Organic Polymer Chains Research Articles

Recent Advances of Organic-Inorganic Hybrid Fluorescent Hyperbranched Polymer: Synthesis, Performance Regulation Strategies and Applications.

The organic-inorganic hybrid fluorescent hyperbranched polymer, including hyperbranched polysiloxane and hyperbranched polyborate, have attracted much attention due to their excellent optical properties and wide range of applications. Hyperbranched polysiloxane and polyborates, prepared by introducing Si or B elements into organic polymer chains at the molecular level through rational molecular design and novel synthesis methods, exhibit outstanding photophysical properties as an indispensable branch of organic-inorganic hybrid fluorescent materials. Herein, this review highlights the recent research progress on hyperbranched polysiloxanes and hyperbranched polyborates, including strategies for regulating their emission wavelengths, quantum yields, and fluorescence lifetimes, potential emission mechanisms, and various applications. Finally, some challenges and promising future directions in the field of organic-inorganic hybrid fluorescent polymers are summarized.

Charge transfer complex induced confinement effect between organic semiconductor and polymer chains for enhancing high-temperature capacitive energy storage

High-temperature polymer dielectrics, renowned for their ultrahigh power densities, robust voltage endurance, and remarkable reliability, present significant potential in optimizing the functionality of microelectronics and electrical power systems. Herein, to elucidate a notable correlation between the confinement effect induced by charge transfer complexes (CTCs) and the discharged energy density (Ue), a series of PI-based composites were synthesized, integrating organic semiconductors with diverse electron affinities. The density functional theory (DFT) simulations revealed that escaping from the CTCs required higher activation energy, besides, a more pronounced electron localization function was observed in the interfacial region between PI chain and F6TCNNQ in comparison to pristine PI, PI/F2TCNQ, and PI/F4TCNQ. Consequently, the CTCs present in PI/F6TCNNQ exhibit the greatest electron localization, significantly impeding electron transport within the composite. Furthermore, at 200 °C, the Ue for the PI/F6TCNNQ composite remains notably high at 5.06 J cm−3 with an efficiency above 90 %, representing a 2.45-fold increase compared to that of pristine PI (2.03 J cm−3). The findings provide evidence for a positive correlation between the confinement effect induced by CTCs and the discharged energy density (Ue) of the composite materials at elevated temperatures, thus offering valuable insights for future investigations focused on all-organic dielectric composite materials.

Recent Progress of Functional Solvent-free Nanofluids: A Review.

Nanoparticles have aroused widespread interest because of their unique surface structure and nano effect, which presents novel characteristics like as sound, light, electricity, magnetism, and thermal properties. However, two critical defects have hindered their applications: (1) poor processability resulting from the high melting temperature (e.g., >1000 °C) for some inorganic nanoparticles; (2) the restriction of the nano effect caused by the easy aggregation of the nanoparticles. To solve those issues, solvent-free nanofluids (SNFs) with hard cores and flexible organic chains were successfully designed and fabricated at the beginning of the twenty-first century. The promising technology of SNFs not only solved the dispersion problem of nanomaterials but also imparted novel functionalization to nanoparticles. Up to now, many researchers have been devoted to developing diverse cores and flexible organic polymer chains to endow SNFs with particular functions, such as conductivity, fluorescence, lubricity, and so on. However, there are few review reports on the research progress in the fabrication and applications of functional SNFs. To gain a better understanding of SNFs, this paper presents an overall investigation into the development, fabrication, as well as the applications of functional SNFs.

3D interconnected polymer/mesoporous silica nanoparticle hybrid materials with hierarchical macro/meso-structures for heavy metal adsorption

This work offers nanohybrid structures for heavy metal ion adsorption from water, which include a unique 3D cross-linked structure that combines organic polymer chains with mesoporous materials to improve adsorption efficiency.

Monodispersed Sub-1nm Inorganic Cluster Chains in Polymers for Solid Electrolytes with Enhanced Li-Ion Transport.

