Amphiphilic Carbonaceous Material Research Articles

Characterization of carbonaceous gel beads prepared in presence of polymer using water-in-oil emulsion

Carbonaceous gel beads were prepared by addition of polymers using ammonia water of amphiphilic carbonaceous material through water-in-oil emulsion. By addition of poly(vinylalcohol), carbonaceous gel beads having dimples were obtained, where the number and size of dimples were dependent on the additive amount and molecular weight of poly(vinylalcohol). However, only beads with smooth surfaces were obtained by addition of poly(vinylpyrrolidone) and poly(ethyleneglycol). The morphology of beads is significantly influenced by interfacial tension at the water-oil interface. The surface area of beads prepared by addition of polymers remarkably increased by heat treatment from 5 m 2 g −1 to 289 m 2 g −1 and a pore size of about 20 Å was predominantly produced in the case of PVA. In addition, the carbonaceous gel prepared by addition of PVA exhibited a high graphitizability, similar to that of green cokes. Thus, it was found that physicochemical properties of gel beads prepared by addition of PVA are significantly altered.

Characterization of Carbonaceous Gel and Gel Beads

Carbonaceous gel was prepared from the alkaline solution dissolving amphiphilic carbonaceous material. Gelation of the amphiphilic carbonaceous materials dependedon concentration of the amphipihlic carbonaceous material and the alkaline solution. This so-called carbonaceous gel showed a reversible transformation between sol and gel with temperature. That is, this gel has a quasi-stable structure like agar.Moreover, a carbonaceous dry gel was prepared by drying the carbonaceous gel. This carbonaceous dry gel gave a different thermal behavior from that of the original amphiphilic carbonaceous material.Carbonaceous gel beads were prepared by a new method termed “water in oil emulsion method” using the alkaline aqueous solutions dissolving the amphiphilic carbonaceous materials. These beads had spherical shape and smooth surface. However, the surface morphology and area of the beads were changed by heat-treatment. Especially, by heat-treatment at 900°C the gel beads prepared from aqueous solution of potassium hydroxide became rough surface and had over 400 times larger surface area than as-prepared.

Characterization of organo-carbonaceous gel

Organo-carbonaceous gel was prepared and characterized by various techniques. The organo-carbonaceous gel formed in some polar organic solvents showed a similar thermal behavior to that of an amphiphilic carbonaceous material. The X-ray diffraction measurements demonstrated that the graphitizability of the organo-carbonaceous gel was greater than that of an aqua-carbonaceous gel prepared in alkaline aqueous solution. Further, carbon-metal composites were prepared from the organo-carbonaceous gel containing an organic metal compound such as Pd(acac) 2, Ru(acac) 3, or Ni(acac) 2, followed by heat treatment. Fine metal particles obtained were uniformly dispersed in the carbon matrix.