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991.
Suizhou Yang Ke Yang Aloke Jain Ramaswamy Nagarajan Jayant Kumar 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(11):938-941
A novel method for maskless micro-patterning of polymeric substrates is presented. First, an azobenzene functionalized polymer film is spin-coated on a Poly (ethylene terephthalate) (PET) sheet. Then surface relief structures are optically inscribed on the polymer film by interference of laser beams. The patterned azobenzene functionalized film is then etched in the plasma chamber such that the gratings are transferred to the PET substrate. Finally, any remaining azobenzene functionalized polymer is dissolved away using an appropriate solvent. This method of patterning can be broadly applied to a variety of flexible/polymeric substrates and the resolution is not limited by the substrate thermo-mechanical properties. 相似文献
992.
993.
Fabrication of gold nano‐patterns has been demonstrated employing surface relief structures created on films of an azobenzene‐functionalized polymer as templates. The surface relief templates were photoinscribed on the azopolymer films in one‐step with two laser beams. Thin layers of gold were over‐coated on the polymer templates by thermal evaporation. Gold lines of a few hundred nanometer width were successfully fabricated by pyrolyzing the azobenzene polymer. Sub‐micron gold dots were also created. The resulting gold structures exhibited the same periodicity as the polymer templates. 相似文献
994.
A series of fluorine‐containing diblock copolymers based on lauryl methacrylate and 1H,1H,2H,2H‐perfluoroalkyl acrylate have been prepared by atom transfer radical polymerization (ATRP). The preparation process of PLMA‐Br macroinitiators was controlled within a reasonable time corresponding to the ln [M0]/[Mt]~time plot of the reaction. FTIR, 1H‐NMR, GPC and fluorine‐element analysis (FEA) were used to characterize the synthesized block copolymers. The solid surface activity of these polymers was demonstrated by contact angle measurement. The polymer films prepared by block copolymers with more than three fluorinated units showed low dispersion force contributions to the surface energy indicating the presence of the fluorinated block at the surface. The surface activity in solutions was measured by drop‐weight method. Ii is interesting to find, when the fluorine weight percentage is controlled constant, that PLMA‐b‐PFAEA with larger molecular size is more prominent in exploiting the fluorinated structure to reduce the surface tension of solutions. The block copolymer's ability in reducing surface tension of solutions also depends on the type of solvent. 相似文献
995.
In this study for preparing the better performance scaffold materials for peripheral nerve repairing, the collagen‐based composite scaffolds are crosslinked with glutaraldehyde and their structure and performance are investigated. The results of FTIR indicated that the collagen and chitosan are certainly crosslinked through GTA without any significant change in the chemical property. It was observed under a scanning electron microscope (SEM) that the crosslinked collagen‐based composite scaffolds had a porous three‐dimensional cross‐linked structure. The experiments showed that the biostability of the scaffold is greatly enhanced, but the GTA crosslinking induces the potential cytotoxicity and poor hydrophilic nature. To overcome these disadvantages, the low temperature plasma technology is utilized to modify the surface of the cross‐linked collagen‐based composite scaffolds in this study. Measurements of water contact angle showed that hydrophilic nature of surface of the scaffolds was improved after low temperature plasma technology modification. The cell proliferation experiments revealed that the modified collagen‐based composite scaffolds still kept their bioactivity and benefited the proliferation. 相似文献
996.
Abstract We report a molecular dynamics study on the 1:1 M3+ lanthanide (La3+, Eu3+ and Yb3+) inclusion complexes of an important extractant molecule L: a calix[4]arene-tetraalkyl ether substituted at the wide rim by four NH-C(O)-CH2-P(O)Ph2 arms. The M(NO3)3 and MCl3 complexes of L are compared in methanol solution and at a water / chloroform interface. In the different environments the coordination sphere of M3+ involves the four phosphoryl oxygens and three to four loosely bound carbonyl oxygens of the CMPO-like arms. Based on free energy simulations, we address the question of ion binding selectivity in pure liquid phases and at the liquid-liquid interface where L and the complexes are found to adsorb. According to the simulations, the enhancement of M3+ cation extraction in the presence of the calixarene platform, examined by comparing L to the (CMPO)4 “ligand” at the interface, is related to the fact that (i) the (CMPO)4Eu(NO3)3 complex is more hydrophilic than the LEu(NO3) one and (ii) the free CMPO ligands spread at the interface, and are therefore less organized for cation capture than L. 相似文献
997.
