Changes in the standard transformed thermodynamic properties of enzyme-catalyzed reactions with ionic strength

The ionic strength has significant effects on the thermodynamic properties of ionic species and on the transformed thermodynamic properties of biochemical reactants at specified pH values. These effects are discussed for species, reactants, and enzyme-catalyzed reactions. This has led to three new thermodynamic properties: (z(j)(2) - NH(j)), (z(2) - N(H))(i), and Delta(r)(z((2)-N(H)), which are referred to as ionic strength coefficients. The first of these is a property of a species, the second is a property of a reactant, and the third is the property of an enzyme-catalyzed reaction. The effects of ionic strength on standard thermodynamic properties of species, standard transformed thermodynamic properties of reactants, and standard transformed thermodynamic properties of enzyme-catalyzed reactions are proportional to these new thermodynamic properties.     

PURIFIED POLAR POLYFLUORENE FOR LIGHT-EMITTING DIODES AND LIGHT-EMITTING ELECTROCHEMICAL CELLS

Conjugated ployfluorene with 2-(2-(2-methoxyethoxy)ethoxy)ethyl groups(EO-PF)is prepared by the palladiumcatalyzed Suzuki coupling reaction.The polymer is purified carefully by a simple chemical procedure.The inductively coupled plasma(ICP)test shows palladium-catalyst in the polymer can be removed by this procedure.The thermal properties,electrochemical properties,UV-Vis absorption properties,photoluminescence properties and electroluminescent properties of the polymer without(EO-PF1)or with purification(EO-PF2)are studied.EO-PF2 shows better PL CIE coordinates in THF solutions as blue light-emitting materials and better photoluminescence stability in thin solid films. Polymer light emitting diodes and electrochemical cells based on EO-PF2 exhibit somewhat improved optoelectronic performance than control devices of EO-PF1.     

Molecular dynamics simulation of mechanical properties of TATB/fluorine-polymer PBXs along different surfaces

TATB (1,3,5-triamino-2,4,6-trinitrobenzene) is the well-known high insensitive explosive. With TATB as the main body (90% and above) the polymer bonded explosives ( PBXs) contain a small amount of poly-mers (5%―10%). The composite materials with good saf…     

Mechanical properties of epitaxially crystallized 1,4-polybutadiene on uniaxially oriented isotactic polypropylene

The structure and mechanical properties of polypropylene (PP)-trans-1,4-polybutadiene (PBD) blends were investigated. It was found that PBD can epitaxially crystallize on PP. An increase in mechanical properties (Young's modulus, fracture stress) is observed, despite the fact that pure PBD has much worse mechanical properties compared to PP. The epitaxial morphology is responsible for the synergetic effects in the mechanical properties.Dedicated to Prof. Dr. W. Pechhold on the occasion of his 60th birthday     

Studies on thermotropic liquid crystalline polymer. XI. Effect of amide group on thermotropic liquid crystalline polymer properties

A series of poly(azomethine)s containing amide, ether, or ester groups was prepared by the condensation of dialdehydes with various diamines. The thermotropic liquid crystalline properties were examined by DSC and microscopic observations. The effects of the number and position of amide groups, which are attached to the rigid segment, on the thermotropic liquid crystalline properties of the homo-and copoly(amide-azomethine-ether)s were also investigated in this study. The copolymerization took place by changing the amount of amide group to obtain copoly(amide-azomethine) ( P13 and P14 ) which exhibit thermotropic liquid crystalline properties. The poly(azomethine)s containing ether or ester groups also exhibited thermotropic liquid crystalline properties. © 1993 John Wiley & Sons, Inc.     

Correlation between Functionated Structure and Nanomechanical Property Profiles of Silsesquioxane Films and Bulks

Three silsesquioxane (SSO) building blocks based on [3-(methacryloxy)propyl]trimethoxysilane (MPMS), [(3-glycidoxy)propyl] trimethoxysilane (GPMS), (vinyl)trimethoxysilane (VMS) and modified with 15 wt-% tetraethoxysilane (TEOS) were prepared using hydrolytic condensation. The hardness, elastic modulus and harmonic contact stiffness for three films [f-MTSSO (film-MPMS-TEOS-SSO), f-GTSSO and f-VTSSO] and bulks (b-MTSSO, b-GTSSO and b-VTSSO) derived from the three SSOs were tested by instrument-indentation testing. Different profiles of nanomechanical properties of the films can be attributed to a different functionality and the functionated structure of the different SSOs. The f-MTSSO shows better mechanical properties which are higher than the other two films containing more OH or OCH₃ groups. For the f-GTSSO with a bulky organic substituent, the unsatisfactory properties resulting from ring opening during hydrolytic condensation and an incomplete crosslinking network are discussed. However, the nanomechanical properties of the three bulks are very different from the corresponding nanomechanical properties of their films: b-VTSSO possesses the best nanomechanical properties (note: not b-MTSSO) among three bulks due to the differences in reaction conditions and chain less flexibility which are also discussed.     

