Poly(phenylene sulfide−tetraaniline): The Soluble Conducting Polyaniline Analogue with Well-Defined Structures

A novel conducting polymer poly(phenylene sulfide−tetraaniline) (PPSTEA), with tetraaniline (TA) and phenylene sulfide (PS) segments in its repeat unit, has been synthesized through an acid-induced polycondensation reaction of 4-methylsulfinylphenyl-capped tetraaniline. The new polymer, which represents the first soluble conducting polyaniline analogue with well-defined structure, has high molecular weight, good solubility in common solvents, and good film-forming properties. Its electrical property is analogous to polyaniline. The conductivity of preliminarily protonic-doping PPSTEA is up to 100 S/cm. This synthetic strategy appears to be general for developing novel well-defined polyaniline analogue containing much longer fixed conjugation length

Adsorption of Cationic Hydroxyethylcellulose Derivatives onto Planar and Curved Gold Surfaces

The adsorption of two positively charged hydroxyethylcellulose derivatives with 7 and 60 mol % positively charged groups and a cationic, hydrophobically modified hydroxyethylcellulose containing 1 mol % hydrophobic groups and 7 mol % charged groups onto flat and spherical citrate-coated gold surfaces of different sizes has been investigated. The planar surfaces were studied by means of the quartz crystal microbalance with dissipation monitoring, whereas nanoparticle suspensions were examined using dynamic light scattering and UV−vis spectroscopy. Two different driving forces for adsorption have been evaluated: the electrostatic interaction between the positive charges on the polymers and the negatively charged gold surfaces and the affinity of the polymers for gold due to hydrophobic interactions. The comparison between the data obtained from curved and planar surfaces suggests a strong correlation between surface curvature and adlayer conformation in the formation of the hybrid polymer−gold nanoparticles. The influence of particle size on the amount of adsorbed polymer has been evaluated for the different polymers. The impact of the ionic strength on polymer adsorption has been explored, and the adsorbed polymer layer has been found to protect the gold nanoparticles from aggregation when salt is added to the solution. The addition of salt to a mixture of gold particles and a charged polymer can induce a thicker adsorbed layer at low salinity, and desorption was found at high levels of salt addition

Synthesis and Characterization of a Thermoresponsive Copolymer with an LCST–UCST-like Behavior and Exhibiting Crystallization

In this work, the diblock copolymer methoxy-poly(ethylene glycol)-block-poly(ε-caprolactone) (MPEG–b-PCL) was synthesized with a block composition that allows this polymer in aqueous media to possess both an upper critical solution temperature (UCST) and a lower critical solution temperature (LCST) over a limited temperature interval. The value of the UCST, associated with crystallization of the PCL-block, depended on heating (H) or cooling (C) of the sample and was found to be CPUCSTH = 32 °C and CPUCSTC = 23 °C, respectively. The LCST was not affected by the heating or cooling scans; assumed a value of 52 °C (CPLCSTH = CPLCSTC). At intermediate temperatures (e.g., 45 °C), dynamic light scattering (DLS), small-angle X-ray scattering (SAXS), and cryogenic transmission electron microscopy (cryo-TEM) showed that the solution consisted of a large population of spherical core–shell particles and some self-assembled rodlike objects. At low temperatures (below 32 °C), differential scanning calorimetry (DSC) and wide-angle X-ray scattering (WAXS) in combination with SAXS disclosed the formation of crystals with a cylindrical core–shell structure. Cryo-TEM supported a thread-like appearance of the self-assembled polymer chains. At temperatures above 52 °C, incipient phase separation took place and large aggregation complexes of amorphous morphology were formed. This work provides insight into the intricate interplay between UCST and LCST and the type of structures formed at these conditions in aqueous solutions of MPEG–b-PCL diblock copolymers

Miktoarm PEG–PCL Star Copolymer (AB6) Blend Composite Solid Electrolyte for All-Solid-State Lithium Metal Battery

A series of AB6 type-7 miktoarm star copolymers consisting of poly­(ethylene glycol) (PEG) as the A arm and poly­(ε-caprolactone) (PCL) as the B arm are synthesized by controlled ring-opening polymerization of the ε-caprolactone monomer. The chemical structure is confirmed and characterized by nuclear magnetic resonance (NMR) and Fourier transform infrared (FT-IR) spectroscopies. The synthesized PEG–PCL star copolymers (PAB6) (Mn = 8400, 16,820, and 32,480) with arms of different lengths are introduced into the poly­(ethylene oxide)-based solid electrolyte system. Moreover, the electrochemical, mechanical, and thermochemical properties of composite solid polymer electrolytes are enhanced by adding three miktoarm PEG–PCL star copolymers (referred to as PAB6–1, PAB6–2, and PAB6–3). The unique low-molecular-weight miktoarm copolymers with a central etheroxy group and branched carboxyl groups interact with poly­(ethylene oxide) segments and lithium ions, enhancing the segment mobility of the polymer and lithium-ion transfer. Therefore, all-solid-state lithium metal batteries by the serial miktoarm star copolymer composite electrolytes display a high capacity retention of 128.1 mAh g–1 after 390 cycles

Charged Star Diblock Copolymers in Dilute Solutions: Synthesis, Structure, and Chain Conformations

We present a systematic investigation of a novel series of star polymers consisting of arms made up from poly­(<i>N</i>-isopropylacrylamide)-<i>b</i>-poly­(2-acrylamido-2-methylpropanesulfonate) (PNIPAAM-<i>block</i>-PAMPS) block copolymers. The polymers were synthesized as a 3-arm and 2-arm (i.e., a tetrablock copolymer) using a “core-first” method and a sequential atomic transfer radical polymerization (ATRP) protocol. Using asymmetric flow field-flow fractionation (AFFFF), Zetasizer, and small-angle X-ray scattering (SAXS), the phase behavior and nanostructure of the system in dilute solutions are studied in detail. While AFFFF equipped with a light scattering and refractive index detectors provides distribution of molecular weight and overall sizes in solution, we use SAXS combined with theoretical modeling to elucidate the inter- and intramolecular interactions of the star polymers. In particular, by employing a detailed model for a star-diblock copolymer assuming Gaussian chain statistics, we extract the chain conformation for <i>each polymer block separately</i>. We find that the radii of gyration, <i>R</i>_g, for both PNIPAAM and PAMPS are very similar to the expected dimension of free chains in solution. By adding salt, we show that the strong interstar repulsion found in water is dramatically reduced after adding as little as 0.025 M NaCl. Further increase of NaCl up to 0.2 M shows that the system essentially behaves as neutral polymers in a good solvent. Concerning the chain conformations, addition of NaCl seems to have a small effect on the <i>R</i>_g of the different blocks