Wavelength Orthogonal Photodynamic Networks

The ability of light to remotely control the properties of soft matter materials in a dynamic fashion has fascinated material scientists and photochemists for decades. However, only recently has our ability to map photochemical reactivity in a finely wavelength resolved fashion allowed for different colors of light to independently control the material properties of polymer networks with high precision, driven by monochromatic irradiation enabling orthogonal reaction control. The current concept article highlights the progress in visible light-induced photochemistry and explores how it has enabled the design of polymer networks with dynamically adjustable properties. We will explore current applications ranging from dynamic hydrogel design to the light-driven adaptation of 3D printed structures on the macro- and micro-scale. While the alternation of mechanical properties via remote control is largely reality for soft matter materials, we herein propose the next frontiers for adaptive properties, including remote switching between conductive and non-conductive properties, hydrophobic and hydrophilic surfaces, fluorescent or non-fluorescent, and cell adhesive vs. cell repellent properties.     

Unified study of the different physical properties of amorphous polymers

Uptil now it has not been possible to explain the different physical properties of amorphous polymers using a model based on a single conceptual scheme. In this paper, a phenomenological model is proposed which tries to explain the mechanical, optical and thermal properties (both thermal conductivity and expansivity) of amorphous polymers. The model has similarities with the composite model, proposed by the present authors, which has proved to be successful in interpreting the different physical properties of semicrystalline polymers. The present model considers the bulk form of the polymer as an aggregate of microscopic units possessing intrinsic physical properties. On drawing, the development of anisotropy in different physical properties is supposed to be due to the development of preferred orientation of these units. The development of the preferred orientation has been estimated directly from birefringence data. The agreement between the calculated and experimental values of the elastic modulus, thermal conductivity and thermal expansivity of PVC, PMMA and PS is found to be reasonable good.     

Mesoscale simulation of water

A coarse-grained model for water is developed which maps five water molecules onto one bead. The coarse-grained potential is derived by iteratively matching the radial distribution function of water in the coarse-grained and target models. It is shown that the coarse-grained model has the optimal balance between computational efficiency and accuracy in structural properties. The model has been used to calculate a number of static and dynamic properties, including the density, isobaric thermal expansivity, isothermal compressibility, surface tension, and diffusion coefficient of water. The effect of coarsening on these properties has been discussed. It is shown that while the present coarse-grained model well describes the structural properties of water, expectedly it has a much faster dynamics than the corresponding atomistic models.     

硅橡胶、聚氨酯医用材料

聚氨酯具有良好的生物相容性、优异的力学性能、易成型加工、性能可控等优点;硅橡胶具有生理惰性和生物相容性好等优点,这使他们在医学方面有着广泛的应用。本文主要是在介绍了硅橡胶和聚氨酯的结构、特性的同时,又分别介绍了它们在医学方面的发展情况及根据不同用途制成的制品,并对它们在将来医疗中的发展进行了展望。     

Structurally and conformationally defined small methyl polysilanes

Possessing the property of sigma-bond electron delocalisation, polysilanes are a class of compounds with unique properties. In recent years major progress has been achieved in the theoretical understanding and the synthesis of polysilanes. Much insight into the connection between conformation and electronic properties has been gained from studies of defined small polysilane molecules. The transition from Wurtz type coupling reactions to the stepwise construction of polysilane molecules employing silyl anions as key intermediates has permitted access to defined compounds with a higher degree of structural complexity. Besides this, several methods have been developed to control the conformational properties and thus gain control over the electronic properties of polysilanes.     

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.     

A comprehensive investigation in determination of nanofluids thermophysical properties

In recent years, research on heat transfer and related equipment has been one of the topics of interest in many different industries. The use of conventional fluids in heat transfer due to their low thermal properties has created problems in this area, so the use of nanofluids in many cases has been a solution to overcome this problem. The parameters affecting the thermophysical and thermal properties of nanofluids are temperature, concentration, size, shape, pH, surfactant and ultrasonic time, among which temperature and concentration have the greatest effect. Existing models and studies in the field of nanofluids are limited to the type of nanoparticles and base fluids and their operating range, and there is no comprehensive model for predicting thermal properties. In the present study, models and theories regarding the determination of thermal conductivity of nanofluids and other thermophysical properties have been comprehensively compiled and the mechanisms for increasing the thermal properties as well as the effective parameters and the effect of each of them on improving the properties are presented. In general, the results showed that thermal properties improve with increasing concentration and temperature. Finally, the role of nanofluids effect on thermal performance in the heat exchangers is studied and the results are summarized.     

Photoinduced shape fixity and thermal-induced shape recovery properties based on polyvinyl alcohol bearing coumarin

In this paper, polyvinyl alcohol (PVA) bearing coumarin with different degrees of substitution (DS) are synthesized by esterifying hydroxyl of PVA with 7-carboxylmethoxycoumarin. The grafted polymer has photosensitive property and presents photocrosslinking due to the photodimerization between pendant coumarin groups, which affords PVA–coumarin sample photoinduced shape fixity properties. PVA–coumarin can be cross-linked after being illuminated under UV light of 360 nm; this provides the possibility that the sample has shape memory properties only if the cross-linking extent is suitable. The shape memory properties were induced by thermal as most shape memory polymer do. In fact, the shape fixity and recovery has strong relationship with DS, irradiation time, and thickness of sample. The effect of DS on the grafted polymer structure and properties has been studied by differential scanning calorimetry, thermogravimetric analysis, and UV spectra.     

