Amine-rich Surface Research Articles

Elucidating the Synergistic Promotional Mechanism of Water and Oxygen in the Aerobic C-C Homocoupling Reaction Catalyzed by Visible-Light-Derived Core-Shell Pd@A-CQDs Nanostructures.

Rational design and precise synthesis of biogenic noble-metal-based catalysts possessing distinctive structure and composition play a crucial role in the chemical industry, enabling sustainable construction of an inclusive range of chemical resources. In this study, we have effectively fabricated Pd@A-CQDs through a straightforward one-pot aqueous protocol assisted by visible light employing renewable biomass-derived amine-rich carbon quantum dots (A-CQDs). The remarkable visible light harnessing capability (bandgap, ca. 2.81 eV), high density (35.7 × 1018 cm-3), and long lifetime (25 ps) of photocharge carriers and amine-rich surface in A-CQDs make them ideal candidates as both reducing and stabilizing agents, thereby facilitating the in situ construction of metallic Pd(0) nanoparticles. Comprehensive physicochemical characterizations have provided compelling evidence for the spherical morphology of Pd@A-CQDs core-shell nanostructures, with ultrathin A-CQDs shells of ca. 1.9 nm and an average diameter of 14 ± 1 nm. The effectiveness of the synthesized Pd@A-CQDs catalysts was assessed in the ligand- and base-free homocoupling reaction of arylboronic acids in water at ambient temperature. The catalytic tests demonstrated the selective production of the homocoupled compound over protodeboronation products with excellent yield and high catalyst recyclability under ambient conditions. The protocol employed exhibited a high TOF (1.05 × 10-2 mol g-1 min-1) and a low E-factor, with a remarkably low palladium loading. XPS analysis confirmed the retention of the metallic nature of the palladium core within the catalysts during the reaction. The catalytic function of the palladium core in conjunction with the A-CQDs shell, along with the promotional effects provided by water and oxygen for the formation of nucleophilic tetravalent boron, was conclusively recognized by 11B NMR and O2-TPD measurements. The obtained experimental results deliver valuable insights into the probable reaction pathway for the homocoupling reaction catalyzed by the Pd@A-CQDs catalysts. Through a comprehensive and sustainable evaluation, the current methodology exhibits superior performance compared to previously documented techniques in relation to estimated circularity and adherence to good manufacturing practices (GMP).

Iodine functionalized 2,5-dimethoxy-2,5-dihydrofuran (DHFI) crosslinked whey protein-derived carbon nanodots (WCND) for antibacterial application

Whey protein-derived carbon nanodots (WCND) were synthesized using the microwave irradiation method, and its amine-rich surface functionality was crosslinked with covalently bound Iodine functionalized 2,5-dimethoxy-2,5-dihydrofuran (DHFI) to produce WCND-DHFI. The physicochemical characterization of both WCND and WCND-DHFI was performed and compared to comprehend the consequence of iodination on the characteristics of WCND. The suitability of CND in biological environments was evaluated through in vitro cytocompatibility and Chorioallantoic Membrane (CAM) assay, as well as a hemocompatibility study. WCND-DHFI has shown enhanced cell viability against WCND. Further, the antibacterial properties of both CNDs were studied against both gram-positive and gram-negative bacterial strains, representing an enhancement in antibacterial activity after DHFI crosslinking. WCND-DHFI has depicted a stable and prominent bacteriostatic activity for up to 6 h for both strains of bacteria. WCND-DHFI has denoted a 99.996% and 99.999% loss of bacterial viability for gram-positive and negative strains, respectively. Novel surface functionalization portrays an improvement in antibacterial activity. Transmission and scanning electron microscopy represent the cell wall rupturing by the WCND-DHFI, resulting in bacterial death. The ROS-mediated bacteriostatic mechanism of WCND-DHFI has been explored through assessing lipid peroxidation and protein oxidation assay. Moreover, the oxidative damage of DNA also has been explored. WCND-DHFI is performing as a promising cytocompatible and hemocompatible material for antibacterial applications.