The organic-inorganic interfaces can enhance Li+ transport in composite solid-state electrolytes (CSEs) due to the strong interface interactions. However, Li+ non-conductive areas in CSEs with inert fillers will hinder the construction of efficient Li+ transport channels. Herein, CSEs with fully active Li+ conductive networks are proposed to improve Li+ transport by composing sub-1nm inorganic cluster chains and organic polymer chains. The inorganic cluster chains are monodispersed in polymer matrix by a brief mixed-solvent strategy, their sub-1nm diameter and ultrafine dispersion state eliminate Li+ non-conductive areas in the interior of inert fillers and filler-agglomeration, respectively, providing rich surface areas for interface interactions. Therefore, the 3D networks connected by the monodispersed cluster chains finally construct homogeneous, large-scale, continuous Li+ fast transport channels. Furthermore, a conjecture about 1D oriented distribution of organic polymer chains along the inorganic cluster chains is proposed to optimize Li+ pathways. Consequently, the as-obtained CSEs possess high ionic conductivity at room temperature (0.52mScm-1 ), high Li+ transference number (0.62), and more mobile Li+ (50.7%). The assembled LiFePO4 /Li cell delivers excellent stability of 1000 cycles at 0.5C and 700 cycles at 1C. This research provides a new strategy for enhancing Li+ transport by efficient interfaces.

Flashing ratchet effect for driving carriers to accelerate directional migration in organic photovoltaic devices

The organic electron flashing ratchet experiment describes the phenomenon in which an electric current can be detected, even in the absence of a net potential bias. To understand the experimental mechanism at the quantum level, we utilize the quantum nonadiabatic method to simulate the electron dynamics in an organic polymer chain with the flashing ratchet potential. It is found that electrons exhibit directional migration with a velocity, which depends on both the asymmetry and the flashing frequency of the ratchet potential. In addition, the flashing ratchet, which describes the non-uniform and time-varying electric field, increases the velocity by 58.6% compared to the uniform electric field. The flashing ratchet effect exists intrinsically in actual organic photovoltaics (OPVs), due to the naturally uneven and time-varying inherent electric field caused by various inevitable factors in bulk heterojunctions (BHJ). Moreover, the ratchet potential can be artificially constructed by designing the morphology of the BHJ, which opens a promising avenue for driving electrons to accelerate directional migration, and improving the photoelectric conversion efficiency of OPVs.

A deep learning framework to emulate density functional theory

Density functional theory (DFT) has been a critical component of computational materials research and discovery for decades. However, the computational cost of solving the central Kohn–Sham equation remains a major obstacle for dynamical studies of complex phenomena at-scale. Here, we propose an end-to-end machine learning (ML) model that emulates the essence of DFT by mapping the atomic structure of the system to its electronic charge density, followed by the prediction of other properties such as density of states, potential energy, atomic forces, and stress tensor, by using the atomic structure and charge density as input. Our deep learning model successfully bypasses the explicit solution of the Kohn-Sham equation with orders of magnitude speedup (linear scaling with system size with a small prefactor), while maintaining chemical accuracy. We demonstrate the capability of this ML-DFT concept for an extensive database of organic molecules, polymer chains, and polymer crystals.

Covalent organic framework cathodes for rechargeable Mg batteries

Rechargeable magnesium batteries (RMBs) attract interests as advantageous energy-storage devices, but the application is being hampered by the deficiency of suitable cathodes. Covalent organic frameworks (COFs) are promising selections because of the flexible organic polymer chains and open matrix. Herein, a new family of COF-based polyimide cathodes is synthesized and investigated as RMB cathodes. The COF cathode exhibits a high Mg-storage capacity of 120 mAh g−1, as well as high rate capability and good cycleability, suggesting COFs would be a promising family of cathode materials for RMBs.