Reactively compatibilized and dynamically vulcanized thermoplastic elastomers based on high-density polyethylene and reclaimed rubber

Melt blending was employed to prepare thermoplastic elastomer (TPE) of reclaimed rubber (RR) and high density polyethylene (HDPE). Mechanical properties of TPE samples were improved in different methods including dynamic vulcanization and reactive blending (reactive compatibilization) during melt mixing in an internal Haake mixer. The physical and mechanical properties of the TPE blends were investigated by the dynamic mechanical analysis (DMA) and tensile tests. The thermal behavior was characterized by differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA). The phase morphology of the blends was studied by scanning electron microscopy (SEM). Experimental results showed that, both static and dynamic mechanical properties of reactively-compatibilized and dynamically-vulcanized samples improved significantly compared with the virgin samples. The effect of dynamic-vulcanization and reactivecompatibilization on the mechanical properties revealed that the Young’s modulus and storage modulus increased with both improvement methods. SEM results showed that, dynamic-vulcanization and reactivecompatibilization methods improved the distribution of RR particles in HDPE matrix. Although both methods improved the thermal and mechanical properties of the HDPE/RR blends, dynamic-vulcanization was more effective and promising approach due to the higher properties of HDPE/RR blends prepared by this method.     

磁电CoFe2O4/BaTiO3纳米管的溶胶-凝胶模板法合成和表征

用溶胶-凝胶模板法合成了CoFe2O4/BaTiO3(CFO/BTO)复合纳米管, 管的直径约为100、200和300 nm, 其长度约为100 μm. X射线衍射(XRD)和选区电子衍射(SAED)都显示复合纳米管中同时存在尖晶石相的CoFe2O4 (CFO)和钙钛矿相的BaTiO3(BTO), 进一步的透射电子显微镜(TEM)研究证实合成的纳米复合物具有明显的管状结构. 磁、电研究表明, 该复合纳米管的磁性与纯CFO纳米管的磁性相当; 而铁电性与纯BTO纳米管的铁电性相当.     

Optimization of tensile properties of injection molded α-nucleated polypropylene using response surface methodology

Tensile properties are among the significant properties of isotactic polypropylene (iPP). The mechanical properties including the tensile properties are fairly dependent on the overall crystallinity and crystallite size and their distribution in molded product, type of crystal structure and testing conditions. In presence of α-nucleating agents, the crystallization rate and onset temperature of isotactic PP increase. In this paper, the role of externally added commercial α-nucleating agent HPN-20E (Milliken Inc.) on tensile properties was investigated with respect to tensile properties of pure iPP. The experimental part includes the use of design of experiment (DoE) - response surface methodology (RSM) with central composite design (CCD) having three factors namely mold temperature, melt temperature and injection rate. Two levels of each factor with six centre points and five numbers of replicates were selected. The nucleating agent, HPN-20E, was added 1.0% by wt. in iPP (mfr 11.0 g/10min) using a lab scale co-rotating twin screw extruder. The compounded pellets were dried at 85 °C in a circulating hot air oven for 24 h. The tensile samples (ASTM-638D, type-I) were molded on a micro-injection molding machine (make BabyPlast, Italy). The samples were tested for tensile properties on a universal testing machine (make Lloyds, USA). The measured responses were tensile strength (MPa), Young's modulus (MPa) and work to break (N.mm). The same experimental procedure was also followed for pure iPP and same responses were measured to set the baseline of experiment. The analysis of variance (ANOVA) tests unearth that mold and melt temperatures are highly interacting in nature. That is why previous attempts based on traditional way of varying one parameter at a time were not so successful to relate tensile properties with injection molding variables. The RSM tests resulted into useful quantitative relationship between the tensile properties and injection molding process variables.     

