Nano-Hybrids Based on Surface Modified Reduced Graphene Oxide Nanosheets and Carbon Nanotubes and a Regioregular Polythiophene

The multi-walled carbon nanotubes (CNTs) and reduced graphene oxide (rGO) nanosheets were functionalized with 2-hydroxymethyl thiophene (CNT-f-COOTh) and 2-thiophene acetic acid (rGO-f-TAA) and grafted with poly(3-dodecylthiophene) (CNT-g-PDDT and rGO-g-PDDT) to manipulate the orientation and patterning of crystallized regioregular poly(3-hexylthiophene) (P3HT). Distinct nano-hybrid structures including double-fibrillar (5.11−5.18 S/cm), shish-kebab (2.19−2.28 S/cm), and stem-leaf (6.96−7.51 S/cm) were developed using modified CNTs and P3HT. The most effective parameter on morphology of donor-acceptor supramolecules was the surface functionalization and grafting. The electrical conductivities of supramolecules based on P3HT and rGO, rGO-f-TAA, and rGO-g-PDDT ranged in 3.81−3.87, 3.91−3.95, and 10.67−10.70 S/cm, respectively. P3HT chains preferred to interact with their thiophene rings with bared rGO and CNT surfaces, resulting in a conventional face-on orientation. In P3HT/rGO-f-TAA and P3HT/CNT-f-COOTh supramolecular nanostructures patterned with P3HT, the orientation of P3HT chains changed from face-on to edge-on, originating from the strong interactions between the hexyl side chains of P3HTs and functional groups. Nano-hybrids based on grafted rGO demonstrated a patched-like morphology composed of flat-on P3HTs with main backbones perpendicular to the substrate. Based on the ultraviolet-visible and photoluminescence analyses, the flat-on orientation was the best for P3HT chains assembled onto CNT and rGO, which was acquired for CNT-g-PDDT and rGO-g-PDDT nano-hybrids

3D Scaffold Designing based on Conductive/Degradable Tetrapolymeric Nanofibers of PHEMA-co-PNIPAAm-co-PCL/PANI for Bone Tissue Engineering

The hydrophilic, conducting, biocompatible and porous scaffolds were designed using poly(2-hydroxy ethyl methacrylate)-co-poly(N-isopropylacrylamide)-co-poly(ε-caprolactone) (P(HEMA-b-NIPAAm-b-CL))/polyaniline (PANI) for the osteoblast applications. To this end, the PHEMA and P(HEMA-b-NIPAAm) were synthesized via reversible addition of fragmentation chain transfer (RAFT) polymerization, and in next step, the ε-caprolactone was polymerized from –OH group of PHEMA segments through the ring opening polymerization (ROP). The electroactivity, mechanical properties, and hydrophilicity of designed scaffolds played an important role in the adhesion, differentiation, and proliferation of MG63 cells. By using the PHEMA and PNIPAAm, the hydrophilicity and biocompatibility, and by employing the PCL, the appropriate mechanical properties were acquired. The addition of PANI in the composition induced the conductivity to scaffolds. The morphology, electrical conductivity, biocompatibility, hydrophilicity and mechanical characteristics of the nanofibers were thoroughly investigated. The scaffolds possessed a porous nanostructure (nanofiber diameter ranged in 60–130 nm) with a large surface area, electrical conductivity of 0.03 S cm–1 and contact angle of 49 ± 5 ͦ , which imitated the natural microenvironment of extra cellular matrix (ECM) to regulate the cell attachment, proliferation and differentiation. In vitro cytocompatibility studies were performed over 168 h and indicated that the nanofibers were non-toxic to MG63 cells and potent to the artificial nanostructured osteoblasting

Scattering Study of Conductive-Dielectric Nano/Micro-Grained Single Crystals Based on Poly(ethylene glycol), Poly(3-hexyl thiophene) and Polyaniline

Two types of rod-coil block copolymers including poly(3-hexylthiophene)-block-poly(ethylene glycol) (P3HT-b-PEG) and PEG-block-polyaniline (PANI) were synthesized using Grignard metathesis polymerization, Suzuki coupling, and interfacial polymerization. Afterward, two types of single crystals were grown by self-seeding methodology to investigate the coily and rod blocks in grafted brushes and ordered crystalline configurations. The conductive P3HT fibrillar single crystals covered by the dielectric coily PEG oligomers were grown from toluene, xylene, and anisole, and characterized by atomic force microscopy (AFM) and grazing wide angle X-ray scattering (GIWAXS). Longer P3HT backbones resulted in folding, whereas shorter ones had a high tendency towards backbone lamination. The effective factors on folding of long P3HT backbones in the single crystal structures were the solvent quality and crystallization temperature. Better solvents due to decelerating the growth condition led to a higher number of foldings. Via increasing the crystallization temperature, the system decreased the folding number to maintain its stability. Poorer solvents also reflected a higher stacking in hexyl side chain and π-π stacking directions. The dielectric lamellar PEG single crystals sandwiched between the PANI nanorods were grown from amyl acetate, and analyzed using the interface distribution function (IDF) of SAXS and AFM. The molecular weights of PANI and PEG blocks and crystallization temperature were focused while studying the grown single crystals

Scrolled/Flat Crystalline Structures of Poly(3-hexylthiophene) and Poly(ethylene glycol) Block Copolymers Subsuming Unseeded Half-Ring-Like and Seeded Cubic, Epitaxial, and Fibrillar Crystals

