Transparent film materials with excellent mechanical and thermal properties were elaborated by drying a latex suspension of armored polymer/Laponite composite particles. Low‐temperature TEM observation of ultrathin cross‐sections of the films indicated a unique network morphology characterized by a “honeycomb” distribution of the Laponite platelets remindful of the original particles morphology.
Summary: Self‐oscillating polymers and nano‐gel particles consisting of N‐isopropylacrylamide and the ruthenium catalyst of the Belousov‐Zhabotinsky reaction have been prepared. In order to clarify the crosslinking effect on the self‐oscillating behavior, the phase transition behaviors were investigated by measuring the transmittance and the fluorescence intensity of the polymer solution and the gel bead suspension. Cooperative effects due to crosslinking will play an important role for the design of nanoactuators.
Chemical structure of poly(NIPAAm‐co‐Ru(bpy)3). 相似文献
A numerical method for simulating spinodal decomposition in ternary systems with order‐of‐magnitude differences in diffusion coefficients is presented. The method has been partially verified by molecular dynamic simulations and gives results equivalent to the standard technique when the diffusivities are equal. A two‐dimensional simulation of an asymmetric polymer/polymer/polymer system reproduces an experimentally observed bimodal distribution of dispersed‐phase particle sizes. The ripening exponent for the larger particles is near the expected value of 0.33, but that for the smaller particles is only about 0.1. The method was also used for a polymer/polymer/solvent system.
Au nanoparticles (NPs) and polymer composite particles with phase‐separation structures were prepared based on phase separation structures. Au NPs were successfully synthesized in amphiphilic block‐copolymer micelles, and then composite particles were formed by a simple solvent evaporation process from Au NPs and polymer solution. The phase separated structures (Janus and Core‐shell) were controlled by changing the combination of polymers having differing hydrophobicity.
Summary: New polymer gelators consisting of poly(propylene glycol) or poly(ethylene glycol) and L ‐lysine‐based low‐molecular‐weight gelators have been developed. These polymer gelators were synthesized according to a simple procedure with high reaction yield, and formed organogels in many organic solvents. The organogelation mechanism was proposed from the transmission electron microscopy and FTIR spectroscopy studies.
Structures of the polymer gelators synthesized here. 相似文献
Summary: We describe an interesting approach to the fabrication of wettability gradients from hydrophobicity to superhydrophobicity in low‐density polyethylene (LDPE) films by first forming high porosity surfaces and placing the specimens onto linear temperature gradients. While the polymer chosen for the study is non‐polar, its microporous layer provides sufficient superhydrophobicity. Lateral gradient heating of the layer results in partial melting of the polymer and correspondingly decreases porosity thus decreasing hydrophobicity.
We report the formation of poly(propylene) spherical and ellipsoidal particles templated by carbon nanotubes via solution crystallization. With an increase in nanotube loading, the particle shape changes from sphere to ellipsoid. In the intermediate concentration range, both spherical and ellipsoidal shapes coexist. The particle size decreases with an increase in nanotube loading.
A ‘grafting‐from’ approach to synthesize microparticle‐supported conjugated polyelectrolyte brushes is presented. Poly(3‐bromohexylthiophene) is selectively grown from monodisperse organosilica microparticles by surface‐initiated Kumada catalyst‐transfer polycondensation (SI‐KCTP) and then ionizable amino groups are introduced by a two‐step polymer analogous transformation. Optical properties of the resulting microparticle‐supported conjugated polyelectrolyte brushes were found to be dependent on the surrounding chemical environment and thus the particles are promising materials for sensor applications.
An order–order transition (OOT) in the sequence of a hexagonally arranged core–shell cylinder to a double‐hexagonally arranged dot in polystyrene‐block‐poly(butadiene)‐block‐poly(2‐vinylpyridine) (SBV) triblock copolymer thin films is reported to be induced upon exposure to a solvent vapor that is strongly selective for the two end blocks. These two kinds of hexagonally arranged structures could form when the film thickness is 44, 123, and 223 nm. When the film thickness is decreased to 13 nm, the ordered structure is absent. The sizes of the core–shell cylinder structures formed with the same annealing time in films of different thickness are compared to address the effects of film thickness on the phase structure. The mechanism is analyzed from the total surface area of the blocks and the effective interaction parameter in the solvent vapor.
Rheological and solid‐state physical properties of blends containing high‐density polyethylene (HDPE) and a polyampholyte derivative (PE‐g‐PA) are assessed along with their onium ion‐exchanged montmorillonite clay (NR‐MM) nanocomposites. Strong deviations from the log‐additivity rule of zero‐shear viscosity, combined with synergistic behavior in tensile moduli, are consistent with a multi‐phase blend morphology. While this affects clay dispersion in filled blends, PE‐g‐PA/HDPE based nanocomposites are shown to exhibit a favorable balance between material stiffness and ductility.
A novel pH‐switchable macroscopic assembly is reported using alginate‐based hydrogels functionalized with host (α‐cyclodextrin, αCD) and guest (diethylenetriamine, DETA) moieties. Since the interaction of αCD and DETA is pH sensitive, the host hydrogel and guest hydrogel could adhere together when the pH is 11.5 and separate when the pH is 7.0. Furthermore, this pH‐controlled adhesion and dissociation shows a good reversibility. The host and guest polymers have good biocompatibility; therefore, this pH‐sensitive macroscopic assembly shows great potential in biotechnological and biomedical applications.
Summary: A simple method to prepare surfactant‐free and solvent‐free semiconducting polymer particles by using an environmentally benign supercritical carbon dioxide (scCO2) process is reported. The process of the rapid expansion of supercritical solutions (RESS) is used to produce spherical particles of poly[2‐(3‐thienyl)acetyl 3,3,4,4,5,5,6,6,7,7,8,8,8‐tridecafluorooctanoate] (PSFTE), 50–500 nm in size, from 0.1–0.5 wt.‐% PSFTE solutions in CO2 at pre‐expansion temperatures of 40 °C and pre‐expansion pressures of 276 bar.
An FESEM image of PSFTE particles produced by the RESS process with CO2. 相似文献