Properties of radiation‐modified blends of polyethylene with elastomers and liquid crystalline copolyester

The results are given on the effect of γ‐irradiation on properties of blends of high and low‐density polyethylene (HDPE, LDPE) with elastomers ‐ethylene/propylene/diene rubber (EPDM) and chlorinated polyethylene (CPE), and thermotropic liquid crystalline polymer (LCP). The morphological, thermal, mechanical properties (including thermosetting properties) and adhesion properties of blended composites were investigated. A special attention was paid to the applicability of the blends as thermosetting materials (TSM). The LCP used was a copolyester of poly(ethylene terephthalate) with p‐(hydroxybenzoic acid) in the ratio 40 : 60. It was found that addition of LCP essentially influenced the thermomechanical and adhesion properties of PE composites, irradiated up to the absorbed dose 150 kGy, as well as the dimensional stability of thermosetting products, made from polyethylene/elastomer mixtures. The results show that such ternary blends considerably improve the exploitation conditions of irradiated polyethylene and useful thermosetting materials can be obtained.     

Universal relation for size dependent thermodynamic properties of metallic nanoparticles

The previous model on surface free energy has been extended to calculate size dependent thermodynamic properties (i.e., melting temperature, melting enthalpy, melting entropy, evaporation temperature, Curie temperature, Debye temperature and specific heat capacity) of nanoparticles. According to the quantitative calculation of size effects on the calculated thermodynamic properties, it is found that most thermodynamic properties of nanoparticles vary linearly with 1/D as a first approximation. In other words, the size dependent thermodynamic properties P(n) have the form of P(n) = P(b)(1 -K/D), in which P(b) is the corresponding bulk value and K is the material constant. This may be regarded as a scaling law for most of the size dependent thermodynamic properties for different materials. The present predictions are consistent literature values.     

Interpenetrating Polymer Networks of Uralkyd Resin Based on Hydrogenated Castor Oil and Poly(Butyl Acrylate)

Abstract

Semi‐ and full‐interpenetrating polymer networks (IPNs) of uralkyd (UA) resin based on hydrogenated castor oil and poly(butyl acrylate) (PBA) were prepared by the sequential mode of synthesis. These IPNs were characterized for their resistance to thermal behavior, swelling (%), and mechanical properties. The morphology of the IPNs was studied by scanning electron microscopy (SEM). The effect of the variations of the blend ratios on the above‐mentioned properties was examined. The mechanical properties significantly enhanced by increasing UA component in the blend. Full‐IPNs exhibited higher apparent densities, mechanical properties, and thermal stability than the corresponding semi‐IPNs.     

Structure,properties and interfacial interactions in poly(lactic acid)/polyurethane blends prepared by reactive processing

Polyurethane elastomers are promising candidates for the impact modification of PLA producing blends for example for biomedicine. Poly(lactic acid) (PLA)/polyurethane elastomer (PU) blends were prepared by reactive processing and physical blending as comparison. The blends were characterized by a number of techniques including microscopy (scanning electron microscopy, SEM, and atomic force microscopy, AFM), rotational viscometry, thermal (dynamic mechanical analysis, DMA), and mechanical (tensile) measurements. The analysis and comparison of the structure and properties of physical and reactor blends proved the successful coupling of the phases. Coupling resulted in more advantageous structure and superior mechanical properties compared to those of physical blends as confirmed by morphology, macroscopic properties and the quantitative estimation of interfacial interactions. Structural studies and the composition dependence of properties indicated the formation of a submicron, phase-in-phase structure which positively influenced properties at large PU contents. The results strongly support that reactive processing is a convenient, cost-effective and environmentally friendly technique to obtain blends with superior properties.     

Water-soluble light-emitting nanoparticles prepared by non-covalent bond self-assembly of a hydroxyl group functionalized oligo(p-phenyleneethynylene) with different water-soluble polymers

Water-soluble light-emitting nanoparticles were prepared from hydroxyl group functionalized oligos(p-phenyleneethynylene) (OHOPEL) and water-soluble polymers(PEG,PAA,and PG) by non-covalent bond self-assembly.Their structure and optoelectronic properties were investigated through dynamic light scattering(DLS) ,UV and PL spectroscopy.The optical properties of OHOPEL-based water-soluble nanoparticles exhibited the same properties as that found in OHOPEL films,indicating the existence of interchain-aggregation...     

Solution properties of poly(thiocarbonates)

For a series of poly(thiocarbonates) derived from bisphenol A several conformational and thermodynamic solution properties (partial specific volume, refractive index increment, effective dipole moment and characteristic ratio) were summarized. The effect of the structure, size and polarity of the different poly(thiocarbonates) side chains on these properties were analyzed. The high rotational freedom of the poly(thiocarbonate) chains, obtained from theoretical calculations, justifies the variation of the different properties experimentally obtained in the studied polymers.     

