Introduction Of Side Groups Research Articles

Passerini polymerization as a novel route for high ionic conductivity solid polymer electrolyte

Polyethylene glycol (PEG) used as solid polymer electrolyte has shown disadvantages of low ionic conductivity and lithium ion transference number due to its high crystallinity. In this study, we propose Passerini three-component polymerization (P-3CP) to modify PEGs for solid polymer electrolytes (SPEs). Thus, a series of PEG-based polyesters (PGPEs) with molar masses between 14,400 and 30,200 gmol−1 are synthesized by P-3CP. The crystallinity of obtained PGPEs is successfully suppressed by the introduction of side groups via P-3CP. SPEs consisting of PGPEs as matrix and bis(trifluoromethane)sulfonimide lithium salt (LiTFSI) with different concentrations were investigated in detail. The SPE composed of PGPE-4000 with 30 wt% LiTFSI presented the best ionic conductivities of 5.85 × 10-5 Scm−1 and 1.94 × 10-3 Scm−1 at room temperature and 80 °C, respectively, which are significantly higher than the commonly used PEG-based SPE. The LiFePO4/Li solid-state lithium-ion battery assembled with PGPE-based SPE showed excellent cycle stability. After 100 cycles at 0.5C at 60 °C, the discharge specific capacity remains 133 mAhg−1. Furthermore, due to the addition of amide side groups, the flame retardant property of PGPE-based SPEs is improved. Compared to PEG, the limiting oxygen index (LOI) values increase from 21.0 to 25.5 after modification by P-3CP. Therefore, the P-3CP is an attractive method to obtain polyesters from dicarboxylic acid or diol monomers for the application in the lithium battery field.

Synthesis of Functionalized Six-Membered-Ring Azahelicenes.

Functionalization, namely the introduction of side groups onto the molecular scaffold of a helicene, may have either the purpose of modifying the electronic properties of the parent helicene, e.g., by adding electron-withdrawing or electron-donating groups, or the scope of providing the helicene with a “handle”, which can be reacted to bind the molecule to another molecule or to a solid structure, such as a carbon or metal surface, or again to allow for complexation of the helicene with metal ions. The possible approaches are two-fold: the synthesis of the helicene can be performed using starting materials that already contain a side group, or the side group can be introduced after the synthesis of the parent helicene. As azahelicenes are helicenes bearing one or more nitrogen atom(s) in the molecular framework, parent azahelicenes can be functionalized on carbon atoms by exploiting the presence of the electron-withdrawing nitrogen atom. Moreover, they can be transformed into quaternary salts, whose properties are quite different from those of the parent azahelicenes in terms of the solubility and electronic properties. This review aims to provide a survey of the different synthetic methods available to attain this fascinating class of compounds.

Anchoring Groups Determine Conductance, Thermopower and Thermoelectric Figure of Merit of an Organic Molecular Junction

Transport properties of molecular junctions are prone to chemical or conformational modifications. Perturbation of the molecule-electrode coupling with anchoring groups or functionalization of the molecule with side groups is a well-characterized method to modulate the thermoelectric properties of molecular junctions. In this study, we used wide-band approximation combined with the non-equilibrium Green’s function (NEGF) formalism to inspect conductance, thermopower and figure of merit of an anthracene molecule coupled to gold (Au) electrodes. To provide a comparative study, three different anchoring groups were used, i.e., thiol, isocyanide and cyanide. The molecule was then perturbed with the amine side group in two positions to explore the interplay between anchoring groups and the side group. We showed that the introduction of side group alters transmission probability near the Fermi energy where transmission peaks are shifted relative to the Fermi level compared to the unperturbed molecule (i.e., without side group), ultimately leading to modified electrical and thermoelectric properties. The greatest value of electrical conductance was achieved when the side-group-perturbed molecule was anchored with isocyanide, whereas the thiol-terminated molecule perturbed with the side group yielded the greatest value of thermal conductance. We found that the Wiedemann-Franz law is violated in the Au-anthracene-Au device. Furthermore, the highest thermopower and figure of merit were attained in the cyanide-terminated perturbed molecule. Our results indicate that charge donating/accepting character of the anchoring group and its interplay with the side group position can modify temperature dependency of conductance, thermopower and figure of merit which is in agreement with experimental findings in organic molecular junctions. Such modifications may potentially contribute to the understanding of emerging conductance-based memory devices designed to mimic the behavior of brain-like synapses.