Design and assembly of chain-oriented-crystalline multilayered composite with largely improved mechanical strength

Design and assembly of organic/inorganic multilayered composite consisting of alternatively stacking of stiff inorganic platelets and soft organic polymers have great potential for developing next-generation lightweight high-strength materials. Beyond previous designs about the improvement of inorganic nanoplatelet alignment and inter-platelet bonding, a new design concept of control over the physical aggregation state of organic polymer chains within the multilayered structure for mechanical reinforcement is proposed. Based on a typical assembly system of nanoclay platelets and poly (vinyl alcohol) (PVA), a facile three-step process of gelation, uniaxial pre-stretching and evaporation is developed to construct chain-oriented-crystalline multilayered composite, in which the aggregation state of PVA including chain orientation (from 0.020 to 0.897), crystallinity (from 42.8 to 45.9%) and crystallite orientation (from 0.007 to 0.937%) is regulated successfully. These structural changes bring a 4.1-fold increase in the tensile strength of the multilayered composite because of substantial improvement in the strength of PVA layer that enlarges stress transfer from PVA to nanoclay platelets and leads to a failure mode change from the pull-out of nanoclay1 platelets to their fracture. These findings open an avenue for fabricating lightweight high-strength nanocomposites based on inorganic nanoplatelets and crystalline polymers.

Study on the mechanism of improving the lap-shear properties of EVA hot melt adhesives by optical preform waste powders

A large amount of waste is produced during the preparation of optical fiber preforms, and thus the resource utilization of the optical preform waste powders is of great significance. The addition of the calcined optical preform waste powders to pure EVA hot melt adhesives can increase the lap-shear strength. To investigate the reasons for improving the mechanical properties of the pure EVA hot melt adhesives by the optical preform waste powders, XPS, ATR-IR, and Gaussian calculations were utilized to explore the mechanisms of the reactions between the optical preform waste powders and the pure EVA hot melt adhesives. It was found that the hydroxyl groups on the surface of the silicon particles reacted with the ester groups in the EVA resin through the nucleophilic addition and decomposition reactions, which resulted in the formation of long-chain alkyl alcohols and the formation of acylate on the surface of silicon particles, which reduced the agglomeration of the particles. DSC was used to characterize the crystallization behavior of the EVA composite hot melt adhesives with different contents of the optical preform waste powders. With the increase in powder content, the crystallinity of the composite hot melt adhesives decreased obviously, and the decrease in crystallinity increased the lap-shear strength of the composites. Nevertheless, when the crystallinity was too low, a high powder content tended to increase the agglomeration of the particles, which reduced the dispersion compatibility of nanoparticles and organic polymer chains, resulting in a decrease in lap-shear strength.

Robust superhydrophobic coating with hollow SiO2/PAA-b-PS Janus microspheres for self-cleaning and oil–water separation

Superhydrophobic coating can be widely used in many fields because it is not easily wetted by water like lotus leaves. However, most of superhydrophobic coating is difficult to withstand abrasion attack. Herein, hollow SiO2/PAA-b-PS Janus microspheres were synthesized via emulsion interfacial synthesis method using amphiphilic block copolymer of polyacrylic acid block polystyrene (PAA-b-PS) and hollow NH2-SiO2 microspheres as raw materials in this paper. Because the hemisphere grafting organic polymer chain was hydrophobic and the other hemisphere was hydrophilic and contained amino groups, hollow SiO2/PAA-b-PS Janus microspheres exhibited amphiphilic and asymmetrical nature, which was a typical inorganic/polymer Janus microspheres. Robust superhydrophobic coating was facilely achieved using hollow SiO2/PAA-b-PS Janus microspheres on polyurethane pretreated substrate like leather and fabric. Robust superhydrophobic coating after 90 sandpaper abrasion cycles still retained excellent superhydrophobicity. As expected, robust superhydrophobic coating had prominent self-cleaning property against different pollutants and was capable to separate a variety of oil–water mixtures with ultrahigh separation efficiency. The separation efficiency of robust superhydrophobic coating for oil–water mixture was maintained above 98% even after 40 separation cycles. In total, robust superhydrophobic coating constructed by hollow SiO2/PAA-b-PS Janus microspheres possesses distinguished superhydrophobicity, abrasion resistance, self-cleaning, oil–water separation capacity and universality, which shows a promising application in multifunctional coating.

