反应注射成型体系中的界面现象：I.实验研究

在光学显微镜下，对反庆注射成型体系中反应诱导混合现象进行了系统的考察。研究结果表明，界面上的反应是产生自动混合的关键原因，界面上的反应诱导混合促进了流体在微观尺度上的进一步混合，反应和的活性，催化剂，反应温度及生成物增长曲线，可表征反应诱导混合能力。     

乳状液界面膜厚度与结构

对以混合非离子表面活性剂所乳化的82—123后上蜡乳状液用电镜法、粘度法,壳层法和表面张力法等四种不同方法研究了其界面膜的厚度,所得结果比较一致。同时论证了多层界面膜的结构模型。     

A new and evolving paradigm for biocompatibility

We propose that the mechanical property of the interface between an implant and its surrounding tissues is critical for the host response and the performance of the device. The interfacial mechanics depends on several different factors related to the physical shape of the device and its surface as well as properties of the host tissue and the loading conditions of the device and surrounding tissue. It seems plausible that the growth of the fibrotic tissue to support mechanical loads is governed by the same principles as depicted by Wolfs' Law for bone. Of course, biocompatibility will have different implications depending on which vantage point we look at the host-material interface. Another implication is that only limited aspects of biocompatibility is measurable with current in vitro tests and that the elicited host response in vivo models remains crucial for evaluation of medical devices and tissue engineering constructs.     

Amorphous oxide alloys as interfacial layers with broadly tunable electronic structures for organic photovoltaic cells

