Conjugated Polymer Nanoparticles in Aqueous Media by Assembly with Phospholipids via Dense Alkyl Chain Packing

Abstract

Revealing the nature of chain packing in conjugated polymer nanoparticles (CPNs) is one of the important issues to polymer physics research. Surfactant-stabilized CPNs in water show significantly enhanced luminescence intensity in comparison to small molecular organic dyes and single polymer chains dissolved in solvents. The importance of the conjugated polymer structure in nanomaterials is undoubted. However, details of the relationship between alignment of conjugated polymer backbone in CPNs and its luminescent property have not been established. Furthermore, there are yet no methods that can predict the atom-resolved structure of conjugated polymer in the CPNs. Herein, we employ coarse-grained (CG) molecular dynamic simulations to investigate the structure of phase-separated film and the film shattering process for a mixture of poly­[2,6-(4,4-bis­(2-ethylhexyl)-4H-cyclopenta­[2,1-b;3,4-b′]-dithiophene)-alt-4,7-(2,1,3-benzo­thiadiazole)] (PCPDTBT) and 1,2-dioctanoyl-sn-glycero-3-phosphocholine (D8PC). The π–π stacked structure of PCPDTBT is significantly enhanced when the ratio of D8PC increases in both dried and water exposed film. We also show that the amount of D8PC is at least 2.5 times larger than that of PCPDTBT to wrap the conjugated polymer chain, and the direct retrieval of atomistic details is achieved through back-mapping from the morphology of CG. Finally, we confirmed that conjugated backbones inside the nanoparticles were completely shielded from the aqueous solution by the dense layers of alkyl chains, resulting in remarkably enhanced chain packing. These simulated results are correlated with experimentally observed structure through UV–vis–near-infrared (UV-vis-NIR) spectrometry, scanning electron microscopy (SEM), particle size analyzer (PSA), transmission electron microscopy (TEM), and grazing-incidence X-ray diffraction (GIXD).

Thienoisoindigo-Based Semiconductor Nanowires Assembled with 2-Bromobenzaldehyde via Both Halogen and Chalcogen Bonding

“…Such absorbance enhancement of the TIIG-Bz/2-BBA in the NIR region of the spectra was clearly shown even after excluding any scattering effect by measuring the spectra with an integrating sphere. The higher absorbance of the TIIG-Bz wires assembled with 2-BBA in the NIR region was consistent with our recent results of density functional theory calculations for conjugated polymer nanoparticles 54 , 55 . Such a red shift in the absorption spectra originates from enhanced intermolecular π − π interactions with energy level adjustments, and has been widely observed in thin films for organic optoelectronic devices or nanomaterials of conjugated polymers 56 – 61 .…”

Formation of nanopores in DiynePC–DPPC complex lipid bilayers triggered by on-demand photo-polymerization

“…The use of coarse-grained (CG) MD simulation enables examination of processes occurring at longer time scales, such as membrane domain formation, protein aggregation and structural packing properties. 20,21 The phase transition from uidic to gel phase and polymerization-induced pore generation in the supported DPPC bilayers containing pore-opening diacetylenic lipid are discussed.…”

Machine-Washable Smart Textiles with Photothermal and Antibacterial Activities from Nanocomposite Fibers of Conjugated Polymer Nanoparticles and Polyacrylonitrile

“…The absorption spectrum of the CPNs (Figure 1d) shows that the absorption maximum of the PCPDTBT assembled in the CPNs is significantly red-shifted to 796 nm in comparison to that of the PCPDTBT dissolved in the chloroform (717 nm). The 79 nm of bathochromic shift in the absorption spectrum was attributed to the intermolecular electronic delocalization between the backbones of the PCPDTBT in the CPNs, as demonstrated in the films and PCPDTBT films and nanoparticles used for the photovoltaic cell and biomedical fields [33,34,35]. This result indicates that the PCPDTBT backbones are closely associated in CPNs, resulting in a prominent enhancement in NIR absorption.…”