P3HT was prepared by a controlled Kumada catalyst transfer polycondensation (KCTP) allowing

Conjugated graft copolymers consisting of a poly(3‐hexylthiophene) (P3HT) backbone and poly(9,9'‐dioctylfluorene) side chains (PF) with different grafting degrees were synthesized by the CuAAC reaction. The properties of these materials were studied by UV‐Vis and fluorescence spectroscopy. The former technique provides insight in their self‐assembly, while the latter is used to study the energy funneling from the PF side chains to the P3HT backbone. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 1252–1258

In this contribution, we report the synthesis of chiral all‐conjugated branched poly(phenylene ethynylenes) with a controlled amount of branching. Subsequently, the self‐assembly of these PPEs is studied by means of UV–vis, fluorescence spectroscopy, and DSC and the influence of branching is investigated. Finally, CD‐spectroscopy is used to study the influence of branching and self‐assembly on the chiral expression of these polymers. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 79–84