In diverse classes of organic optoelectronic devices, controlling charge injection, extraction, and blocking across organic semiconductor–inorganic electrode interfaces is crucial for enhancing quantum efficiency and output voltage. To this end, the strategy of inserting engineered interfacial layers (IFLs) between electrical contacts and organic semiconductors has significantly advanced organic light-emitting diode and organic thin film transistor performance. For organic photovoltaic (OPV) devices, an electronically flexible IFL design strategy to incrementally tune energy level matching between the inorganic electrode system and the organic photoactive components without varying the surface chemistry would permit OPV cells to adapt to ever-changing generations of photoactive materials. Here we report the implementation of chemically/environmentally robust, low-temperature solution-processed amorphous transparent semiconducting oxide alloys, In-Ga-O and Ga-Zn-Sn-O, as IFLs for inverted OPVs. Continuous variation of the IFL compositions tunes the conduction band minima over a broad range, affording optimized OPV power conversion efficiencies for multiple classes of organic active layer materials and establishing clear correlations between IFL/photoactive layer energetics and device performance.Solar to electrical energy conversion technologies have received great attention as abundant and sustainable resources (1–5). The diffuse nature of solar energy requires low-cost, large-area devices while maintaining high power conversion efficiency (PCE) (3). As a universal design strategy, many of the emerging thin film photovoltaic (PV) technologies such as bulk heterojunction (BHJ) organic, perovskite, quantum dot (QD), and CIGS (Cu-In-Ga-Se) solar cells are fabricated using a trilayer architecture, where light absorbers are sandwiched between two electrodes coated with various interfacial layers (IFLs) (6–9). Stringent requirements govern ideal IFL materials design. Energetically, their respective band positions should match those of the photoinduced built-in potentials to provide energetically continuous carrier transport pathways and to accommodate the maximum allowed output voltage. In recent reports, PV performance enhancement via IFL energetic tuning has been demonstrated for very specific BHJ organic, QD, and perovskite cell compositions (6, 8, 10, 11). However, true IFL energetic tunability has not been achieved and offers a challenging opportunity to optimize device performance.Fabricable from energetically diverse organic active layers, organic photovoltaics (OPVs) provide an excellent test bed for tuning IFL energetics and are the subject of this study. The basic BHJ OPV architecture contains a mesoscopically heterogeneous and isotropic, phase-separated donor–acceptor blend—a strategy to overcome the relatively short exciton diffusion lengths (∼10 nm) (2, 12, 13), sandwiched between hole-transporting (HT) and electron-transporting (ET) IFLs (2). These IFLs function to accommodate the cell built-in fields, to assist carrier extraction, and to suppress parasitic carrier recombination (2, 14–16). Indeed, studies on interfacial modification of HT electrodes verify that changing the band alignment profoundly affects OPV open circuit voltage (V_oc) and carrier lifetimes (17). Over the past decade, extensive efforts have focused on band gap engineering of OPV active layer materials, mainly by tuning the donor material highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energetics to enhance built-in potentials and maximize photon harvesting efficiency (18, 19). Consequently, compatible HT IFLs have been developed to tune their valence band minima (VBM) or HOMO energies to match that of a specific organic donor. In contrast, because of historical limitations in acceptor diversity, far less effort has been devoted to developing ET IFLs—to date, a few ET IFLs have been used in inverted OPVs, primarily TiO_x, ZnO_x, several polymers, self-assembled monolayers, and cross-linked fullerenes (11, 14–16, 20–24). Nevertheless, most of these materials have fixed band edge positions, significantly limiting their adaptability to emerging OPV materials systems with acceptors having different LUMO energies. The recent emergence of promising nonfullerene OPV acceptors—n-type small molecules and polymers having diverse electronic structures (1, 25–29)—illustrates the need for a design strategy to create ET IFLs with broadly tunable energy levels. Furthermore, moving from oxides, to polymers, to self-assembled materials incurs large, unpredictable variations in surface chemistry, compounding the challenge in energy level positioning. Also, factors such as adsorbates, interfacial dipoles, molecular orientations, and interface states confound predictable IFL/organic semiconductor interfacial energy alignment (30) and challenge precise, continuous energy level tuning for traditional organic semiconductor or vacuum deposited oxide IFLs. Thus, straightforwardly prepared ET IFL materials having broadly tunable conduction band minima (CBM) and work functions for adjusting band alignment would provide generalizable means to optimize current generation OPV performance and accommodate emerging organic donor/acceptor pairs.We report here an ET IFL design strategy using solution-processed amorphous metal oxide alloys. Continuous CBM tunability is achieved by alloying two or more electronically dissimilar oxides, realized by precursor compositional adjustment. We show that band edge energies can be dialed-in for indium–gallium oxide (a-IGO) and gallium–zinc–tin oxide (a-GZTO) (Zn:Sn = 1:1) IFLs, providing CBM tunability over 3.5–4.6 eV. The resulting films have excellent chemical/environmental stability, conformal coating, and good electron mobilities, ideal for solar cells as verified with several OPV classes where the IFL CBMs are systematically tuned to optimize performance. This includes acceptors with LUMO energies from −4.1 eV to −3.5 eV. To our knowledge, these results are the first example of band structure tuning in solution-processed amorphous oxide IFLs. Furthermore, the amorphous character enables flexible OPV fabrication by coating amorphous oxide electrodes.Note that the oxide CBM energies and acceptor LUMO energies are verified here by low-energy inverse photoemission spectroscopy (LEIPS) which provides excellent energy resolution and precision (∼0.1 eV) and negligible sample damage to organics (31, 32) (see more in SI Appendix, Figs. S2 and S3). It will be seen that OPV PV metrics closely track the IFL CBMs and can be optimized for the five BHJ OPV material sets in Fig. 1B, PBDT-BTI:PDI-CN2; PTB7:PC₇₁BM [poly[[4,8-bis[(2-ethylhexyl)oxy]-benzo[1,2-b:4,5-b'']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)-carbonyl]-thieno[3,4-b]thiophenediyl]]:[6,6]-phenyl-C71-butyric acid methyl ester)] (33); PTB7:ICBA (PTB7: indene-C60 bisadduct) (34); PTB7:P(NDI2OD-T2) [PTB7: poly[N,N''-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5′-(2,2''-bithiophene)] (35); and PDTG-TPD:PC₇₁BM (poly-dithienogermole-thienopyrrolodione: PC₇₁BM) (18).Open in a separate windowFig. 1.Tuning bottom electrode (ITO) interfacial layer (IFL) energy levels for inverted organic solar cells. (A) Inverted OPV and cross-sectional TEM image of an as-prepared ITO/a-IGO (50% Ga)/PTB7:PC₇₁BM/MoO₃/Ag solar cell. Insets show higher-resolution image and nanobeam electron diffraction pattern of a-IGO. (B) Chemical structures of the organic semiconductors used in this study and energy levels of the various inverted organic solar cell inorganic and organic components.     

Mechanical Properties of Cement Reinforced with Pristine and Functionalized Carbon Nanotubes: Simulation Studies

Concrete is well known for its compression resistance, making it suitable for any kind of construction. Several research studies show that the addition of carbon nanostructures to concrete allows for construction materials with both a higher resistance and durability, while having less porosity. Among the mentioned nanostructures are carbon nanotubes (CNTs), which consist of long cylindrical molecules with a nanoscale diameter. In this work, molecular dynamics (MD) simulations have been carried out, to study the effect of pristine or carboxyl functionalized CNTs inserted into a tobermorite crystal on the mechanical properties (elastic modulus and interfacial shear strength) of the resulting composites. The results show that the addition of the nanostructure to the tobermorite crystal increases the elastic modulus and the interfacial shear strength, observing a positive relation between the mechanical properties and the atomic interactions established between the tobermorite crystal and the CNT surface. In addition, functionalized CNTs present enhanced mechanical properties.     