Prediction of thermodynamic properties of sodium dodecyl sulfate aqueous solutions through the hetero-SAFT equation of state

A special version of statistical associating fluid theory (SAFT), the so-called hetero-segmented SAFT equation of state, has been extended to calculate the thermodynamic properties of sodium dodecyl sulfate aqueous solutions. The predicted properties were included the vapor pressure as well as second thermodynamic properties, such as speed of sound. Evaluation of the model has been done through comparison of the calculated vapor pressure with experimental data in the range of 298.15–313.15 K. The hetero-SAFT model is found to be able to correctly describe the thermodynamic derivative properties as well as pVT and VLE properties of ionic surfactant solutions.     

5083铝合金在海水中的腐蚀电化学行为及活性氯影响研究

采用动电位极化、循环极化和全浸腐蚀试验方法,研究了5083铝合金在静止海水中的腐蚀电化学性能以及活性氯的影响.结果表明,在本文设置的防污活性氯浓度范围(0.2～0.5mg/L)内,活性氯对铝合金的阴极和阳极电化学极化以及腐蚀行为没有明显影响,并可提高铝合金的耐点蚀能力,海水的pH值对铝合金的腐蚀具有显著的影响.该研究为海水中5083铝合金的防腐防污提供了依据.     

Viscoelastic properties of linear low density polyethylene melts

The importance of linear low density polyethylene (LLDPE) is being rapidly felt. The combination of favourable production economics and excellent product performance characteristics has enabled this new plastic to gain acceptance for a wide variety of applications. No studies on the rheological properties of LLDPE exist to date. The viscous and elastic properties of this new polymer has now been investigated and unified curves for viscosity and normal stress differences are given. The temperature dependence of the rheological properties of LLDPE has also been studied.     

Synthesis and application of inorganic/organic composite materials

A new type of inorganic-organic composite has been developed using organic monomeric or polymerizable silanes (with appropriate organic groupings like double bonds or epoxides) as monomers or in situ prepared or separately added nano-scale ceramic or metal particles. Due to the small size of the particulate phase, these composites are still highly transparent but show properties at least partially to be attributed to the inorganic phase. The introduction of special functions into these materials has been used for the fabrication of interesting functions like non-linear optical properties, low surface free energy coatings, controlled release properties or special mechanical properties (scratch resistance).     

Engineering proteins with tailored nanomechanical properties: a single molecule approach

Elastomeric proteins underlie the elasticity of natural adhesives, cell adhesion and muscle proteins. They also serve as structural materials with superb mechanical properties. Single molecule force spectroscopy has made it possible to directly probe the mechanical properties of elastomeric proteins at the single molecule level and revealed insights into the molecular design principles of elastomeric proteins. Combining single molecule atomic force microscopy and protein engineering techniques, it has become possible to engineer proteins with tailored nanomechanical properties. These efforts are paving the way to design artificial elastomeric proteins with well-defined nanomechanical properties for application in nanomechanics and materials sciences.     

Features of the influence of nanosilicates on the change of properties of different polymer and adhesive systems

The effect of nanosilicates on various polymer systems—thermoplastic and rubber—has been studied. The possibility of optimizing the fireproof properties of these systems has been shown by modifying them with nanosilicates while retaining and, in some cases, increasing their physicomechanical properties.     

聚乳酸纳米复合材料的研究进展

聚乳酸是一种重要的可生物降解/吸收高分子材料,广泛地用作可降解塑料、纤维和生物材料,市场前景广阔.它具有与聚烯烃相当的力学强度和加工性能,但耐热性和抗冲性较差.为满足各种应用的需要,其热性能、力学性能和气体阻隔性等尚需进一步提高.通过与无机纳米材料复合的方法,可以明显地提高聚乳酸的性能.本文介绍了近年来聚乳酸有机-无机纳米复合材料的制备、结构与性能等方面的研究进展,对三者的相互关系进行了评述,并对今后的研究方向进行了展望.     

热固性丙烯酸酯液晶

介绍了热固性丙烯酸酯液晶单体的合成路线、取向方式和聚合工艺，叙述了数种影响热固性丙烯酸酯液晶单体及其聚合物性能的主要因素，简要介绍了国内外热固性丙烯酸酯液晶研究的最新动向。     

Effect of polysulfone modification techniques on the properties of polymer-silicate nanocomposites

An effect of different methods of structural modification of the heat-resistant amorphous polysulfone with layered silicate montmorillonite on the properties of the resulting polymer-silicate nanocomposites has been studied. Comparative evaluation of the technological, physical, mechanical, thermal, and rheological properties of the nanocomposites has been performed.     

Development of phosphorus-boron-nitrogen-containing modifier for elastomeric compositions

Synthesis of phosphorus-boron-nitrogen-containing modifier (PEDA) has been performed, and the properties thereof have been studied. It has been shown that introduction of PEDA as a modifying additive in elastomeric compositions makes it possible to improve their adhesive and fire–heat protective properties.     

溴代作用对竹红菌素分子性质影响的理论研究

用AM1方法对红菌素（包插甲素和乙素）与它们的溴代物进行了量子化学对比计算,得到了生成热,前线轨道能级及偶极矩等,讨论了溴代作用对竹红菌素分子性质的影响。     

The unusual physicochemical properties of azulene and azulene-based compounds

This review shows the unusual physicochemical properties and wide application of azulene and its derivatives. The recent synthesis strategies of kinds of substituted azulene are also listed.