POLY(STYRENE)-BLOCK-POLY(4-VINYLPYRIDINE)/MoS2 NANOCOMPOSITES: PREPARATION AND CHARACTERIZATION

Abstract

Self-assembly of block copolymers are of significant research interest. Amphiphilic copolymers having both hydrophilic and hydrophobic blocks are considered one of the most useful classes of nanomaterials because of their ability to self-assemble into different morphologies and subsequently template organic, inorganic, semiconducting, metallic or biologically relevant material nanopatterns. Block copolymers consisting of poly(vinylpyridine) segments in their structure are frequently used for the fabrication of various hybrid nanostructures, and polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) is probably one of the most explored polymers in this area. The ability of pyridine units to undergo hydrogen bonding and coordinate with electron-deficient species largely simplifies the functionalization process and diversifies synthetic strategies, which can be implemented to achieve desired materials which can be used in various applications such as water-soluble polymers and coordination reagents for transition metals.

Surprisingly, most of the literature reports related to PS-b-P4VP micellar systems have focused on either symmetric or asymmetric BCP compositions with longer PS block where the solution self-assembly was studied in PS-selective conditions. The PS-b-P4VP micellar systems comprising longer P4VP blocks are scarce and less explored. Recently, a controlled/living radical polymerization for the 4-vinylpyridine homopolymer and block copolymer has been reported using various methods. Although the synthesis of a 4-vinylpyridine contained block copolymer was reported, the study of using polystyrene-block-poly(4-vinylpyridine) to prepare composites with MoS2 has not been reported. These hybrids are particularly interesting since they inherit some of the properties of both the polymer and the inorganic materials, such as mechanical performance and magnetic and optical characteristics. In this study, poly(styrene)-b-poly(4-vinylpyridine), poly(4-vinylpyridine)-b-poly(styrene)-b-poly(4-vinylpyridine), homopolymers of polystyrene and poly(4-vinylpyridine) were successfully synthesized by living anionic polymerization (LAP) in one pot step. Then the synthesized polymers were used to prepare the nanocomposites with MoS2. The structural characterizations were carried out by FT-IR and NMR spectroscopy (1H NMR, 13C NMR). Thermal properties were studied by TGA and DSC. AFM was utilized to study the morphologies and self-assembly of the synthesized PS-b-P4VP and composites with MoS2.