Grafting of poly(3-hexylthiophene) brushes on oxides using click chemistry

Abstract

Poly(3-hexylthiophene) (P3HT) brushes on silicon dioxide (SiO 2 ) were prepared using a click reaction between ethynyl-terminated P3HT and an azide self-assembled monolayer (SAM). Regioregular ethynyl-terminated P3HT with molecular weight of 5900 g mol À1 and polydispersity of 1.2 was synthesized by catalyst-transfer polycondensation using Grignard metathesis mediated by a nickelbased catalyst. The azide SAM was prepared from bifunctional molecules containing azide and siloxane as click reaction precursor and surface linker, respectively. The P3HT brushes were characterized by atomic force microscopy, ellipsometry, X-ray photoelectron spectroscopy, infrared reflection absorption spectroscopy, and UV-visible spectroscopy. The grafting of P3HT brushes was studied as a function of click reaction time and the growth of the brushes is governed by a diffusioncontrolled process. P3HT brushes were prepared on pre-fabricated field-effect transistor structures in order to probe the electrical properties of the brushes. The versatile synthetic methodology developed in this work can be generalized to prepare a wide variety of semiconducting conjugated polymer brushes on oxide surfaces relevant to organic electronic devices.

“Click” polymerization: A convenient strategy to prepare designer fullerene materials

“…Azidopropyltrimethoxysilane was prepared from combination of (3-chloropropyl)trimethoxysilane and sodium azide using literature procedure [18]. 5,5'-diethynyl-2,2 bithiophene(1) was freshly prepared from 5,5'-dibromo-2,2'-bithiophene following the method described by Wong and others [19].…”

From Self-Assembled Monolayers to Coatings: Advances in the Synthesis and Nanobio Applications of Polymer Brushes

“…More recently "Click" chemistry has been used to form polymer brushes with high grafting efficiency, minimized side reactions and to provide relatively mild reaction conditions which avoid any photochemical or thermal degradation of chemical functionalities [67,[78][79][80][81][82]. Paoprasert et al showed that Cu(I)-catalyzed Huisgen 1,3-dipolar cycloaddition of azide group with alkyne group was an efficient route to form conducting polymer brushes with controlled film thickness and chain density (Figure 4a) Figure 4b) [83,84].…”

“…Conventionally, XPS has been used to determine the absolute surface concentration of a particular element by integrating the intensity ratio of the element in the SAMs to that of an element in the underlying substrate, where atomic density is known [78,147]. For an ATRP initiator containing surface, contributions from the emitted electrons in three different layers to the net signal has been analyzed: Electrons emitted from elements (C, O and Br) from initiator containing organic layer, electrons emitted from silicon atoms from the native oxide layer and electrons emitted from silicon atoms in the silicon substrate (Figure 10).…”

Benzodithiophene-based low band-gap polymers with deep HOMO levels: synthesis, characterization, and photovoltaic performance

“…BDT1, 21,22 BDT2, 23,24 Th1, 25,26 Th2 27 and 2,5-dibromo-3-hexylthiophene (Th3) 28 were synthesized according to previously published protocols.…”