Estrogenic activity research of a novel fluorinated bisphenol and preparation of an epoxy resin as alternative to bisphenol A epoxy resin

A low estrogenic activity bisphenol 3,5-bis(trifluoromethyl)phenylhydroquinone (BTFMHQ) and its corresponding epoxy resin (BTFMEP) were synthesized via a multi-step procedure including the Meerwein arylation reaction, and followed by nucleophilic reaction. The chemical structures of two monomers were confirmed by their 1H NMR spectra. After curing, the properties of this fluorinated epoxy resin were measured and compared with the commercial epoxy resin diglycidyl ether of bisphenol A (DGEBA). As the result, BTFMEP exhibited good dimensional stability, excellent hydrophobic and low dielectric properties. Furthermore, BTFMEP showed a high glass transition temperature of 142 °C and a lower coefficient thermal expansion (CTE = 55.03 ppm/°C) than that of DGEBA (CTE = 60.71 ppm/°C). Moreover, BTFMEP exhibited the contact angle of 99.6°, which satisfied the standard of hydrophobic material. In addition, BTFMEP showed lower dielectric properties than DGEBA, because the introduction of side groups with high fluorine content into the material improved the electronegativity of epoxy material and reduced the polarizability of molecules efficiently. Herein, we believe the novel epoxy resin (BTFMEP) has a wide application prospect as the alternative to DGEBA.

The stability of ZnO particles in bacterial cellulose and its potential application as wound dressing

Event Abstract Back to Event The stability of ZnO particles in bacterial cellulose and its potential application as wound dressing Hai Lin1, Jiaping Zhang2, Yujiang Fan1 and Xingdong Zhang1 1 Sichuan University, National Engineering Research for Biomaterials, China 2 Southwest Hospital, Third Military Medical University, Institute of Burns, China Introduction: Bacterial cellulose (BC) films can be applied as wound dressing[1]. Loaded with metal or metal oxide particles, the BC films will be improved with anti-microbial property. However, to avoid the possible toxic and side-effect, the stability of loaded particles should be considered together with the updated performance. We investigated the stability of ZnO particles in BC network with or without modification by computer simulation and experimental study. The ZnO containing modified BC films were further characterized as wound dressing. Materials and Methods: The models of ZnO and BC with or without introduced side groups were established by Materials Studio. The interaction between ZnO and BC or modified BC were simulated to meet the convergence criteria. Accordingly, the adsorption energy (EAds) of the process and the interaction energy at steady state (EInt) could be calculated. Based on the computer simulation, BC was modified by maleic anhydride to prepare BC-MA. BC-MA was soaked in zinc acetate ethanol solution and then reacted with sodium hydroxide which was dissolved in ethanol. Following the adequately washing by deionized water, the outcome was lyophilized and further dried in oven to attain ZnO containing BC (BC-MA/ZnO). The stability of ZnO was evaluated by sterilizing BC-MA/ZnO and extracting in PBS, with further detection of ZnO content. The antimicrobial property of BC-MA/ZnO was assessed by oscillation method with Staphylococcus aureus (S.au) and Escherichia coli (E.coli). Results and Discussion: The results of computer simulation between ZnO and BC or BC-MA are shown as Fig.1. The result indicated that EAds and EInt between ZnO and BC-MA are 7.0 and 5.5 times higher than that between ZnO and BC. During the experimental study, the ATR FT-IR spectra prove the successful modification of BC-MA and SEM pictures show the morphology of BC-MA and presence of ZnO particles in BC-MA/ZnO, shown as Fig.2. The thermal gravimetric and atomic absorption spectroscopy analysis indicate the ZnO contents range from 3.48%-14.48%. The results of stability tests confirm the higher stability of ZnO in BC-MA network than that in BC, which is consistent with the theory calculation. The MTT assay indicates that BC-MA/ZnO exhibits no cytotoxicity. The antimicrobial tests demonstrate the BC-MA/ZnO has antimicrobial percent higher than 90% to S.au and 40% to E.coli, respectively. Fig. 3 shows the comparison results. Conclusions: The stability of ZnO particles in bacterial cellulose is enhanced by the introduction of side groups on the glucan molecule. Also, the BC-MA/ZnO films show satisfactory antimicrobial property with no cytotoxicity. Therefore, the improved BC-MA/ZnO films have potential application value as wound dressing. National Natural Science Foundation for Young Scientists of China (51403134); Application Technology Research and Demonstration Projects of Hainan Province China (SQ2014ZDXM0294)

