We developed an unconventional route to uniform and intimate semiconducting organic-inorganic nanocomposites for potential applications in thermoelectrics. Central to this strategy was the rational design and synthesis of amphiphilic star-like coil-rod diblock copolymer, poly(acrylic acid)-block-poly(3,4-ethylenedioxythiophene) (PAA-b-PEDOT) as nanoreactor. Such unimolecular micellar-like PAA-b-PEDOT comprising inner hydrophilic coil-like PAA blocks and outer hydrophobic rod-like PEDOT blocks was successfully prepared by a judicious combination of atom transfer radical polymerization (ATRP), quasi-living Grignard metathesis (GRIM) method, and click reaction. By capitalizing on amphiphilic star-like PAA-b-PEDOT diblock copolymer as nanoreactor, monodisperse PEDOT-functionalized lead telluride (PbTe) nanoparticles were crafted via the strong coordination interaction between PAA blocks of star-like PAA-b-PEDOT and the metal moieties of precursors (i.e., forming PEDOT-PbTe nanocomposites). As inner PAA blocks were originally covalently connected to outer PEDOT blocks, the PEDOT chains were intimately and permanently tethered on the PbTe nanoparticle surface, thereby affording elegantly defined PEDOT/PbTe interface, preventing PbTe nanoparticles from aggregation, and more importantly promoting the long-term stability of PEDOT-PbTe nanocomposites. The crystalline structure and morphology of nanocomposites were scrutinized by X-ray powder diffraction and transmission electron microscopy, respectively. We envision that the nanoreactor strategy is general and robust, and offers easy access to other exotic conjugated polymer-inorganic semiconductor nanocomposites for use in a variety of applications.

  April 2015: Hui's paper, "A general route to nanocrystal kebabs periodically assembled on stretched flexible polymer shish ", was published in Science Advances. Congratulations!!! Highlighted by:Science:"Crafting organic-inorganic shish-kebabs" and Georgia Institute of Technology:"Nanoscale "worms" provide new route to nano-necklace structures".

    We demonstrate an unconventional and general strategy for the in-situ synthesis of a variety of 1D inorganic nanonecklaces composed of periodically assembled, uniform nanocrystals with precisely controlled size and composition by using rationally designed amphiphilic unimolecular worm-like diblock copolymers poly(acrylic acid)-block-polystyrene (PAA-b-PS) as nanoreactors. First, nanoreactors are judiciously synthesized by sequential atom transfer radical polymerization (ATRP) of tert-butylacrylate (tBA) and styrene (St) from a polyrotaxane-based macroinitiator, yielding worm-like poly(tert-butylacrylate)-block-polystyrene (PtBA-b-PS), followed by the hydrolysis of PtBA into PAA (i.e., yielding PAA-b-PS). The polyrotaxane-based macroinitiator is virtually prepared by forming inclusion complex between α-cyclodextrin (α-CD) and linear polyethylene glycol (PEG). Subsequently, the preferential coordination interaction between metal moieties of precursors and functional groups of PAA in worm-like PAA-b-PS creates PS-capped inorganic nanonecklaces in which a wide range of regularly spaced disk-like nanocrystals (nanodisks), including semiconductor CdSe, magnetic Fe3O4 and ferroelectric BaTiO3, are threaded by the flexible yet stretched PEG chain. Quite intriguingly, as PEG acts as the central stem with nanodisks periodically grown on it, such linearly assembled nanonecklaces resemble organic-inorganic nanohybrid shish-kebabs. The nanodisks are oriented perpendicular to the PEG shish although the latter cannot be identified under transmission electron microscope (TEM) due to small size and low electron density. The average distance between adjacent nanodisk kebabs is 2 nm with an average size of nanodisk of 4 nm. In order to elucidate the mechanism governing the formation of nanonecklaces, simulations based on self-consistent field theory (SCFT) are performed, and the dimensions of nanonecklaces (i.e., diameter, thickness and spacing) from different samples are calculated, which are in substantial agreement with the experimental results.