MOF-derived CoNC@rGO/amine-rich@rGO/fluorinated-epoxy nanocomposites with EMI shielding, mechanical robustness, superamphiphobicity and long-term anticorrosion properties

Along with the rapid development of electronic devices and communication systems, electromagnetic (EM) radiation pollution has become an increasingly serious problem. However, it is greatly challenging to achieve absorption-dominated electromagnetic interference (EMI) shielding and robust multifunctional simultaneously. In this work, we synthesize zeolitic imidazolate framework (ZIF67)-derived CoNC@reduced graphene oxide (rGO) and amine-rich surface rGO (NH2@rGO), and subsequently fabricate NH2-CoNC@rGO-fluorinated epoxy (FEP) nanocomposites by the microwave irradiation strategy, and this is the first time to obtain composite combining excellent EMI shielding, mechanical robustness, superamphiphobicity and long-term anticorrosion properties. Wherein, 3-(perfluoro-n-octyl) propenoxide (PFOP) provides the perfluorinated long chains, which improves both mechanical properties via internal antiplasticization effect, and the dispersity and loading of nanofiller via CF⋯HN/π interactions; 4,4′-hexafluoroisopropylidenediphenol diglycidyl ether (FAEP) increases the compatibility and mechanical robustness; NH2@rGO provides the good interfacial bonding, dielectric attenuation and anode protection; CoNC@rGO endows suitable magnetic and dipolar relaxation loss, micro/nanostructures and cathodic protection. Remarkably, the optimized nanocomposite exhibits satisfied tensile and impact strength (64.4 MPa, 33.7 kJ/m2), EMI shielding properties (56 dB), thermal conductivity (1.13 W·m−1·K−1), superhydrophobicity (154°) and superoleophobicity (151°), self-cleaning, good chemical and mechanical robustness, Joule heating capacity and long-term anticorrosion (30 d). Furthermore, the microwave irradiation effect, multiple EMI shielding and anti-corrosion mechanism have been discussed in detail. This study provides an efficient guideline for designing multicomponent and multidimensional epoxy nanocomposite with EMI shielding and robust multifunctional property in aerospace, underwater equipment, electronic devices and precision construction protection.

Cage-like amine-rich polymeric capsule with internal 3D center-radial channels for efficient and selective gold recovery

With the ever-increasing demand for electronics, recovering precious metals from secondary sources such as electronic waste is both environmentally and economically attractive. However, a challenge still remains in how to realize the highly selective and efficient recovery of a particular metal of interest. Here, a novel cage-like amine-rich polymeric capsule (APC) with internal 3D center-radial pore channels was prepared through a solvent-exchange method to efficiently separate gold from secondary sources. A thin shell of APC allows the gold ions to penetrate well into the APC inside, and the amine-rich surface in the interior hierarchical pore structure selectively reduces the gold ions to nanocrystals in the presence of interference ions (recovery selection ratio of Au/Cu = 9,103, Au/Ni = 15,172, and Au/Zn = 3,240). Moreover, the thin shell of APC enhances recovery stability by preventing the release of the gold nanocrystals to the exterior, and also by preventing clogging of the internal 3D center-radial pore channels in the presence of various suspended solids such as metallic, hydrophobic, and hydrophilic nanoparticles that may exist as impurities in the gold recovery process. Consequently, the APC adsorbent achieved a gold recovery ratio of ∼ 99%, maintained even after 10 cycles of repetitive adsorption/desorption. Thus, the APC offers a pragmatic way possible to address intrinsic drawbacks of conventional nano- and micro-sized adsorbents such as low recovery stability after use, selectivity for gold ion, and low tractability.