Assembly mechanism of surface-functionalized nanocubes.

Faceted nanoparticles can be used as building blocks to assemble nanomaterials with exceptional optical and catalytic properties. Recent studies have shown that surface functionalization of such nanoparticles with organic molecules, polymer chains, or DNA can be used to control the separation distance and orientation of particles within their assemblies. In this study, we computationally investigate the mechanism of assembly of nanocubes grafted with short-chain molecules. Our approach involves computing the interaction free energy landscape of a pair of such nanocubes via Monte Carlo simulations and using the Dijkstra algorithm to determine the minimum free energy pathway connecting key states in the landscape. We find that the assembly pathway of nanocubes is very rugged involving multiple energy barriers and metastable states. Analysis of nanocube configurations along the pathway reveals that the assembly mechanism is dominated by sliding motion of nanocubes relative to each other punctuated by their local dissociation at grafting points involving lineal separation and rolling motions. The height of energy barriers between metastable states depends on factors such as the interaction strength and surface roughness of the nanocubes and the steric repulsion from the grafts. These results imply that the observed assembly configuration of nanocubes depends not only on their globally stable minimum free energy state but also on the assembly pathway leading to this state. The free energy landscapes and assembly pathways presented in this study along with the proposed guidelines for engineering such pathways should be useful to researchers aiming to achieve uniform nanostructures from self-assembly of faceted nanoparticles.

Modification of the optical properties of molecular chains upon coupling to adatoms

Adsorbed atoms (adatoms) coupled to the matrix of solid state host materials as impurities can significantly modify their properties. Especially in low-dimensional materials, such as one-dimensional organic polymer chains or quasi-one-dimensional graphene nanoribbons, intriguing manipulation of the optical properties, such as the absorption cross section, is possible. The most widely used approach to couple quantum emitters to optical antennas is based on the Purcell effect. This formalism, however, does not comprise charge transfer from the emitter to the antenna, but only spontaneous emission of the quantum emitter into the tailored photonic environment, that is evoked by the antenna. To capture such effects, we present a tight-binding formalism to couple an adatom to a finite Su-Schrieffer-Heeger chain, where the former is treated as a two-level system and the latter acts as an optical antenna. We systematically analyze how the coupling strength and the position of the adatom influence the optical properties of the molecular chains in the model. We take into account charge transfer from the adatom to the antenna and vice versa via an inter-system hopping parameter, and also include Coulomb interaction within the antenna as well as between the adatom and the antenna. We show that coupling the adatom to one of the bulk atoms of the linear chain results in a substantial change in optical properties already for comparatively small coupling strengths. We also find that the position of the adatom crucially determines if and how the optical properties of the chains are altered. Therefore, we identify this adatom-chain hybrid system as a tunable platform for light-matter interaction at the nanoscale.

Antibacterial Activity of Photocatalytic Metal Oxide Thin Films Deposited by Layer-by-Layer Self-Assembly.