新型无机聚合物的设计合成、结构规律与性能研究*

本文以新型无机聚合物的合理合成和物理性能研究为主线, 总结3个系列具有新颖结构聚合物的组装与结构化学规律: (1)通过化学自组装法设计合成出系列金属-有机纳米笼、金属-有机纳米管和金属-有机纳米线.研究了合成金属-有机纳米分子的规律,开辟了一条合成金属-有机纳米分子的新途经.(2)通过结构调控、金属与桥联基元作用,把团簇单元活化后合成一维新型无机聚合物.在研究反应机理过程中分离和表征了大量的中间态产物,从而得到了这类聚合物合理合成的规律.(3)设计合成出二维层状(石墨型)、三维大孔(分子筛型)、金属聚硫及稀土与过渡金属混合4个系列新型的无机聚合物,总结了它们的结构规律和反应规律.在制备合成中既有结构单元自组装的反应又有设计合成的方法.通过系列化合物的结构表征和光、电或磁性能的研究, 探索出系列聚合物具有半导体性能和非线性光学性能,总结出聚合物的结构规律与基本结构单元组装的关系以及结构与性能的关系.     

The Surface and Thermodynamic Properties of Ethoxylated Sodium Monoalkyl Sulfosuccinate Surfactants

A series of ethoxylated sodium monooctyl sulfosuccinates [E(n)SMOSS] and ethoxylated sodium monolauryl sulfosuccinates [E(n)SMLSS] have different units of ethylene oxide (n = 9, 14, 23) were synthesized. The surface and thermodynamic properties of these surfactants have been compared with sodium dioctyl sulfosuccinate surfactant (SDOSS) as a commonly used surfactant. The surface tension measurements at 25, 35, 45, and 55°C were used to determine of the critical micelle concentration (CMC) and surface active properties of these surfactants. The effect of the ethylene oxide (EO) unit and the alkyl chain length on the surface properties for the prepared surfactants was studied. The results show that the ethoxylated sodium monoalkyl sulfosuccinates generally have lower values of CMC than that of sodium dioctyl sulfosuccinate. The values of surface active parameters indicate that the ethoxylated sodium monooctyl sulfosuccinates and ethoxylated sodium monolauryl sulfosuccinates surfactants have adsorption properties better than the sodium dioctyl sulfosuccinate surfactant as a resulted presence of ethylene oxide in molecules of the prepared surfactants. The thermodynamic parameters show that the (EO) unites in the chemical structure of ethoxylated sodium monoalkyl sulfosuccinate surfactants improve their micellization and adsorption properties.     

Multiresponsive supramolecular gels constructed by orthogonal metal–ligand coordination and hydrogen bonding

Macromonomers bearing tridentate 2,6-bis(1,2,3-trizol-4-yl)pyridine (BTP) ligand unit synthesized via CuAAC “click” chemistry in the middle of the chain and two ureidopyrimidinone (UPy) motifs on the ends linked to the central BTP unit via PEGs of various lengths were synthesized and used for the study of gelation both with and without the presence of Eu(III) ions. Various interesting gelation behaviors were found. Gels exhibited various multi-responsive properties, including photoluminescence, mechanoresponsive properties, self-healing abilities, thermorepsonsive properties and chemoresponsive properties. The different gelation abilities and multi-responsive properties for different systems were shown to be resulted from difference in PEG linker lengths and the introduction of orthogonal metal–ligand coordination and hydrogen bonding interactions. The selective responsiveness to different chemicals would allow the development of modular sensory systems that utilize a combination of orthogonal supramolecular interactions.     

Properties and hydrolysis of PLGA and PLLA cross-linked with electron beam radiation

Radiation has been used as a processing tool to modify the properties of polymers. The aim of this study is to understand how electron beam radiation, together with pentaerythritol tetraacrylate (PTTA) as a tetra-functional monomer, can alter the properties (i.e. thermal and mechanical) and hydrolysis rates of PLGA and PLLA. The effects of radiation dose and PFM concentration on the physical properties of the polymers were investigated. The results showed that upon irradiation PLGA and PLLA cross-linked, and an increased in gel content was observed. Glass transition temperature (T_g) and mechanical properties of the polymers also increased. Cross-linked PLGA and PLLA samples were found to retard hydrolytic degradation. The mechanical properties of these polymers were also unaffected by hydrolysis. In summary, PLGA and PLLA cross-linked with PTTA were found to have enhanced mechanical properties and were able to retard hydrolytic degradation.