998.
The signatures of nanosolvation on the one‐ and two‐dimensional (1D and 2D) IR spectra of a proton‐transfer mode in a hydrogen‐bonded complex dissolved in polar solvent molecule nanoclusters of varying size are elucidated by using mixed quantum–classical molecular dynamics simulations. For this particular system, increasing the number of solvent molecules successively from N=7 to N=9 initiates the transition of the system from a cluster state to a bulk‐like state. Both the 1D and 2D IR spectra reflect this transition through pronounced changes in their peak intensities and numbers, but the time‐resolved 2D IR spectra also manifest spectral features that uniquely identify the onset of the cluster‐to‐bulk transition. In particular, it is observed that in the 1D IR spectra, the relative intensities of the peaks change such that the number of peaks decreases from three to two as the size of the cluster increases from N=7 to N=9. In the 2D IR spectra, off‐diagonal peaks are observed in the N=7 and N=8 cases at zero waiting time, but not in the N=9 case. It is known that there are no off‐diagonal peaks in the 2D IR spectrum of the bulk version of this system at zero waiting time, so the disappearance of these peaks is a unique signature of the onset of bulk‐like behavior. Through an examination of the trajectories of various properties of the complex and solvent, it is possible to relate the emergence of these off‐diagonal peaks to an interplay between the vibrations of the complex and the solvent polarization dynamics. 相似文献
999.
Applications of graphene sheets in the fields of biosensors and biomedical devices are limited by their insolubility in water. Consequently, understanding the dispersion mechanism of graphene in water and exploring an effective way to prepare stable dispersions of graphene sheets in water is of vital importance for their application in biomaterials, biosensors, biomedical devices, and drug delivery. Herein, a method for stable dispersion of graphene sheets in water by single‐stranded oligodeoxynucleotides (ssODNs) is studied. Owing to van der Waals interactions between graphene sheets, they undergo layer‐to‐layer (LtL) aggregation in water. Molecular dynamics simulations show that, by disrupting van der Waals interaction of graphene sheets with ssODNs, LtL aggregation of graphene sheets is prevented, and water molecules can be distributed stably between graphene sheets. Thus, graphene sheets are dispersed stably in water in the presence of ssODNs. The effects of size and molarity of ssODNs and noncovalent modification of graphene sheets are also discussed. 相似文献
1000.
Thomas Waldmann Jens Klein Prof. Dr. Harry E. Hoster Prof. Dr. R. Jürgen Behm 《Chemphyschem》2013,14(1):162-169
Investigating the dynamics in an adlayer of the oligopyridine derivative 2‐phenyl‐4,6‐bis(6‐(pyridine‐2‐yl)‐4‐(pyridine‐4‐yl)pyridine‐2‐yl)pyrimidine (2,4′‐BTP) on Ag(111) by fast scanning tunneling microscopy (video‐STM), we found that rotating 2,4′‐BTP adsorbates coexist in a two‐dimensional (2D) liquid phase (β‐phase) in a dynamic equilibrium with static adsorbate molecules. Furthermore, exchange between an ordered phase (α‐phase) and β‐phase leads to fluctuations of the domain boundary on a time scale of seconds. Quantitative evaluation of the temperature‐dependent equilibrium between rotating and static adsorbates, evaluated from a large number of STM images, gains insight into energetic and entropic stabilization and underlines that the rotating adsorbate molecules are stabilized by an entropy contribution, which is compatible with that derived by using statistical mechanics. The general validity of the concept of entropic stabilization of rotating admolecules, favoring rotation already at room temperature, is tested for other typical small, mid‐size and large adsorbates. 相似文献