Straightforward Synthesis of Conjugated Block Copolymers by Controlled Suzuki–Miyaura Cross-Coupling Polymerization Combined with ATRP

Abstract

Catalytic chain growth Suzuki−Miyaura polymerization of an AB-fluorene monomer using isolated (Ini1) or in situ generated (Ini2) Phos-Ph-Pd( t Bu 3 P)Br as an initiator afforded well-defined heterodifunctional polyfluorenes featuring a phosphonate group (initiating chain end) and a radically polymerizable (Phos-PF8-Sty) or atom transfer radical polymerization (ATRP)-initiating (Phos-PF8-AlkylBr) group (terminating chain end). The resulting Phos-PF8-AlkylBr polymer was directly employed for the growth of a second nonconjugated block by controlled activators regenerated by electron transfer ATRP without the need for further intermediate conversion steps. The PF8 macroinitiator was found to be a viable initiator for the generation of narrowly distributed diblock copolymers with a controlled block length of PF8 and polystyrene, poly(methyl methacrylate), or poly(2-ethylhexyl methacrylate), respectively. Novel conjugated nonconjugated comb polymers were generated by controlled radical copolymerization of PF8 macromonomers, bearing a styrene end group, with styrene or methacrylates. Thereby, it was possible to tune the number of phosphonate moieties per chain between 2 and 15.

The block copolymer shuffle in size exclusion chromatography: the intrinsic problem with using elugrams to determine chain extension success

“…Hence, in the case of a BCP, signals corresponding to different blocks but correlating to the same diffusivity prove that the blocks are indeed connected. [63][64][65][66] A decrease in the diffusion coefficient in comparison with the homopolymers or macroinitiator allows for a qualitative evaluation of an increase in the molecular weight. Loo et al exploited DOSY analysis for mapping the actual molecular weight distribution.…”

Strategies for the synthesis of water-soluble conjugated polymers

“…Many publications reported the polymerization of phosphonic esters using Suzuki or Negishi crosscoupling [76][77][78], sometimes followed by a deprotection using trimethylsilyl bromide [79][80][81]. For instance, a phosphonic ester can be polymerized and then deprotected to lead to a phosphonate group, thus allowing the water solubility [82].…”

Pairing Suzuki–Miyaura cross-coupling and catalyst transfer polymerization

“…This catalyst system has been successful for the controlled polymerization of polythiophenes, polyfluorenes, and various polyphenylenes. 25,[36][37][38]43,45,[48][49][50][52][53][54][55][57][58][59] The success of t Bu 3 P-Pd has led to investigations to prepare more exotic polymers such as poly(3,6-phenanthrene), 54 poly(fluorene-altbenzothiadiazole), 58 and poly( pyridyl-alt-thiophene). 113 For poly(fluorene-alt-benzothiadiazole), Huck and coworkers were able to bring about controlled chain-growth polymerization of this large monomer system, though molecular weights were modest (3-7.3 kg mol −1 ).…”