scholarly journals Oxidative Coupling Copolymerization of 2,6-Dimethylphenol and Dihydroxynaphthalene Affording Poly(phenylene oxide) Derivatives

2015 ◽  
Vol 2015 ◽  
pp. 1-6
Author(s):  
Shigeki Habaue ◽  
Ryosuke Ito ◽  
Ken Okumura ◽  
Yuki Takamushi
Keyword(s):  
Functional Groups ◽  
Oxidative Coupling ◽  
Hydroxyl Groups ◽  
Phenylene Oxide ◽  
Cu Catalyst

The oxidative coupling copolymerization between 2,6-dimethylphenol (DMP) and dihydroxynaphthalenes, such as the 2,3- and 2,6-dihydroxynaphthalenes (2,3- and 2,6-DHN), was carried out using a Cu catalyst under an O2 atmosphere. The polymerization was significantly affected by the structure of the comonomer, and the copolymers were efficiently obtained during the copolymerization of DMP and 2,6-DHN. The obtained copolymers containing hydroxyl groups of the DHN unit were further transformed into polymers containing ester and urethane groups. The obtained copolymers containing various functional groups showed a very different solubility from that of the homopolymer of DMP.

scholarly journals Mechanical Properties of Graphene Oxide Coupled by Multi-Physical Field: Grain Boundaries and Functional Groups

Crystals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 62
Author(s):  
Xu Xu ◽  
Zeping Zhang ◽  
Wenjuan Yao
Keyword(s):  
Mechanical Properties ◽  
Graphene Oxide ◽  
Grain Boundaries ◽  
Functional Groups ◽  
Oxygen Content ◽  
Tensile Fracture ◽  
Hydroxyl Groups ◽  
Molecular Configuration ◽  
Spatial Design ◽  
Out Of Plane

Graphene and graphene oxide (GO) usually have grain boundaries (GBs) in the process of synthesis and preparation. Here, we “attach” GBs into GO, a new molecular configuration i.e., polycrystalline graphene oxide (PGO) is proposed. This paper aims to provide an insight into the stability and mechanical properties of PGO by using the molecular dynamics method. For this purpose, the “bottom-up” multi-structure-spatial design performance of PGO and the physical mechanism associated with the spatial structure in mixed dimensions (combination of sp2 and sp3) were studied. Also, the effect of defect coupling (GBs and functional groups) on the mechanical properties was revealed. Our results demonstrate that the existence of the GBs reduces the mechanical properties of PGO and show an “induction” role during the tensile fracture process. The presence of functional groups converts in-plane sp2 carbon atoms into out-of-plane sp3 hybrid carbons, causing uneven stress distribution. Moreover, the mechanical characteristics of PGO are very sensitive to the oxygen content of functional groups, which decrease with the increase of oxygen content. The weakening degree of epoxy groups is slightly greater than that of hydroxyl groups. Finally, we find that the mechanical properties of PGO will fall to the lowest values due to the defect coupling amplification mechanism when the functional groups are distributed at GBs.

Diffusion coefficients and viscosities of organic aerosol components through equilibrium and non-equilibrium molecular dynamics simulations

2021 ◽  
Author(s):  
Katerina S. Karadima ◽  
Vlasis G. Mavrantzas ◽  
Spyros N. Pandis
Keyword(s):  
Molecular Dynamics ◽  
Functional Groups ◽  
Organic Compounds ◽  
Diffusion Coefficients ◽  
Amorphous Solid ◽  
Good Effect ◽  
Hydroxyl Groups ◽  
Chemical Structures ◽  
Organic Particles ◽  
Non Equilibrium

<p>Organic aerosols have been typically considered to be liquid, with equilibration between gas and aerosol phase assumed to be reached within seconds. However, Virtanen et al. (Nature, 2010) suggested that particles in amorphous solid state may also occur in the atmosphere implying that mass transfer between the atmospheric particulate and gas phases may be much slower than initially thought. Experimentally, the direct measurement of the diffusion coefficients of different compounds inside atmospheric organic particles is challenging. Thus, an indirect approach is usually employed, involving viscosity measurements and then estimation of diffusion coefficients via the Stokes-Einstein equation, according to which the diffusion coefficient is inversely proportional to the medium viscosity. However, the corresponding diffusion estimates are highly uncertain, especially for highly viscous aerosols which is the most important case. Molecular simulation methods, such as molecular dynamics (MD), can be an alternative method to determine directly the diffusion rates and the viscosity of the constituents of atmospheric organic particles. MD also provides detailed information of the exact dynamics and motion of the molecules, thus offering a deeper understanding on the underlying mechanisms and interactions.</p><p>In the present work, we use equilibrium and non-equilibrium MD simulations to estimate the viscosity and diffusion coefficients of bulk systems of representative organic compounds with different chemical structures and physicochemical characteristics. Hydrophilic and hydrophobic compounds representative of primary and secondary oxidized organic products and of primary organic compounds emitted by various sources are considered. The viscosity and self-diffusion coefficients calculated by our simulations are in good agreement with available experimentally measured values. Our results confirm that the presence of carboxyl and hydroxyl groups in the molecule increases the viscosity. The number of carboxyl and hydroxyl groups, in particular, seems to have a good effect on diffusivity (the diffusivity decreases as the number of these functional groups increase), and to a lesser extent on the viscosity. We also discuss the role of the hydrogen bonds formed between these functional groups.</p>