Numerical Study on the Progressive Damage Behavior of the Interfacial Debonding between Shape Memory Alloy and Polymer Matrix

The shape memory alloy reinforced composites have promising application potential for aerospace, automotive and biomedical engineering, while the interfacial bonding performance between shape memory alloy and polymer matrix is crucial to the improvement on the mechanical properties. The interfacial bonding mechanical properties are not uniform on the interface between shape memory alloy and the polymer matrix due to the existence of internal defects. Based on the cohesive zone model, an innovative finite element model is proposed to simulate the progressive damage behavior of the interfacial debonding between shape memory alloy and polymer matrix. The good agreement between the numerical results and the available experimental results indicates the validation of the proposed model. The progressive damage and connection of different positions of the interface between shape memory alloy and polymer matrix result in the final interfacial debonding behavior. Further, the effects of the shape memory alloy length-diameter ratio and embedded depth on the interface performance between shape memory alloy and polymer matrix are investigated.     

表面活性物质对液液传质的影响Ⅱ．对Lewis槽传质的影响

在Ｌｅｗｉｓ槽中研究了表面活性物质对三种部分互溶液液体系传质速率的影响，并与单液滴传质实验结果进行比较。结果表明，表面活性物质对Ｌｅｗｉｓ糟和单液滴传质速率有类似的影响，对Ｌｅｗｉｓ的影响程度高于单液滴。     

Multicyclic Polyethers Derived from Tetra(bromomethyl)methane and Flexible Diphenols

Summary: Soluble multicyclic polyethers have been prepared by the polycondensation of tetra(bromomethyl)methane with various diphenols. The influence of the diphenol on the competition between cyclization and chain growth (yielding insoluble gels) is studied for feed ratios of 2/1 (a₂/b₄ monomer) and high conversions. With 4‐tert‐butylcatechol or 2,2′‐dihydroxy‐1,1′‐binaphthyl, mainly monomeric spiro‐cycles are formed. Soluble multicycles free of end‐groups are only obtained from α,ω‐bis(3‐hydroxyphenoxy) alkanes. The structure of the reaction products has been characterized by ¹H NMR spectroscopy and MALDI‐TOF mass spectrometry. As characteristic properties of the compact multicyclic structure, low solution viscosities in combination with high polydispersities are found. DSC measurements prove an amorphous character with glass‐transition temperatures in the range of 45–85 °C.

Formation of soluble multicyclic oligoethers.     

Polycondensation of Metal Salts of 6‐(2‐Chloroacetate)hexanoic Acid: A New Method to Synthesize Alternating Copolyesters Constituted by Glycolic Acid Units

A new copolyester was prepared from glycolic acid and 6‐hydroxyhexanoic acid units. The monomer was prepared by a thermal polycondensation method and its reactivity evaluated by means of DSC and IR spectroscopy. The driving force of the reaction was the formation of a metal chloride salt. Thus, the reactivity depended on the ionization potential of the alkaline cation; while the cesium salt started to polymerize at room temperature, the sodium salt did so only above 120 °C. The low reaction temperature and the absence of catalysts allowed transesterification and other secondary reactions to be avoided. DSC, optical microscopy and XRD techniques demonstrated that the new polymer was highly crystalline. The final molecular weight was sufficient to obtain fiber‐forming properties.

     

Stereocomplexes from Biosourced Lactide/Butylene Succinate‐Based Copolymers and Their Role as Crystallization Accelerating Agent

Biosourced co(polyester urethane)s containing different ratios of enantiomeric oligo(L ‐ or D ‐ lactide) (OLLA/ODLA) sequences and oligo(butylene succinate) (OBS) blocks (P(OD(L)LA‐b‐OBS)) are synthesized. Their stereocomplexation is confirmed by differential scanning calorimetry and X‐ray diffraction. The process is efficient independently on the OLA/OBS ratio and for OLLA/ODLA ratios from 2:3 to 3:2. The preformed stereocomplexes show remarkable crystallization accelerating efficiency when melt‐blended with a commercial PLLA in amounts from 2.5 to 10 wt%. Spectacular increase in the polyester matrix crystallinity (from 2 up to 42%) and crystallization rate (half‐time of ca. 3 min compared to ca. 30 min for the neat PLLA) is observed.