Polyfurfuryl alcohol

Poly(furfutyl alcohol) (PFA) is an amorphous polymer with a non-graphitizable structure, and potentially a good precursor to prepare CMSM [50]. Because of its simple molecular stracture arrd formation mechanism, it is an appropriate material for fundamental experimerrtal and atomistic simulation studies. Hence, Acharya [51] chose PFA based on the knowledge that PFA derived carbon conld have desirable properties such as rrarrow pore size distribution and chemical stability. However, PFA did not appear to have the best mechanical and elastic properties reqtrired for forming a thin film on a rigid snpport [51]. Since PFA is in liqtrid state at room temperature, it can be rrsed in supported film only. 

PFA was rrsed exterrsively as a precnrsor dnring the preparation of nanoporons carbon (NPC) merrtbrane for gas separation by Foley and co-workers [52-58]. An early work had rmcovered the rrse of a spray-coating techniqne in order to prodnce a thinlayer of NPC inthe pororrs snrface of a stainless steel disk snpport [51,54]. Selectivity for O2/N2 separation of np to 4 was achieved for the snpported membrane carborrized at 600°C in flowing helitrm [54]. Later Foley arrd co-workers improved their preparation techrrique by using an ultrasonic deposition system which conld rrrriformly distribute the polymeric solution on to the support [52, 53, 57], They have fabricated a number of thin film supported nonporous carbon membranes 

SNPCM PFA (wt%) Temperature (K) Time (min) Coats Mass (mg) Thiekness (pm) Additives 

Other studies involving the use of PFA precursor for carbon membrane synthesis were done by Chen and Yang [59], Wang et al. [60], and Sedigh et al. [50]. 

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In principle, molecular sieve carbons (MSC) can be achieved by the pyrolysis of thermosetting polymers such as polyvinylidene chloride, polyfurfuryl alcohol, cellulose, cellulose triacetate, polyacrylonitrile and phenol formaldehyde (Koresh 1980). An example is given by Trimm and Cooper (1970,1973) for the preparation of MSC (mixed with metallic compounds) for catalyst systems. A mixture of furfuryl alcohol, platinum oxide and formaldehyde was heated to 40°C and additional formaldehyde was added to ensure the... 

Sonobe, N., Kyotani, T., and Tomita, A. Formation of graphite thin film from polyfurfuryl alcohol and polyvinyl acetate carbons prepared between the lamellae of montmorillonite. Carbon 29, 1991 61-67. 

The most widely applied method is dipcoating (81). The monoliths are dipped in a precursor solution and subsequently dried, carbonized, and (if necessary) activated. Many different carbon precursors have been used, such as saccharides (56,82,83), polyfurfuryl alcohol (84), phenolic resins, and furanic resins (85,86). 

FIGURE 29 SEM images of carbon ceramic composites made from (A) sucrose (Cord-SUC) (B) polyfurfuryl alcohol (Cord-PFA) (C) carbon nanofibers (Cord-CNF). 

It should be noted that the t-plot analysis shows a very small amount of micropores in the sample studied, which is due to the use of the mesophase pitch as the carbon precursor. It is known that many precursors, e.g., sucrose and polyfurfuryl alcohol, infiltrate well siliceous templates but after carbonization give meso- or macroporous carbons with complementary microporosity. This is not the case for the mesophase pitch, which is used to synthesize carbon fibers that are nonporous materials. 

Carbon molecular sieve membranes have been prepared on porous supports by controlled pyrolysis. For example, Chen and Yang [1994] prepar carbon molecular sieve membranes on porous graphite supports by coating a layer of polyfurfuryl alcohol followed by conu-olled pyrolysis with a Hnal temperature of 50O C. The procedure can be repeated to deposit a desired thickness of the carbon membrane. The choice of a graphite support is partially based on the consideration of the compatibility in thermal expansion between the carbon and the support. 

Carbon molecular sieves, or carbogoric sieves are amorphous materials made by pyrolyz-ing coal, coconut shells, pitch, phenol-formaldehyde resin, or other polymers. EKslocations of aromatic microdomains in a glassy matrix give their porosity. Pores are slit-shaped. Pore structure is controlled by the temperature of the pyrolysis. Pore widths range from 3 A to 10 A. Acarbogenic sieve made from polyfurfuryl alcohol and combined with silica-alumina was selective for monomethylamine production from methanol and ammonia [54]. 