Three distinct types of poly­(3-hexylthiophene) (P3HT)-based crystals were developed using unseeded and seeded protocols. First, unseeded flat fibrillar and scrolled half-ring-like crystals were prepared by isothermal crystallization of homo-P3HT and P3HT-<i>b</i>-poly­(ethylene glycol) (PEG) block copolymers. Anisotropic accumulation of grafted coily PEG blocks on the opposite surfaces of P3HT half-rings having extended backbones reflected scrolling, and their subsequent crystallization also further intensified this scrolling. The PEGs assembled into lamellae on both sides of P3HT half-rings with dissimilar crystalline features, i.e., the outer PEG lamella was thicker (17.4 nm) and wider (23.1 nm) compared to the inner one (15.0 and 18.1 nm). Furthermore, the crystallinity of PEG coily blocks accumulated on the P3HT crystals did not change the extended state of P3HT backbones (17.5 nm) and also the thickness of half-rings (11.0 nm). Second, with seeding homogeneous P3HT₇₀₀₀-<i>b</i>-PEG₅₀₀₀ solution using homo-PEG₅₀₀₀ tiny crystals, the cubic PEG single crystals were sandwiched between grafted regioregular P3HT chains (>99%). The appearance of (020)_P3HT and (100)_P3HT spots for tethered P3HTs beside (120)_PEG prisms demonstrated flat-on orderly tethered P3HT backbones on the PEG single crystalline substrate. Via conjunction between block copolymer and homopolymer single crystals in channel (PEG)/wire (P3HT-covered PEG)/channel (PEG) epitaxials, the P3HT rigid brushes were found to be extended (17.35 nm) on lamellar PEG substrate (6.15 nm). Third, when homogenized P3HT₇₀₀₀-<i>b</i>-PEG₅₀₀₀ solutions were seeded by homo-P3HT₇₀₀₀ tiny crystals, the edge-on orientated fibrillar P3HT single crystals were acquired. Although the thickness (20–22 nm) and length (60–63 μm) of P3HT₇₀₀₀-<i>b</i>-PEG₅₀₀₀ fibrillar single crystals resembled those of homo-P3HT₇₀₀₀ ones, their backbone lamination in the <i>c</i> axis were significantly different (2 versus 21); because the P3HT backbones were not capable of laminating from the coily block sides

Arrangement of Conductive Rod Nanobrushes via Conductive–Dielectric–Conductive Sandwiched Single Crystals of Poly(ethylene glycol) and Polyaniline Block Copolymers

Conductive rod nanobrushes of polyaniline (PANI) were developed via the growth of conductive–dielectric–conductive sandwiched single crystals obtained from poly­(ethylene glycol) (PEG₅₀₀₀)-<i>b</i>-PANI_<i>n</i>, PANI_<i>n</i>-<i>b</i>-PEG₆₀₀₀-<i>b</i>-PANI_<i>n</i>, and PANI_<i>n</i>-<i>b</i>-PEG₃₅₀₀₀-<i>b</i>-PANI_<i>n</i> block copolymers synthesized by interfacial polymerization fostering two different oxidants (ammonium peroxydisulfate (APS) as a weaker and potassium hydrogen biiodate (PHD) as a stronger oxidant). Based on the dispersity of the diameter of the PANI nanofibers and the various molecular weights of PEG substrates, two distinct morphologies were detected, i.e., matrix–dispersed morphology for PANI_<i>n</i>-<i>b</i>-PEG₃₅₀₀₀-<i>b</i>-PANI_<i>n</i> and dispersed–dispersed morphology for PANI_<i>n</i>-<i>b</i>-PEG₆₀₀₀-<i>b</i>-PANI_<i>n</i> and PEG₅₀₀₀-<i>b</i>-PANI_<i>n</i> single crystals. In matrix–dispersed single crystals, through an elevated crystallization temperature (<i>T</i>_c), a convergence occurred between the heights of matrix (partly stretched PANIs) and disperses (fully stretched PANIs). Because of their higher conductivity (e.g., 3 vs 10^–4 S/cm for copolymers and 84 vs 8 × 10^–3 S/cm for corresponding homopolymers), the variation in height between the matrix and disperses was lower in PHD-synthesized PANI nanofibers (e.g., height variance of 2 nm for PHD-synthesized PANI₁₈₀ vs 57 nm for APS-synthesized PANI₁₇₅ at <i>T</i>_c = 38 °C). The diameter of the dispersed PANI was inversely proportional to the crystallization temperature and was directly proportional to the PANI repeating units. Although in PEG₃₅₀₀₀-based systems PANI-dispersed diameters of up to 58 nm were detected in PANI₁₀₉-<i>b</i>-PEG₇₉₅-<i>b</i>-PANI₁₀₉ single crystals at <i>T</i>_c = 18 °C due to a scarcity in the provided surface area, the maximum diameters included in PEG₆₀₀₀ and PEG₅₀₀₀ single crystals were 9 and 7 nm, respectively. In dispersed–dispersed morphologies, having extended conformation of PANI brushes on PEG₅₀₀₀ and PEG₆₀₀₀ substrates, their substrate thickness did not vary by the lengthening of the PANI brushes, and the only effect oxidant had in these systems was on the population of grown single crystals; that is, the weaker the oxidant, the larger the population