Effect of Acid on Surface Hydroxyl Groups on Kaolinite and Montmorillonite

2018 ◽  
Vol 232 (3) ◽  
pp. 409-430 ◽  
Author(s):  
Sarah K. Sihvonen ◽  
Kelly A. Murphy ◽  
Nancy M. Washton ◽  
Muhammad Bilal Altaf ◽  
Karl T. Mueller ◽  
...  
Keyword(s):  
Functional Groups ◽  
Acid Treatment ◽  
Atmospheric Transport ◽  
Magic Angle Spinning ◽  
Resonance Spectroscopy ◽  
Hydroxyl Groups ◽  
Magic Angle ◽  
Surface Hydroxyl ◽  
Surface Hydroxyl Groups ◽  
Angle Spinning

AbstractMineral dust aerosol participates in heterogeneous chemistry in the atmosphere. In particular, the hydroxyl groups on the surface of aluminosilicate clay minerals are important for heterogeneous atmospheric processes. These functional groups may be altered by acidic processing during atmospheric transport. In this study, we exposed kaolinite (KGa-1b) and montmorillonite (STx-1b) to aqueous sulfuric acid and then rinsed the soluble reactants and products off in order to explore changes to functional groups on the mineral surface. To quantify the changes due to acid treatment of edge hydroxyl groups, we use19F magic angle spinning nuclear magnetic resonance spectroscopy and a probe molecule, 3,3,3-trifluoropropyldimethylchlorosilane. We find that the edge hydroxyl groups (OH) increase in both number and density with acid treatment. Chemical reactions in the atmosphere may be impacted by the increase in OH at the mineral edge.

Construction and surface/interface behavior of bio-functional surface layer by microwave-excited Ar/H2O plasma-induced polyethylene glycol polymerization

2017 ◽  
Vol 31 (16-19) ◽  
pp. 1744093
Author(s):  
Z. Shao ◽  
A. Ogino ◽  
M. Nagatsu
Keyword(s):  
Surface Layer ◽  
Functional Groups ◽  
Photoelectron Spectroscopy ◽  
Optical Emission ◽  
Aging Effect ◽  
Hydroxyl Groups ◽  
Functional Surface ◽  
Interface Behavior ◽  
Water Contact ◽  
Spacer Layer

Ar/H2O microwave-excited surface-wave plasma-induced grafting-polymerization and crosslinking technique was presented to construct a bio-functional surface layer. Optical emission spectroscopy was used to diagnose Ar/H[Formula: see text]O plasma. The surface/interface behavior especially the aging effect of hydroxyl groups over the grafted PEG spacer layer was investigated by measuring water contact angle and X-ray photoelectron spectroscopy. The results demonstrate that the addition of water vapor into Ar plasma can optimize the concentration of hydroxyl functional groups on surface; grafted PEG spacer layer can provide a long-term hydrophilicity of PU films, and alleviate the aging effect of hydroxyl functional groups.

A novel amino acid analysis method using derivatization of multiple functional groups followed by liquid chromatography/tandem mass spectrometry

The Analyst ◽  
2015 ◽  
Vol 140 (6) ◽  
pp. 1965-1973 ◽  
Author(s):  
Yohei Sakaguchi ◽  
Tomoya Kinumi ◽  
Taichi Yamazaki ◽  
Akiko Takatsu
Keyword(s):  
Mass Spectrometry ◽  
Amino Acid ◽  
Functional Groups ◽  
Amino Acid Analysis ◽  
Hydroxyl Groups ◽  
Tandem Mass ◽  
Analysis Method ◽  
Chromatography Tandem Mass Spectrometry ◽  
Liquid Chromatography Tandem Mass ◽  
Phenolic Hydroxyl Groups

We have developed a novel amino acid analysis method using derivatization of multiple functional groups (amino, carboxyl, and phenolic hydroxyl groups).

