Functionalization of different polymers with sulfonic groups as a way to coat them with a biomimetic apatite layer

Covalent coupling of sulfonic group (–SO₃H) was attempted on different polymers to evaluate efficacy of this functional group in inducing nucleation of apatite in body environment, and thereupon to design a simple biomimetic process for preparing bonelike apatite-polymer composites. Substrates of polyethylene terephthalate (PET), polycaprolactam (Nylon 6), high molecular weight polyethylene (HMWPE) and ethylene-vinyl alcohol co-polymer (EVOH) were subjected to sulfonation by being soaked in sulfuric acid (H₂SO₄) or chlorosulfonic acid (ClSO₃H) with different concentrations. In order to incorporate calcium ions, the sulfonated substrates were soaked in saturated solution of calcium hydroxide (Ca(OH)₂). The treated substrates were soaked in a simulated body fluid (SBF). Fourier transformed infrared spectroscopy, thin-film X-ray diffraction, and scanning electron microscopy showed that the sulfonation and subsequent Ca(OH)₂ treatments allowed formation of –SO₃H groups binding Ca²⁺ ions on the surface of HMWPE and EVOH, but not on PET and Nylon 6. The HMWPE and EVOH could thus form bonelike apatite layer on their surfaces in SBF within 7 d. These results indicate that the –SO₃H groups are effective for inducing apatite nucleation, and thereby that surface sulfonation of polymers are effective pre-treatment method for preparing biomimetic apatite on their surfaces.     

Photoinduced spontaneous and stimulated emission in sexithiophene single crystals

Temperature dependent steady-state and transient photoluminescence (PL) measurements were carried out on sexithiophene (6T) single crystals. As the temperature is lowered, three different sets of equally spaced peaks appear on the steady state PL spectrum. This behavior is interpreted in the frame of the molecular exciton theory. The first energy set is attributed to transitions to the lower level of the Davydov splitting of the 1B_u excited state of the isolated molecule, whereas the two other sets are ascribed to the crystal defects. An analysis of the PL emission and excitation spectra allowed us to establish a general exciton energy scheme of sexithiophene crystal. At low excitation levels, the transient PL follows a single exponential decay, with a decay time of 1.8 ± 01 ns. When the excitation energy is increased, a second, much faster component is added. Concurrently, the PL spectrum narrows to a single line centered at the origin of the low energy set of the steady state PL. The width of the emission line is 13 cm⁻¹ at 10 K, and tends to widen and shift towards lower energies when the temperature is raised. All these observations are accounted for in term of stimulated emission.     

Functionalization of BN nanotubes with dichlorocarbenes

The geometric and electronic structures of dichlorocarbene (CCl(2)) functionalized BN nanotubes (BNNTs) were studied using density functional theory within the generalized gradient approximation. We found that the CCl(2) addition favors slanted B-N bonds in zigzag tubes, and the CCl(2)-attached BNNTs prefer open rather than closed three-membered-ring (3MR) structures in all the zigzag (n,0) BNNTs studied, whereas closed 3MR structure occurs in the CCl(2)-attached BN graphene layer. The binding energies decrease with increase of the CCl(2) coverage, but the electronic properties of BNNTs do not change significantly, irrespective of the CCl(2) coverage.     

Functionalization of textile materials with silver nanoparticles

Nanoparticles gained much scientific attention in the past decade due to their specific surface chemistry and properties which are significantly different from that of the corresponding bulk materials. Silver nanoparticles were the most extensively studied and they can be already found in a wide range of commercially available products. This article reviews the latest developments in finishing of textile materials with differently synthesized silver nanoparticles. Although antimicrobial activity of functionalized textile materials was primarily discussed, the possibilities to apply silver nanoparticles as a colorant or antistatic agent were also evaluated. In addition, the effect of chemical and physico-chemical activation of fibers before loading of silver nanoparticles on their binding efficiency was considered. Taking into account the importance of environmental impact of novel technologies, potential environmental risks emerging from silver release during washing of textile materials have been also discussed.     

Functionalization of silicon nanowire surfaces with metal-organic frameworks

Metal-organic frameworks (MOFs) and silicon nanowires (SiNWs) have been extensively studied due to their unique properties; MOFs have high porosity and specific surface area with well-defined nanoporous structure, while SiNWs have valuable one-dimensional electronic properties. Integration of the two materials into one composite could synergistically combine the advantages of both materials and lead to new applications. We report the first example of a MOF synthesized on surface-modified SiNWs. The synthesis of polycrystalline MOF-199 (also known as HKUST-1) on SiNWs was performed at room temperature using a step-by-step (SBS) approach, and X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and energy dispersive spectroscopy elemental mapping were used to characterize the material. Matching of the SiNW surface functional groups with the MOF organic linker coordinating groups was found to be critical for the growth. Additionally, the MOF morphology can by tuned by changing the soaking time, synthesis temperature and precursor solution concentration. This SiNW/MOF hybrid structure opens new avenues for rational design of materials with novel functionalities.      

桥位芳香性给电子基团取代的苝二酰亚胺的合成及其光伏性能

采用Suzuki反应合成出了系列桥位芳香性给电子基团(三苯胺与N-苯基咔唑基团)取代的苝二酰亚胺衍生物2a～2d,并对其光学及电化学性能进行了表征。结果发现桥位经过芳香性给电子基团取代后,苝二酰亚胺的吸收范围拓宽,吸收峰发生红移;同时,其前线轨道能级上升,具有给电子能力。由此,制备了以2a～2d为电子给体的有机太阳能电池,电池具有明显的光伏响应。     

In situ charge-modulation spectroscopy of oligothiophene field-effect diodes: from sexithiophene towards polythiophene

We have studied the charged excitations in a series of oligothiophenes of increasing conjugation length, namely -6T, -8T and substituted -12T, in order to gain insight into how charge is stored in polythiophenes and to investigate how the polaron and bipolaron concepts relate to molecular cations and dications. We measured optical charge-modulation spectra of thin solid films of oligomers within field-effect diodes, because of the direct relevance to organic thin-film transistors and also the ability to induce unipolar charge carriers by purely electrostatic means, without introducing chemical dopants. By modulating the gate voltage and probing the resulting modulation of optical absorption at the same frequency, we have observed optical transitions characteristic of the charged excitations of these oligomers in the solid state.     

