Facile synthesis of hyperbranched poly(p‐phenyleneethynylene‐alt‐m‐phenyleneethynylene) with narrow dispersity and high branching degree by sonogashira polymerization of an AB₂ monomer

Abstract

An AB 2 monomer PhBr 2 ACBCAPhACBCH containing one acetylene group and two bromide groups was efficiently synthesized by a strategy based on the different reactivity between aromatic iodide and bromide in Sonogashira reaction. The Sonogashira polymerization of PhBr 2 ACBCAPhACBCH was investigated to get hyperbranched poly(p-phenyleneethynylene-alt-mphenyleneethynylene) (hb-PMPE) in terms of the effects of monomer addition method, core molecule with different functionality, and ratio of INTRODUCTION Because of the highly branched and globular structure, hyperbranched conjugated polymers exhibit better solubility, thermal stability, and processibility than their linear analogues; therefore, it is much easier for them to form amorphous films of high quality and morphological stability. Moreover, the hyperbranched structure can enhance exciton confinement, suppress intrachain and interchain exciton annihilation, thereby, improve fluorescence quantum yields and electroluminescent efficiency significantly. 1 The global molecular shape can also induce efficient intramolecular energy transfer. [2][3][4] Hyperbranched conjugated polymers have attracted considerable attention as novel materials in the fields of light emitting, 5-23 solar cells, 24-26 fluorescent chemosensors, 27-32 and so on.

Synthesis of Nano-Structured Conjugated Polymers with Multiple Micro-/Meso-Pores by the Post-Crosslinking of End-Functionalized Hyperbranched Conjugated Polymers

“…No signal of -C≡CH can be observed, indicating the complete conversion of -C≡CH. As reported in a previous paper on the synthesis of hyperbranched poly (m-phenyleneethynylene-alt-p-phenyleneethynylene) (hb-PMPE) [25], the signal of -OCH 2 -in dendritic (D), terminal (T), and linear (L) units of hb-PMPE can be distinguished as three separated peaks within the range of δ 4.0~4.4 ppm in the 1 H NMR spectrum, since the chemical environment of the alkoxyl group in D, T, and L units of hb-PMPE is different from each other: in the D unit, both the two o-substituent groups of alkoxyl are ethynylene groups; in the T unit, both the two o-substituent groups of alkoxyl are bromide groups; while in the L unit, one o-substituent group is ethynylene and another is bromide. Therefore, the branching degree (DB) of hb-PMPE can be calculated from the 1 H NMR spectrum by the integration of these three peaks.…”

“…Compound 1 [25] and Compound 2 [26] were synthesized by the procedures in the literature, respectively.…”

“…As shown in Scheme 1, an AB2-type monomer The monomer PECz was polymerized by the Sonogashira reaction to give the hyperbranched conjugated prepolymer hb-PPECz. For the polymerization of ABn monomer to give hyperbranched polymer, core molecules were usually added to control the product's molecular weight by varying the molar ratio of [ABn monomer]/[core molecule] and obtain a narrower molecular weight distribution [25]. Therefore, 1,4-diiodolbenzene was added as the core molecule.…”

π-Face strapped monomers enable self-stabilized hyperbranched π-conjugated polymer particles

“…Solution processable hyperbranched conjugated polymers have been synthesized using repeat units that contain pendant solubilizing chains. 21,24,27,28 However, solution soluble hyperbranched polymers without the pendant solubilizing chains are not known to the best of our knowledge. The nearest systems to the hyperbranched conjugated polymers without pendant solubilizing chains are conjugated (porous) polymer networks.…”

“…Alternative synthetic strategies, such as using non-stoichiometric monomer feed ratios and using synthetically demanding AB 2 type monomers in conjunction with pendant alkyl chains, have shown success in producing soluble low molecular weight π-conjugated HBPs. 15,26–28 Although some progress has been made in synthesizing solution-processable conjugated HBPs by mitigating interchain interactions through interarylene torsion angles and pendant solubilizing chains, 19,29–31 there remains a critical need for strategies that directly target the interchain π–π stacking interactions at the molecular level, enabling control over the growth and processability of π-conjugated HBPs.…”