Comparison of conjugating chondroitin sulfate A and B on amine-rich surface: For deeper understanding on directing cardiovascular cells fate

Chondroitin sulfate (CS) is often used as an ideal drug for long-term prevention of cardiovascular diseases with the advantages of anti-inflammation and promoting blood circulation. In the previous work, the natural CS was conjugated onto the amine rich surface to enhance the biocompatibility of cardiovascular stents . In this study, we choose an artificial CS subtype, CS B, as the functional molecule to prepare a functionalized surface on the poly-dopamine (PDA)/hexanediamine (HD) co-deposited stent to direct the cardiovascular cells fate in comparison with the coating prepared with the natural CS subtype, CS A. Although the PDA/HD-CS B coating exhibited no advantage of inhibiting platelet adhesion compared to PDA/HD-CS A coating, it showed stronger functions on inhibiting adhesion of whole blood composition, further reducing the thrombosis, and contributing broader lumen patency and more blood flow. In addition, PDA/HD-CS B was endowed better ability on directing the fate of vascular cells, i.e. smooth muscle cells (SMC), macrophages, endothelial cells (EC) and endothelial progenitor cells (EPC). Surprisingly, as the main natural subtype of CS, CS A didn't contribute to the formation of endothelial monolayer within 30 days like CS, while the conjugated CS B obtained a complete endothelial monolayer benefiting from its stronger function on regulating the cardiovascular cells behaviors in time sequence and space sequence.

Sequential Ammonia and Carbon Dioxide Adsorption on Pyrolyzed Biomass to Recover Waste Stream Nutrients.

The amine-rich surfaces of pyrolyzed human solid waste (py-HSW) can be “primed” or “regenerated” with carbon dioxide (CO2) to enhance their adsorption of ammonia (NH3) for use as a soil amendment. To better understand the mechanism by which CO2 exposure facilitates NH3 adsorption to py-HSW, we artificially enriched a model sorbent, pyrolyzed, oxidized wood (py-ox wood) with amine functional groups through exposure to NH3. We then exposed these N-enriched materials to CO2 and then resorbed NH3. The high heat of CO2 adsorption (Qst) on py-HSW, 49 kJ mol–1, at low surface coverage, 0.4 mmol CO2 g–1, showed that the naturally occurring N compounds in py-HSW have a high affinity for CO2. The Qst of CO2 on py-ox wood also increased after exposure to NH3, reaching 50 kJ mol–1 at 0.7 mmol CO2 g–1, demonstrating that the incorporation of N-rich functional groups by NH3 adsorption is favorable for CO2 uptake. Adsorption kinetics of py-ox wood revealed continued, albeit diminishing NH3 uptake after each CO2 treatment, averaging 5.9 mmol NH3 g–1 for the first NH3 exposure event and 3.5 and 2.9 mmol NH3 g–1 for the second and third; the electrophilic character of CO2 serves as a Lewis acid, enhancing surface affinity for NH3 uptake. Furthermore, penetration of 15NH3 and 13CO2 measured by NanoSIMS reached over 7 μm deep into both materials, explaining the large NH3 capture. We expected similar NH3 uptake in py-HSW sorbed with CO2 and py-ox wood because both materials, py-HSW and py-ox wood sorbed with NH3, had similar N contents and similarly high CO2 uptake. Yet NH3 sorption in py-HSW was unexpectedly low, apparently from potassium (K) bicarbonate precipitation, reducing interactions between NH3 and sorbed CO2; 2-fold greater surface K in py-HSW was detected after exposure to CO2 and NH3 than before gas exposure. We show that amine-rich pyrolyzed waste materials have high CO2 affinity, which facilitates NH3 uptake. However, high ash contents as found in py-HSW hinder this mechanism.

Biocompatibility of Cyclopropylamine-Based Plasma Polymers Deposited at Sub-Atmospheric Pressure on Poly (ε-caprolactone) Nanofiber Meshes

In this work, cyclopropylamine (CPA) monomer was plasma-polymerized on poly (ε-caprolactone) nanofiber meshes using various deposition durations to obtain amine-rich surfaces in an effort to improve the cellular response of the meshes. Scanning electron microscopy and X-ray photoelectron spectroscopy (XPS) were used to investigate the surface morphology and surface chemical composition of the PCL samples, respectively. The measured coating thickness was found to linearly increase with deposition duration at a deposition rate of 0.465 nm/s. XPS analysis revealed that plasma exposure time had a considerable effect on the surface N/C and O/C ratio as well as on amino grafting efficiency and amino selectivity. In addition, cell studies showed that cell adhesion and proliferation significantly improved for all coated samples.