Local chain mobility dependence on molecular structure in polyimides with bulky side groups: Correlation with gas separation properties

The effect of bulky side groups on the molecular mobility and chain packing of three polyimides derived from dianhydrides with m-terphenyl moieties and 2,4,6-trimethyl-m-phenylenediamine has been studied. Moreover, structure–properties relationships in terms of gas transport have been established. One of the polyimides has no side groups, while the other two have a t-butyl group in 5′ (meta) position on the central ring of the m-terphenyl moiety and one of them has also a pivaloylimino group placed in the 2′ (ortho) position. The changes in chain packing of the membranes were evidenced by wide angle X-ray diffraction (WAXS), whilst the molecular mobility was evaluated from the dielectric sub-ambient secondary relaxation, γ relaxation. The WAXS pattern of the polyimide containing both t-butyl and pivaloylimino side groups evidenced a greater degree of packing regularity than in the other two polyimides. Moreover, the additional pivaloylimino group strongly restricted the local molecular mobility associated with the phenylene-imide ring flips. On the other hand, the gas permeability of the polyimides strongly increased with the introduction of side groups. This increase was mainly related to the increase in the gas diffusivity, which could not be explained by an increase in fractional free volume (FFV). The results presented in this work indicate that the difference in gas diffusivity of the substituted polyimides is consistent with a difference in size distribution of free volume elements.

Functionalized Supramolecular Nanoporous Arrays for Surface Templating

Controlled self-assembly and chemical tailoring of bimolecular networks on surfaces is demonstrated using structural derivatives of 3,4:9,10-perylenetetracarboxylic diimide (PTCDI) combined with melamine (1,3,5-triazine-2,4,6-triamine). Two functionalised PTCDI derivatives have been synthesised, Br(2)-PTCDI and di(propylthio)-PTCDI, through attachment of chemical side groups to the perylene core. Self-assembled structures formed by these molecules on a Ag-Si(111)sqrt3 x sqrt3R30 degrees surface were studied with a room-temperature scanning tunneling microscope under ultrahigh vacuum conditions. It is shown that the introduction of side groups can have a significant effect upon both the structures formed, notably in the case of di(propylthio)-PTCDI which forms a previously unreported unimolecular hexagonal arrangement, and their entrapment behaviour. These results demonstrate a new route of functionalisation for network pores, opening up the possibility of designing nanostructured surface structures with chemical selectivity and applications in nanostructure templating.

Coefficients of molecular packing and intrinsic birefringence of aromatic polyimides estimated using refractive indices and molecular polarizabilities

AbstractMolecular structure dependences of the coefficients of molecular packing (Kp) and the intrinsic birefringence (Δn0) were investigated for aromatic polyimides (PIs) using a method based on the modified Lorentz–Lorenz equation and the Vuks equation. This method needs only average refractive indices and polarizability tensors ( ) for PI repeating units. αˆ was calculated using the density functional theory at the B3LYP/6‐31+G(d) theory level that was confirmed as optimal for PI repeating units. Because bent or kinked structures in main chain hinder the ordering of polymer chains, Kp decreases in cases that ether linkages are introduced in the main chain and that kinked‐structured dianhydrides are used. Introduction of side groups, trifluoromethyl (CF3) groups in particular, also causes decreases in Kp. On the other hand, the estimated values of Δn0 are proportional to the calculated anisotropy in αˆ (Δα/Vvdw), thus Δn0 can be well predicted by computation. The values of Δα/Vvdw are decreased not only by bent structures in the main chain (e.g., ether linkage), presence of side groups, but also by large fractions of imide rings in the polymer structures. The estimated values of Δn0 range from 0.338 to 0.470, which are much larger than the reported ones for optically transparent conventional polymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2354–2366, 2004

