Effects of graft length and density of well‐defined graft polymers on the thermoresponsive behavior and self‐assembly morphology

A series of well‐defined thermoresponsive graft polymers with different lengths and graft densities, poly(glycidyl methacrylate)‐graft‐poly(N‐isopropylacrylate) (PGMA‐g‐PNIPAM), were successfully prepared by combination of controlled/living free radical polymerization and click chemistry. Effects of grafting length and density on the thermoresponsive behavior, aggregating mean diameter, and self‐assembly morphology are systematically investigated. The thermosensitive characteristics of graft polymers in aqueous solution prove that the length and graft density had positive co‐relationship with the lower critical solution temperature value and mean diameter of micelles as well as the size distribution, while the effect of graft length of polymers is more significant than that of density. Transmission electron microscopy analysis shows that the conformations of PGMA₄₅‐g‐PNIPAM₂₀ and PGMA₄₅‐g‐PNIPAM₄₆ with longer length and bigger grafting density in aqueous solutions are spherical nanoparticles with the increasing trend of the diameters, while that of PGMA₄₅‐g‐PNIPAM_{(73, 50%)} shows a spherical‐like morphology, which indicates that the graft length and density have a significant effect on the mean diameter of micelle but not on the self‐assembly morphology. These results reveal that to obtain desired thermoresponsive behavior and self‐assembly morphology of functional polymers, it is essential to design and fabricate the structure of graft polymers with proper length and graft density. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2442–2453     

Progressive transition from resonant to diffuse reflection in anisotropic colloidal films

The synthesis and characterization of highly ordered three‐dimensional photonic crystals have been the subjects of intense study over the past two decades due to the unique ability of these structures to control light at the nanoscale. Building on that work in recent years, increasing interest is now focused on the unique optical properties of disordered and quasi‐ordered photonic structures. We present a study of the effects of shape anisotropy and disorder on the specular reflection properties of polymer‐based colloidal films comprised of rod‐shaped subunits of varying aspect ratio. We characterize the specular reflectance properties of these films as a function of their increasing levels of disorder, demonstrating progressive transition from resonant reflection to diffuse reflection. The onset of the diffuse reflection is governed by particle size. © 2014 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys. 2014 , 52, 611–617     

Preparation of an Organometallic Molecular Square by Self‐Assembly of Phosphorus‐Containing Building Blocks

Molecular squares are among the most common supramolecular architectures, but phospha‐organometallic complexes have not been used as building blocks for this type of structure. Herein we describe the formation of the molecular square [Au{Co(P₂C₂tBu₂)₂}]₄ ( 1 ) by the self‐assembly of anionic 1,3‐diphosphacyclobutadiene cobalt complexes and gold(I) cations. The X‐ray crystallographic determination of the molecular structure of 1 is complemented by solid‐state ³¹P and ¹³C NMR investigations. High‐level DFT calculations confirm the assignment of the ³¹P and ¹³C NMR resonances.     

人造金刚石生长中的温度控制

 本文讨论了与腔体组装方法、温度梯度和边界条件等有关的温度控制问题及其对金刚石生长的影响。     

Nonbubble‐Propelled Biodegradable Microtube Motors Consisting Only of Protein

This paper describes the synthesis of protein microtube motors having a urease interior surface and highlights their nonbubble‐propelled behavior driven by enzymatic reaction (urea→NH₃ and CO₂). The precursor microtubes were prepared by layer‐by‐layer assembly using a track‐etched microporous polycarbonate membrane. Immobilization of a urease on the internal wall was accomplished using avidin–biotin interaction. The tubules swam smoothly in an aqueous media containing a physiological concentration of urea. Each tubule was rotating laterally while moving forward. It is remarkable that the microtubes were digested completely by proteases, demonstrating perfect biodegradability.     

Water‐soluble Glucosamine‐coated AIE‐Active Fluorescent Organic Nanoparticles: Design,Synthesis and Assembly for Specific Detection of Heparin Based on Carbohydrate–Carbohydrate Interactions

Two water‐soluble carbohydrate‐coated AIE‐activate fluorescent organic nanoparticles TPE3G and TPE4G were designed and synthesized for the detection of heparin. Different from the reported strategy, we not only utilized the general detection mechanism of electrostatic interactions, but also introduced the concept of carbohydrate‐carbohydrate interactions (CCIs) to enrich the detection mechanism of heparin. TPE3G can serve as an efficient “turn‐on” probe with higher selectivity towards heparin than TPE4G . TEM studies revealed that the micro‐aggregated TPE3G was encapsulated with the heparin chain to form a complex self‐assemblied composite and emits strong fluorescence. It is believed that the results illustrated in this study provide a novel strategy based on CCls to design water‐soluble and more efficient bio‐probes for various biological and clinical applications.     

Integration of Sequential Reactions in a Continuous Flow Droplet Reactor: A Route to Architecturally Defined Bimetallic Nanostructures

Microreactors for nanoparticle (NP) synthesis offer advantages over batch reactions in terms of scale‐up and integration with online analyses. Herein, two microreactors (i.e., a duo‐microreactor) are integrated to achieve sequential reactions for the synthesis of bimetallic NPs with architectural control. The generality of the duo‐microreactor is shown with the synthesis of branched Pd‐Pt NPs and core@shell Pd@Au NPs, both achieved by synthesizing Pd nanocubes in the first part of the duo‐microreactor and then using those nanocubes downstream as seeds for Pt or Au deposition. Control of the dimensions of these NPs is further demonstrated and achieved by tailoring metal precursor concentrations inline. This microreactor methodology is anticipated to be applicable to other bimetallic NP systems.     

Design of a 6-DOF force device for virtual assembly (FDVA-6) of mechanical parts

Among different interaction modalities, force feedback is one of the key technologies to increase the interactivity and immersion of a virtual assembly process. This paper presents a 6-DOF force device with its forward kinematic analysis, workspace simulation, and gravity compensation. To evaluate the device, a prototype system is developed and a case study is conducted to assemble a mechanical product. The users have given positive feedback on the gravity compensation implemented and the general performance of the device.