One-step synthesis of amine-functionalized fluorescent silicon nanoparticles for copper(II) ion detection

Amine-functionalized silicon nanoparticles (A-SiNPs) with intense green fluorescence and photostability are synthesized via a one-step, low-cost hydrothermal method under mild conditions using 3-aminopropyl triethoxysilane (APTES) as a silicon source and L-ascorbic acid (AA) as a reducing reagent. The amine-rich surface not only improves water dispersability and stability of the A-SiNPs but also offers a specificcopper(II) ion (Cu2+) coordination capability. The as-prepared A-SiNPs can be directly employed forCu2+ detection in "turn-off" mode, resulting from Cu2+ coordination-induced fluorescence quenching effect. Under optimal conditions, Cu2+ detection was accomplished with a linear range from 1 to 500μM and a limit of detection (LOD) at 0.1μM, which was much lower than the maximum level (~ 20μM) of Cu2+ in drinking water permitted by the US Environmental Protection Agency (EPA). In addition, the A-SiNPs were successfully used to detect Cu2+ in spiked river water, demonstrating its good selectivity and potential application for analysis of surface water samples. Graphical abstract.

Synthesis of Negatively Charged Polyol-Functional PSF Membranes with Good Hydrophilic and Efficient Boron Removal Properties.

Boron removal remains a major barrier to water purification, it is important to develop a specialized adsorption membrane for boron removal. By means of a simple and effective method, a hydrophilic membrane for boron removal with a polyhydroxy functional group on the surface was prepared. Firstly, a polysulfone (PSF) membrane was modified by co-depositing polyethyleneimine (PEI) with dopamine (DA) in one-step to produce amine-rich surfaces, then the DA/PEI-functionalized membranes were reacted with glycidol, with the prepared membranes corresponding to PSF-PDA/PEI membranes and PSF-diol membranes. The prepared membranes were characterized by water-uptake, FTIR, (X-ray photoelectron spectroscopy) XPS, (Field emission scanning electron microscope) FESEM, and zeta potential measurements. The hydrophilicity of the membrane was characterized by the static water contact angle (WCA) test. In addition, we systematically studied the impact of initial boron concentration, chelating time, and pH value on boron removal performance. The results showed that the PSF-diol membrane had strong hydrophilicity with a WCA of about 38°. The maximum adsorption capacity of boron appeared to be 1.61 mmol/g within 10 min at a boron concentration of 300 mg/L. Adsorption kinetics showed that saturation adsorption can be achieved in minutes at the initial concentration of 5 mg/L, which is beneficial to a rapid filtration process.

Achieving high-performance epoxy nanocomposites with trifunctional poly(oxypropylene)amines functionalized graphene oxide

In this article, two types of functional graphene oxide (GO) with amine-rich surface were synthesized through chemically grafting two different molecular chain length trifunctional poly(oxypropylene)amines T5000 and T403, which were named as T5000-GO and T403-GO, respectively. The functionalized GO was then added to epoxy (EP) resin. Fourier transform infrared spectra analysis confirmed successful chemical functionalization on GO. Both T403-GO and T5000-GO were tightly embedded in the EP, because the amine-rich surface of functionalized-GO could form covalent bonds with the EP matrix, thereby contributing to the enhancement of mechanical properties. Particularly, T5000-GO, which has longer grafting molecule chains, achieved better compatibility and dispersibility in the EP matrix, resulting in a better reinforcing efficiency in mechanical properties. For example, the T5000-GO/EP composites showed an incremental enhancement in tensile strength with increasing filler concentrations, whereas their T403-GO/EP counterparts failed to follow the same trend. Meanwhile, the T5000-GO/EP composites with only 0.1-wt% T5000-GO achieved a prominent increase in flexural strength (approximately 50%) and flexural modulus (approximately 26.8%), which were higher than those of T403-GO-filled counterparts. This work indicated that the compatibility and interphase between GO and EP could be designed by manipulating the length of grafting molecule chains, thereby providing a better understanding of the relationship between the structure and mechanical properties of the graphene/EP nanocomposites.

