Mesoporous surface functionalization

Fig. 15. Mesopore surface area as a function of pore diameter obtained from mercury intrusion data for PAN derived carbon fiber porous monoliths [28].

Figure 1. Schematic representation of a single-step process that involves a simultaneous template removal from the MCM-41 mesopores and their surface functionalization [17].

Oxidative polymerization of 1,4-diethynylbenzene into highly conjugated poly(phenylene butadiynylene) within the channels of surface-functionalized mesoporous silica and alumina materials. J. Am. Chem. Soc. 124 9040-9041. 

The Effect of Surface Functionalization of Mesoporous Silicas with Propylimidazol on Porosity, Pore Connectivity and Tortuosity. 

Now, an important question is How, those parameters Sp, Vp, (Dmax/2c), c, and x are affected by the gradual narrowing of pores due to some kind of surface functionalization A second question is which of, and how, the parameters t, c and (Dmax/2o) are interrelated. The question becomes more interesting, and perhaps intriguing, since all the above quantities are calculated just from one kind of measurement, namely the N2 adsorption/desorption data. A partly answer to the above question was attempted in a previous work [10] in which sixteen mesoporous vanado-phoshoro-aluminates solids were tested and some relationships between c and (Dmax/2o) were established. A first target of this paper is to extend the search for such possible inter-relations to a class of mesoporous silicas, with a random pore size distribution whose porosity has been systematically and gradually modified by surface fiinctionalization... 

Figure 2. Specific surface area, Sbet (a), and estimated mesoporous surface area (b), StM o, Sbjh, and i Bda , as a function of the weight fraction of microporous material y.

For the five mixtures, the cumulative mesoporous volume, Feds, and mesoporous surface area, S edB, and are both linear decreasing functions of the micropore content y (Figure 2b). The cumulative specific surface area SedB is definitely a better estimator of the mesoporous surface than the specific surface S xt computed Ifom the t-plot. The lUPAC classification states that mesopores are pores whose width is larger that 2 nm. In the case of the cylindrical pore model retained for the pore size distribution, this is equivalent to radii larger than 1 nm. It should however be stressed that the calculation of the cumulative surface and volume of the mesopores must not be continued at lower pressures than the closing of the hysteresis loop (gray zones of Figures 3a and 3b). If a black box analysis tool is used and if the calculation is systematically continued down to 1 nm, severe overestimation of the mesopores surface and volume may occur. 

BJH, Dollimore-Heal and BdB methods were compared for assessment of mesoporosity. Owing to the pore shape of the material used, the first two methods lead to an underestimation of pore size, and hence to an overestimation of total mesoporous surface. The last method is more general, and when the appropriate shape factor is used, a reliable estimation of the mesoporous texture is obtained. The S sdB estimator is almost a perfectly linear function of y, and vanishes in the X(IOO) sample. The external surface area, Xext, computed from the t-plot leads to an overestimation of the true mesoporous surface. 

A comparison of the data in Fig. 2 (Plate A, filled circles) and Fig. 5 (Plate B, open symbols) reveals that the performance of the heat-treated wood-based carbon, even under some preloading conditions, is similar to single solute TCE uptake by coal-based activated carbons in the absence of preloading [9]. The observed effect may result from some combination of optimum surface acidity, optimal type of surface functional group, and/or pore structure effects. The WVB carbon has a mesoporous pore structure, which has been observed to minimize the impacts of preloading in preliminary comparative experiments designed to isolate this effect (data not shown). Future work will employ carbon surface characterization techniques that will allow identification of functional groups and more accurate correlation with surface reactivity. 

Tbe effect of surface functionalization of mesoporous silicas with propylimidazol on porosity, pore connectivity and tortuosity... 

For the accurate characterization of the adsorption phenomena, it is necessary to obtain accurate information on pore stmctures. However, most of ordinary microporous carbons and mesoporous carbons are obtained with amorphous stmctures that are characterized by irregular arrangements of non-uniform pores. X-ray (or electron) diffraction (XRD) techniques are not useful for such carbons because there are no well-defined stmctural factors to correlate with the adsorption behavior. Moreover, porous carbons exhibit wide varieties of the surface functional groups and the thickness of the pore walls, depending on the details of the synthesis conditions. The lack of distinct XRD lines makes it difficult to distinguish stmctural differences between samples which causes many works to depend empirically on specific samples. 

The ability to synthesize carbon nanostmctures, such as fullerenes, carbon nanotubes, nanodiamond, and mesoporous carbon functionalize their surface or assemble them into three-dimensional networks has opened new avenues for material design. Carbon nanostructures possess tunable optical, electrical, or mechanical properties, making them ideal candidates for numerous applications ranging from composite structures and chemical sensors to electronic devices and medical implants. 

The application of MPS in biosensor has received more and more attention in the past few years. It was reported that functionalized mesoporous silica nanomaterials have good biocompatibility to be internalized by animal and plant cells without posing any cytotoxicity issue in vitro [27-29], These findings may generate new types of drug/gene delivery and biosensor, particularly in the development of electrochemical biosensors. We will mainly discuss the advancements in morphology control and surface functionalization of MPS for proteins immobilization and the recent developments of proteins encapsulated MPS biosensors. 

Ania and Bandosz168 evaluated the performance of various ACs obtained from different carbon precursors as adsorbents for the desulfurization of liquid hydrocarbon fuels. According to their results, they concluded that the volume of micropores governs the amount physisorbed and mesopores control the kinetics of the process. They also found that introduction of surface functional groups enhances the performance of the ACs as a result of specific interactions between the acidic centers of the carbon and the basic structure of DBT molecule. 

Several laboratories have developed the methods of mesoporous silica surface functionalization with simultaneous removal of the surfactant and grafting of organic functionalities without prior calcination. A convenient and highly controllable approach to the surface functionalization of mesoporous silica[221] employs an alcoholic solution of... 

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