This paper reports the use of the Layer-by-Layer self-assembly (LbL) as an efficient technique for the fabrication of thin-films with antibacterial activity. The LbL coatings are composed of a positive polyelectrolyte such as Poly(allylamine hydrochloride) (PAH) and an anionic polyelectrolyte such as Poly(sodium 4-styrene sulfonate) solution (PSS). In addition, these polyelectrolytes can be also used as an adequate encapsulating agent of specific metal oxide precursors such as titanium dioxide (TiO₂) and iron oxide (Fe₂O₃) nanoparticles, making possible the fabrication of hybrid thin films composed of organic polymeric chains related to the polyelectrolytes and inorganic structure associated to the metal oxide nanoparticles. Four different LbL coatings have been fabricated and a comparative study about the resultant topographical, optical and wettability properties is presented by using light interferometry, atomic force microscopy (AFM), UV-Vis spectroscopy and water contact angle (WCA) measurements. In addition, X-ray fluorescence (XRF) has been also employed in order to corroborate the presence of metal oxide precursors inside the polymeric chains of the polyelectrolytes. Finally, the antibacterial tests have demonstrated that LbL coatings composed of metal oxide nanoparticles produce an enhancement in the efficacy and antibacterial activity.

Self-assembly of a layered two-dimensional molecularly woven fabric.

Fabrics-materials consisting of layers of woven fibres-are some of the most important materials in everyday life1. Previous nanoscale weaves2-16 include isotropic crystalline covalent organic frameworks12-14 that feature rigid helical strands interlaced in all three dimensions, rather than the two-dimensional17,18 layers of flexible woven strands that give conventional textiles their characteristic flexibility, thinness, anisotropic strength and porosity. A supramolecular two-dimensional kagome weave15 and a single-layer, surface-supported, interwoven two-dimensional polymer16 have also been reported. The direct, bottom-up assembly of molecular building blocks into linear organic polymer chains woven in two dimensions has been proposed on a number of occasions19-23, but has not previously been achieved. Here we demonstrate that by using an anion and metal ion template, woven molecular 'tiles' can be tessellated into a material consisting of alternating aliphatic and aromatic segmented polymer strands, interwoven within discrete layers. Connections between slowly precipitating pre-woven grids, followed by the removal of the ion template, result in a wholly organic molecular material that forms as stacks and clusters of thin sheets-each sheet up to hundreds of micrometres long and wide but only about four nanometres thick-in which warp and weft single-chain polymer strands remain associated through periodic mechanical entanglements within each sheet. Atomic force microscopy and scanning electron microscopy show clusters and, occasionally, isolated individual sheets that, following demetallation, have slid apart from others with which they were stacked during the tessellation and polymerization process. The layered two-dimensional molecularly woven material has long-range order, is birefringent, is twice as stiff as the constituent linear polymer, and delaminates and tears along well-defined lines in the manner of a macroscopic textile. When incorporated into a polymer-supported membrane, it acts as a net, slowing the passage of large ions while letting smaller ions through.

Fabrication and characterization of sulfonated polybenzimidazole/sulfonated imidized graphene oxide hybrid membranes for high temperature proton exchange membrane fuel cells

ABSTRACTThe sulfonated polybenzimidazole (sPBI)/sulfonated imidized graphene oxide (SIGO) was evaluated to be a potential candidate for high temperature proton exchange membranes fuel cells (HT‐PEMFCs). Multifunctionalized covalently bonded SIGO is incorporated in sPBI matrix to resolve the drawbacks such as low proton conductivity, poor water uptake, and ion‐exchange capacity (IEC) of sPBI polymer, synthesized by direct polycondensation in phosphoric acid for the application of proton exchange membranes. Strong hydrogen bonding among multifunctional groups established a neighborhood of interconnected hydrophobic graphene sheets and organic polymer chains. It provides hydrophobic–hydrophilic phase separation and facile proton hopping architecture. The optimized sPBI/SIGO (15 wt %) revealed 2.45 meq g−1 IEC; 5.81 mS cm−1 proton conductivity [120 °C and 10% relative humidity (RH)] and 2.45% bound water content. The maximum power density of the sPBI/SIGO‐15 membrane was 0.40 W cm−2 at 160 °C (5% RH) and ambient pressure with stoichiometric feed of H2/air. This recommends that sPBI/SIGO composite membranes are compatible candidate for HT‐PEMFCs. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47892.