Controlling Molecular Weight of Hyaluronic Acid Conjugated on Amine-rich Surface: Toward Better Multifunctional Biomaterials for Cardiovascular Implants.

The molecular weights (MWs) of hyaluronic acid (HA) in extracellular matrix secreted from both vascular endothelial cells (VECs) and vascular smooth muscle cells (VSMCs) play crucial roles in the cardiovascular physiology, as HA with appropriate MW influences important pathways of cardiovascular homeostasis, inhibits VSMC synthetic phenotype change and proliferation, inhibits platelet activation and aggregation, promotes endothelial monolayer repair and functionalization, and prevents inflammation and atherosclerosis. In this study, HA samples with gradients of MW (4 × 103, 1 × 105, and 5 × 105 Da) were prepared by covalent conjugation to a copolymerized film of polydopamine and hexamethylendiamine (PDA/HD) as multifunctional coatings (PDA/HD-HA) with potential to improve the biocompatibility of cardiovascular biomaterials. The coatings immobilized with high-MW-HA (PDA/HD-HA-2: 1 × 105 Da; PDA/HD-HA-3: 5 × 105 Da) exhibited a remarkable suppression of platelet activation/aggregation and thrombosis under 15 dyn/cm2 blood flow and simultaneously suppressed the adhesion and proliferation of VSMC and the adhesion, activation, and inflammatory cytokine release of macrophages. In particular, PDA/HD-HA-2 significantly enhanced VEC adhesion, proliferation, migration, and functional factors release, as well as the captured number of endothelial progenitor cells under dynamic condition. The in vivo results indicated that the multifunctional surface (PDA/HD-HA-2) created a favorable microenvironment of endothelial monolayer formation and functionalization for promoting reendothelialization and reducing restenosis of cardiovascular biomaterials.

Strong multi-functions based on conjugating chondroitin sulfate onto an amine-rich surface will direct the vascular cell fate for cardiovascular implanted devices.

Thrombus, hyperplasia, and inflammation are constant threats and challenges for long-term application of cardiovascular implants. Surface endothelialization has been considered as the preferable strategy to solve these problems because of the physiological functions gained from the regenerated endothelial layers covering the implants. Thus, a surface with strong multi-functions including anti-coagulation, anti-hyperplasia, anti-inflammation, and pro-endothelialization is ideal for cardiovascular implants. Herein, we developed a novel coating by conjugating chondroitin sulfate (CS) onto an amine-rich copolymerized film of polydopamine (PDA) and hexamethylenediamine (HD), with the aim of directing the vascular cell fate. The PDA/HD-CS coating exhibited a remarkable suppression of platelet activation/aggregation and thrombosis under a blood flow of 15 dyn cm-2. Inhibition upon proliferation of vascular smooth muscle cells and attachment of macrophages were also observed on this coating. In addition, the PDA/HD-CS coating was compatible with the vascular endothelial cells, suggesting a strong pro-endothelialized function. Further in vivo tests indicated that contractile smooth muscle cells and M2 macrophages regulated by PDA/HD-CS may be involved in the regeneration of the endothelial layer. In summary, this research may support potential applications for surface modification of cardiovascular implants to achieve improved multi-functions.

Dopamine-assisted deposition of poly (ethylene imine) for efficient heparinization

Mussel-inspired self-polymerization of dopamine in the presence of catechols and amines can be used to form coatings on various substrates. In this work dopamine was co-polymerized with poly (ethylene imine) (PEI) to form coatings on 316L stainless steel (SS). The coating formation was confirmed by Fourier transform infrared spectra (FTIR) and X-ray photoelectron spectroscopy (XPS). Compared with a pure polydopamine coating, such hybrid coating presented a higher ratio of nitrogen and increased zeta potential due to the introduction of PEI components. QCM measurement showed good affinity for heparin immobilization on the amine-rich surfaces. Moreover, the heparin-binding surface significantly suppressed platelet adhesion and activation. Further, the interaction with vascular cells, like endothelial cells (ECs) and smooth muscle cells (SMCs) was also investigated. The heparin coating not only decreased the cytotoxicity of amines on ECs, but also significantly inhibited SMCs proliferation. These results showed that the hybrid coating allowed effective heparin immobilization, providing a promising platform for vascular devices modification.