Functionalization of Porous Carbon Materials with Designed Pore Architecture

Recent progress in syntheses of porous carbons with designed pore architecture has rejuvenated the field of carbon chemistry and promises to provide new advanced materials. In order to reap the full benefit of designer carbons, it is necessary to develop chemistries for functionalizing the porous carbon surfaces. This Review examines methods of functionalizing porous carbon through direct incorporation of heteroatoms in the carbon synthesis, surface oxidation and activation, halogenation, sulfonation, grafting, attachment of nanoparticles and surface coating with polymers. Methods of characterizing the functionalized carbon materials and applications that benefit from functionalized nanoporous carbons with designed architecture are also highlighted.     

Functionalization of gold-coated carbon nanotubes with self-assembled monolayers of thiolates

Multi-walled carbon nanotubes (CNT) were synthesized by chemical vapor deposition using Co–Fe as a catalyst and ethylene as a carbon source. Afterward, a simple method combining wet-chemistry and chemical reduction was used to prepare carbon nanotube/gold material (CNT/Au). Pristine nanotubes and CNT/Au were characterized by transmission electron microscopy micrographs. It appeared that gold formed nanoparticles on CNTs endings and their sidewalls. Further functionalization was carried out by using thiols of different chemical properties and molecule sizes. Thiols formed self-assembled monolayer on gold surface that led to formation of CNT/gold/thiol-functionalized material. The amounts of chemisorbed thiols were measured by elemental analysis and thermogravimetry.     

Functionalization of hydroxyl terminated polybutadiene with biologically active fluorescent molecule

A biologically active molecule, 2-chloro-4,6-bis(dimethylamino)-1,3,5-triazine (CBDT), has been covalently attached at the terminal carbon atoms of the hydroxyl terminated polybutadiene (HTPB) backbone. The modification of HTPB backbone by CBDT molecule does not affect the unique physico-chemical properties such as fluidity, hydroxyl value and microstructure of the parent HTPB. The formation of hydrogen bonding between the terminal hydroxyl groups and the nitrogen atoms of triazine moiety is the driving force for the terminal attachment chemistry. The functionalized HTPB (HTPB-CBDT) shows a strong fluorescence emission at 385 nm.     

Functionalization of low-dimensional honeycomb germanium with 3d transition-metal atoms

The energetics, electronic and magnetic properties of 3d transition-metal (TM) atoms adsorbed low-dimensional Ge honeycomb structures have been systematically investigated from the spin-polarized density-functional theory calculations. For the two-dimensional Ge honeycomb structure, all TM atoms considered prefer to adsorb on the hollow site of the buckled hexagon in both single-sided and double-sided adsorption cases, with binding energies ranging between 3.27 and 5.92 eV. Upon adsorption, the semimetallic 2D honeycomb Ge can change to either ferromagnetic or antiferromagnetic metals depending on both TM species and coverage density. For the one-dimensional structure, we found binding of TM atoms to hollow site of the edge hexagon yields the minimum energy state for all TM species considered and in all three AGeNRs examined which belong to different families. Depending on ribbon width, adsorbed TM species and adsorption concentration, most of the TM decorated AGeNRs can either be metals or semiconductors with ferromagnetic or antiferromagnetic spin alignment, except for Co-adsorbed ones which remain to be nonmagnetic. Interestingly, Cr or Mn adsorption can make certain AGeNRs to be half-metallic with a 100% spin-polarization at Fermi level which can be good candidates for future application in spintronic fields. Furthermore, the effect of the on-site Coulomb interaction on the stability of these half-metallic ribbons is also considered by performing L(S)DA + U calculations, and the results show that the half-metallic ground state of the Cr-adsorbed ribbons is more robust than that of the Mn-adsorbed one.     

Functionalization of biodegradable magnesium alloy implants with alkylphosphonate self-assembled films

Mg and Mg-alloys are promising materials for biodegradable implants. In order to slowdown the Mg-alloy (AZ91D) degradation and enhance its biocompatibility, the alloy surface was modified with alkylphosphonate self-assembling films. The binding configuration and the structural organization of alkylphosphonate monolayers on the Mg-alloy surface were investigated using contact angle measurements, FTIR, and XPS. Combination of FTIR and XPS data indicated the presence of several different bonding modes (mono-, di-, and tri dentate) of phosphonate head groups with the alloy surface. The existence of well organized and ordered self-assembled alkylphosphonate monolayers with good barrier protecting properties in a physiological solution is a key step in the development of biocompatible Mg-alloy implants.     

碳基光热转换纳米材料的表面功能化和生物应用

光热治疗技术已经引起了广泛的重视,其走向应用的前提是开发出高效稳定的光热转换材料.碳基光热转换纳米材料具有毒性小、稳定性高等优点,已经成为了研究的热点.综述了碳基光热转换纳米材料(包括纳米碳管和石墨烯)的研究进展,重点论述了其表面改性技术(包括非共价键改性和共价键改性方法);随后总结了其表面功能化方法,主要有RGD、抗体、叶酸和DNA等靶向性功能化的修饰方法;最后介绍了其在光热治疗、近红外热成像等生物医药方面的应用.