Preparation and Photoluminescence Characteristics of Carbazole-Poly(p-phenylenevinylene)s

Organic conjugated polymers for light-emitting diodes (LEDs) attract much attention for good optical applications. Organic conjugated polymers have been synthesized for development of photoluminescence (PL) properties.1–3 Since the discovery of poly(pphenylenevinylene) (PPV) exhibiting photoluminescence a variation of conventional PPV was investigated in which backbone conjugation is partially modified using spacers. In 1993, Karasz et al. demonstrated the block copolymer, which has specified units of PPV copolymer with alkyl spacer.4 As mentioned in a lots of papers, progress for achievement of blue-emitting organic polymers has been concentrated on the introduction of side group or newly designed backbones by insertion of heterocycles. We recently synthesized PPV copolymers that have shorter backbone conjugations and examined their luminescence.5, 6 They showed emission spectra in far-blue region and exhibited specific luminescence effect by conjugation length of main chain and methoxy substituents on the phenyl ring. Although hundreds of studies have been conducted using conventional phenylenevinylene-phenylen-vinylene-phenylene unit, effective works need variation of backbones to find a blueemitting polymer showing low turn-on voltage simultaneously. Recently PPV derivatives containing a carbazole moiety in the backbone or side chain have been reported.7–9 In particular, these carbazole-containing PPV copolymers are good materials for making optical and electronic devices due to high hole-transporting capability of carbazole unit.10–12 The introduction of new organic polymers based on the carbazole molecule and exploration of applications in the fabrication of organic light-emitting devices will further interest on carbazole-PPVs for possible optoelectronic applications. So we synthesized three carbazol-PPV derivatives that contain a carbazole unit as a part of main chain and examined luminescence properties. We herein report photoluminescence characteristics and alkoxy substituent effects of carbazole-containing PPV copolymers.

芳香族ポリケトンの合成に関する最近の展開

Aromatic polyketone is one of the most highly performed super engineering plastics With the progress of clarification of the exact feature of structure and thermal behavior of the polymers, a lot of novel aromatic polyketones have appeared and various synthetic approaches were undertaken in these years The recent advances of polyketones are reviewed from synthetic interests. (1) New synthetic reactions, introduction and removal of tentative auxiliary groups in order to maintain the flexibility of polymer chain during chain elongation reaction, and uses of transition metals as a highly effective catalyst were developed for achievement of high-molecular-weight polymer skeleton. (2) Fundamental structural perturbation was undertaken by introduction of crankshaft rings and additional conjugated moieties. (3) Introduction of side groups and their chemical transformation were undertaken to perform new structures and advanced properties. (4) Fine syntheses and reactions of designed oligomers and polymer precursors both for model studies and reactive oligo/polyketones were also investigated. The reports in 1992 and later were mainly surveyed.

Stretching of dissolved chain molecules by the introduction of side groups

Journal of Polymer ScienceVolume 4, Issue 6 p. 759-761 Letter to the Editor Stretching of dissolved chain molecules by the introduction of side groups H. Deuel, H. Deuel Agrikulturchemisches Institut, Eidg. Technische Hochschule, ZürichSearch for more papers by this authorH. Neukom, H. Neukom Agrikulturchemisches Institut, Eidg. Technische Hochschule, ZürichSearch for more papers by this author H. Deuel, H. Deuel Agrikulturchemisches Institut, Eidg. Technische Hochschule, ZürichSearch for more papers by this authorH. Neukom, H. Neukom Agrikulturchemisches Institut, Eidg. Technische Hochschule, ZürichSearch for more papers by this author First published: December 1949 https://doi.org/10.1002/pol.1949.120040612Citations: 5AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume4, Issue6December 1949Pages 759-761 RelatedInformation