Development of water stable N-rich butadiene based plasma polymer films for endovascular coiling

Event Abstract Back to Event Development of water stable N-rich butadiene based plasma polymer films for endovascular coiling Madhuwanthi Buddhadasa1, Sophie Lerouge2 and Pierre-Luc Girard-Lauriault1 1 McGill University, Plasma Processing Laboratory, Department of Chemical Engineering, Canada 2 ÉTS, Laboratory of Endovascular Biomaterials, CHUM research Centre & Department of Mechanical Engineering, Canada Introduction: Endovascular coiling is the minimally invasive treatment for brain aneurysms. It involves inserting a coil into the aneurysm through a microcatheter, promoting blood coagulation around the coil and inside the aneurysm in order to help healing, exclude aneurysm from blood flow and prevent it from rupture. Stimulating coagulation is therefore a key feature of endovascular coils, which limits the use of synthetic polymers owing to their ineffective biological-reactivity. Both platelet adhesion and activation of the coagulation cascade are mediated by adsorbed plasma proteins, which are well known to depend on biomaterials surface properties. On account of their highly tunable surface properties and easy adhesion to almost any substrate, plasma polymer (PP) films are potential candidates to promote blood coagulation. Primary amine-rich PP coatings were shown to promote fibrinogen (Fg) adsorption and platelet adhesion and activation[1]. In this project, we propose to use 1,3-butadiene based PP films, stable in aqueous media and rich in amine groups, to promote protein adsorption, platelet activation and coagulation around polymeric coils. Materials and Methods: PP films were deposited on silicon wafer, as the substrate, using a Plasma Enhanced Chemical Vapor Deposition (PECVD) system. The precursor gases used were 1,3-butadiene, ethylene and ammonia, used at various ratios. Total hydrocarbon (HC) flow rate, FT, was maintained at 10 sccm and gas pressure at 80 Pa. X-ray Photoelectron Spectroscopy (XPS) and chemical derivatisation with 4-trifluoromethylebenzaldehyde XPS were used to determine the N and amine content [-NH2]. Film water stability, defined as % loss in film thickness after 24 h immersion in DI water, was determined by profilometric measurements. Nanoscratch and nanoindentation tests were performed to study the adhesion and the elastic modulus and hardness of the films, respectively. Fg adsorption on films after the 24 h immersion was investigated by scan- and time-measurements of Surface Plasmon Resonance (SPR) spectroscopy. Results and Discussion: The first step in the development of a bio-functional PP film is to optimise the plasma process parameters such as, power, gas flow ratio (R) and HC gas flow ratio (RHC), in order to produce both stable and amine-rich films. This requires an extensive set of experiments, due to the fact that high amine contents tend to lead to increased film solubility, owing to the high affinity of amine-rich surfaces towards polar solvents. Figure 1 shows the effect of RHC and power on the film amine content and stability. Deposition at 20 W results in an increased amine incorporation (Fig 1a) which is attributed to the higher energy input that has led to higher reaction rates. The increase in RHC resulting in a decrease in [-NH2] (Fig 1a) is explained by the increased availability of butadiene that has a lower bond dissociation energy. The high degree of cross-linking introduced by the more unsaturated structure of butadiene results in a more stable PP film (Fig 1b). Once the plasma parameters were optimised, protein adsorption on selected films was investigated and Fg adsorption on these different surfaces was compared. Figure 2 shows the adhesion of Fg on a pure butadiene PP film which was already previously exposed to water for 24 h. The shift in the SPR peak in Fig 2a confirms the successful adsorption of the protein and the time-measurement (Fig 2b) shows that the process stabilises within ~10 min. The concentration of Fg solution used was 2 mg/ml, equivalent to that of blood plasma. Nanoindentation studies of these films show an elastic modulus and hardness of ~10 GPa and ~0.35 GPa, respectively. Conclusion: Butadiene based PP films with reasonably high amine content are found to be fully stable in aqueous media and to promote Fg adsorption. The highly cross-linked nature of butadiene based PP films and relatively high elastic modulus, renders them not only insoluble but also resilient and durable candidates for endovascular coiling applications. Work in progress and future work involves study of mechanical properties, platelet activation and blood coagulation. Natural Sciences and Engineering Research Council of Canada (NSERC); Canada Foundation for Innovation (CFI); Fonds de Recherche du Québec — Nature et Technologies (FRQNT)