scholarly journals Terminal Groups Dependent Near-Field Enhancement Effect of Ti3C2Tx Nanosheets

2020 ◽  
Author(s):  
Ying-Ying Yang ◽  
Wen-Tao Zhou ◽  
Wei-Long Song ◽  
Qing-Quan Zhu ◽  
Hao-Jiang Xiong ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Oxidation Resistance ◽  
Functional Groups ◽  
Near Field ◽  
Field Enhancement ◽  
Electron Injection ◽  
Enhancement Effect ◽  
Hydroxyl Groups ◽  
Physical And Chemical

Abstract Both multilayered (ML) and few-layered (FL) Ti3C2Tx nanosheets with different dominant terminal groups have been prepared through a typical etching and delaminating procedure. Various characterizations confirm that the physical and chemical performance of the nanosheets are dependent on the dominant functional groups. It has been demonstrated that ML-Ti3C2Tx has been mainly terminated by O-related groups, which result in better oxidation resistance and stronger near-field enhancement effect. As for FL-Ti3C2Tx, which is mainly terminated by hydroxyl groups, it can be better dispersed in aqueous solution and could confine stronger near-field after coupling to Ag nanostructures by electron injection.

scholarly journals Biobased Hyperbranched Poly(ester)s of Precise Structure for the Release of Therapeutics

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Bob Howell ◽  
Tracy Zhang ◽  
Patrick Smith
Keyword(s):  
Sustained Release ◽  
Functional Groups ◽  
Active Agent ◽  
Monomer Conversion ◽  
Single Type ◽  
Hydroxyl Groups ◽  
Naturally Occurring ◽  
Hyperbranched Poly ◽  
The Difference ◽  
Smith Model

Hyperbrached poly(ester)s derived from naturally-occurring biomonomers may serve as excellent platforms for the sustained-release of therapeutics. Those generated from glycerol are particularly attractive. Traditionally, the difference in reactivity of the hydroxyl groups of glycerol has precluded the formation of well-defined polymers at high monomer conversion without gelation. Using the Martin-Smith model to select appropriate monomer ratios (ratios of functional groups), polymerization may be carried out to high conversion while avoiding gelation and with the assurance of a single type of endgroup. Various agents may be attached via esterification, amide formation or other process. Sustained release of the active agent may be readily achieved by enzyme-catalyzed hydrolysis.

Soil Chemistry

2003 ◽  
Author(s):  
Anthony S. R. Juo ◽  
Kathrin Franzluebbers
Keyword(s):  
Surface Charge ◽  
Functional Groups ◽  
Soil Chemistry ◽  
Chemical Properties ◽  
Hydroxyl Groups ◽  
Oh Groups ◽  
Surface Hydroxyl ◽  
Mineral Structure ◽  
Ph Dependent ◽  
Soil Colloids

Soil chemistry deals with the chemical properties and reactions of soils. It is essentially the application of electrochemistry and colloid chemistry to soil systems. Major topics include surface charge properties of soil colloids, cation and anion sorption and exchange, soil acidity, soil alkalinity, soil salinity, and the effects of these chemical properties and processes on soil biological activity, plant growth, and environmental quality. The ability of the electrically charged surface of soil colloids to retain nutrient cations and anions is an important chemical property affecting the fertility status of the soil. There are two major sources of electrical charges on soil organic and inorganic colloids, namely, permanent or constant charges and variable or pH-dependent charges. Permanent or constant charges are the result of the charge imbalance brought about by isomorphous substitution in a mineral structure of one cation by another of similar size but differing valence (see also section 2.3.2). For example, the substitution of Mg2+ for Al3+ that occurs in Al-dominated octahedral sheets of 2:1 clay minerals results in a negative surface charge in smectite, vermiculite, and chlorite. The excess negative charges are then balanced by adsorbed cations to maintain electrical neutrality. Permanent negative charges of all 2:1 silicate minerals arise from isomorphous substitutions. The l:l-type clay mineral, kaolinite, has only a minor amount of permanent charge due to isomorphic substitution. The negative charges on kaolinite originate from surface hydroxyl groups on the edge of the mineral structure and are pH-dependent. Variable or pH-dependent charges occur on the surfaces of Fe and Al oxides, allophanes, and organic soil colloids. This type of surface charge originates from hydroxyl groups and other functional groups by releasing or accepting H+ ions, resulting in either negative or positive charges. Other functional groups are hydroxyl (OH) groups of Fe and/or Al oxides and allophanes and the COOH and OH groups of soil organic matter. Variable-charge soil colloids bear either a positive or a negative net surface charge depending on the pH of the soil. The magnitude of the charge varies with the electrolyte concentration of the soil solution.

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