Microstructure and Formula Optimization of Co2 Flooding Composite Gel in Supercritical Carbon Dioxide

Injection of CO2 into low permeability reservoirs tend to both enhance the oil recovery effectively and reduce the CO2 emissions. However, the reservoir heterogeneity, reservoir cracks and viscous fingering lead to CO2 channeling occuring during the process of CO2 flooding. Four parameters (CO2 pressure, simulation temperature, reaction time, and concentrations of reactants) were optimized through L16(44) orthogonal experiment, and the most appropriate conditions for inorganic gel were also acquired simultaneously as follows: reaction pressure 9.0 MPa, reaction temperature 32.01, reaction time 14.0 h, and sodium silicate mass concentration 4.0%. The compound gel was synthesized by the method of blending sodium silicate solution with an acrylamide system in supercritical CO2. The microstructure of the compound gel was researched through environmental scanning electron microscopy (ESEM), and the results showed that, in supercritical CO2, the inorganic gel particle equaly dispersed in the organic gel network inside the structure, thus the support framework of the organic polymer chain was formed and the strength of the compound gel was finally enhanced.

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

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...

Self-assembly of regioregular poly [2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene], pBTTT-C14 in solvent-mixture and study of its junction behaviour

The molecular ordering in organic polymer chains through π-π interactions is emerged to improve semiconductor performance. In the present work, long-range ordering of poly [2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene], pBTTT-C14 fiber is optimized in mixture of good and poor solvent (chloroform+toluene) blend using the concept of solvent driven self-assembly. Here, self-assembly is introduced by ageing followed by complete dissolution at elevated temperature in solvent-mixture. UV–visible spectroscopy demonstrated that the evidence of long range pBTTT-C14 fiber when experimentation is carried out in mixture of chloroform and toluene (9:1 v/v). However, in chloroform only, aggregation is slow while in toluene, aggregation is very fast under similar conditions. The fiber growth and its size are further verified by atomic force microscopy and HRTEM exemplified that the resultant aggregation of polymer chain in nanometric (diameter∼11 nm) range. Thereafter, the change in surface potential of fiber is studied by KPFM. This fibrous polymer is further sandwiched between ITO and Al-metal in order to study its junction behaviour. Fibrous pBTTT-C14 exhibits unsymmetrical charge transport properties over its isolated analogue with ∼9 times enhancement in mobility and ∼6.5 times enhancement in forward current density under the applied potential (−1.0 V to +1.0 V). This is owing to existence of a new charge transition path along the aggregation that consists of trapped charge between π-π stacking.

SiO2-TiO2-PBC nanocomposite film morphology, solvent swelling, estimated χ parameter, and liquid transport

Tetraethylorthosilicate (TEOS), titanium isopropoxide (TIP), and poly [t-butylstyrene -b- ethylene -alt- propylene -b- sulfonated styrene -b- ethylene -alt- propylene -b- t-butylstyrene] or Pentablock Copolymer (PBC) were used to create a series of nanocomposite inorganic-organic materials. Sol-gel chemistry provided a route to maximize the interactions between an inorganic network and organic polymer chains. The inorganic materials presence affected film morphology, swelling behavior, and liquid transport properties. PBC morphology was disrupted by TIP, which is attributed to enhanced interactions between inorganic and organic domains. This caused micro-phase separation that was observed as a morphology change from ordered to random. These dynamic interfacial interactions perturbed the chain's packing efficiency, which caused a decrease in the estimated polymer density within nanocomposites from 1.036 g/mL to 0.879 g/mL. Inorganic concentration within PBC caused a significant increase in alcohol uptake from around 200 wt% to more than 300 wt%, and a decrease in THF uptake from around 400 wt% to 20 wt%. Nanocomposite film swelling was modeled using the Flory-Rehner Equation. Modeling predicted that increasing inorganic content shifted the material to a more polar system. This led to a decrease in χ with alcohols and water, and an increase in χ with THF. Alcohol and fructose transport through an inorganic-organic film increased four times without sacrificing selectivity.