Effect of Surface Chemical Functionalities on Collagen Deposition by Primary Human Dermal Fibroblasts.

Surface modification has been identified as an important technique that could improve the response of the body to implanted medical devices. Collagen production by fibroblasts is known to play a vital role in wound healing and device fibrous encapsulation. However, how surface chemistry affects collagen I and III deposition by these cells has not been systematically studied. Here, we report how surface chemistry influences the deposition of collagen I and III by primary human dermal fibroblasts. Amine (NH3), carboxyl acid (COOH), and hydrocarbon (CH3) surfaces were generated by plasma deposition. This is a practically relevant tool to deposit a functional coating on any type of substrate material. We show that fibroblasts adhere better and proliferate faster on amine-rich surfaces. In addition, the initial collagen I and III production is greater on this type of coating. These data indicates that surface modification can be a promising route for modulating the rate and level of fibrous encapsulation and may be useful in informing the design of implantable biomedical devices to produce more predictable clinical outcomes.

Curing characteristics of an epoxy resin in the presence of functional graphite oxide with amine-rich surface

Functional graphite oxide (DGO) with amine-rich surface was successfully prepared through the amidation reaction and characterized by X-ray diffraction analyses (XRD), Fourier transform infrared spectra (FTIR) and Raman spectra. The effects of functional graphite oxide on the curing kinetics of epoxy (EP) were investigated by means of differential scanning calorimetry (DSC). The curing kinetic parameters of EP, EP/graphite oxide (GO) and EP/functional graphite oxide were obtained. There was not much difference in total heat of reaction ΔH and peak temperature Tp with the incorporation of GO or DGO. However, the activation energy, Ea, and the overall order of reaction m+n were enhanced. Comprehensive kinetic analyses indicated that the incorporation of GO sheets brought in an effect of inhibition on curing process. While the inhibition effect weaken when the GO is modified with amine-rich surface. The possible curing mechanism and reaction pathways were proposed to provide a reasonable explanation.

Enhanced mechanical properties of epoxy nanocomposites based on graphite oxide with amine-rich surface

Functional graphite oxide (DGO) with amine-rich surface was synthesized through chemically grafting flexible poly(oxypropylene)diamine, and its epoxy (EP) composites were prepared.

Covalent attachment of 4-amino-1,8-naphthalimides onto the walls of mesoporous molecular sieves MCM-41 and SBA-15

This work describes the covalent grafting of 4-amino-1,8-naphthalimides, which are fluorescent dyes with very interesting optical properties, onto the walls of mesoporous molecular sieves. The mesoporous materials MCM-41 and SBA-15 were first treated with 3-aminopropyltriethoxysilane, generating amine-rich surfaces that were further reacted with 4-amino-1,8-naphthalic anhydride, resulting in yellow fluorescent solids. The success of the modification reactions was confirmed by elemental analysis, X-ray diffraction patterns, infrared spectroscopy, scanning electron microscopy and UV/visible and fluorescence spectroscopy. The emission spectra of the dye bound to MCM-41 was quite insensitive to solvent polarity, in contrast to dye-grafted SBA-15, which showed a high solvent sensitivity. These results suggest a tight fit of the dye molecules within the channels of MCM-41, leaving no room for the solvent molecules. In the case of SBA-15, the large pore size allows the invasion of the channels by solvent molecules, resulting in solvation of the encaged chromophore.