PZC/IEP of Glassy Carbon Obtained by Carbonization of Polyfurfuryl Alcohol... 

The pore structure in molecular sieving carbon is typically ascribed to arise from at least three different mechanisms. In the first the structure of the carbon is derived from the precursor, but in shrunken form. In this way the structure of wood charcoal is similar to the cellular structure of the wood (2). Another type of porosity arises in the fissures and cracks left behind in the carbon matrix. These faults relieve the thermally-induced, mechanical stresses brought on by pyrolysis. Ultramicroporosity can also originate from the volatilization of small molecules. These molecules are formed during pyrolysis, and leave molecularly-sized channels in the solidifying carbon matrix (3-6). Pyrolysis of polyfurfuryl alcohol, polyvinylidenechloride, and polyacrylonitrile lead to the formation of formaldehyde and water, hydrogen chloride, and hydrogen cyanide, respectively. 

The Type III IOM-CMS materials were prepared by modifying the surface of a porous carbon with an inorganic oxide, combining this with polyfurfuryl alcohol, and pyrolyzing the mixture. Each of the examples described below were chosen to... 

In order to determine the composition of the Type Ila materials the samples were oxidized in air. This was done to burn off the carbon and leave behind the metal oxide. By careful weighing before and after the oxidation process, the amounts of carbon and inorganic oxide contained in each sample were calculated. The results of these analyses, as well as the metal alkoxide and polyfurfuryl alcohol conversions, are also... 

Several monolithic enzyme biocatalysts were prepared and characterized with carbon coatings consisting of carbonized sucrose, carbonized polyfurfuryl alcohol, and carbon nanofibers. The coated carbon monoliths were also compared with an integral (composite) carbon monolith. A lipase from Candida antarctica was adsorbed on the monolithic supports. Adsorption on carbon coatings can be very effective, depending on the carbon microstructure. For a high lipase loading. 

TABLE 27.6. Characteristics of the Porous Electrode Structure on the Base of Polyfurfurylic Alcohol... 

Membranes from various manufacturers A, Hollosep-cellulose triacetate hollow fibre membrane (Toyobo) B, sulphonated polysulphone composite hollow fibre membrane (Albane International) C, BlO-aromatic polyamide hollow fibre membrane (Du Pont) D, PEC-1000-composite flat-sheet membrane (foray) E, NS-200-composite polyfurfuryl alcohol membrane F, FT-30-composite polyamide flat-sheet membrane (Film Tec/Dow) G,... 

The acid-base Nafion composite membranes include blends of Nafion with polypyrrole (PPy) [98-104], polybenzimidazole (PBI) [105-107], poly (propyleneoxide) (PPO) [108, 109], polyfurfuryl alcohol (PFA) [110], poly(vinyl alcohol) (PVA) [111-115], sulfonated phenol-formaldehyde (sPF) [116], polyvinylidene fluoride (PVdF) [117-122], poly(p-phenylene vinylene) (PPV) [123], poly(vinyl pyrrolidone) (PVP) [124] polyanifine (PANI) [125-128], polyethylene (PE) [129], poly(ethylene-terephtalate) [130], sulfated p-cyclodextrin (sCD) [131], sulfonated poly(ether ether ketone) (sPEEK) [132-135], sulfonated poly(aryl ether ketone) (sPAEK) [136], poly(arylene ether sulfone) (PAES) [137], poly(vinylimidazole) (PVl) [138], poly(vinyl pyridine) (PVPy) [139], poly (tetrafluoroethylene) (PTFE) [140-142], poly(fluorinated ethylene-propylene) [143], sulfonated polyhedral oligomeric silsesquioxane (sPOSS) [144], poly (3,4-ethylenedioxythiophene) (PEDT) [145, 146], polyrotaxanes (PR) [147], purple membrane [148], sulfonated polystyrene (PSSA) [149, 150], polystyrene-b-poly(ethylene-ran-butylene)-bpolystyrene (SEES) [151], poly(2-acrylamido-2-methyl-l-propanesulphonic acid-co-l,6-hexanediol propoxylate diacrylate-co-ethyl methacrylate) (AMPS) [152], and chitosan [31]. A binary PVA/chitosan [153] and a ternary Nafion composite with PVA, polyimide (PI) and 8-trimethoxy silylpropyl glycerin ether-1,3,6-pyrenetrisulfonic acid (TSPS) has also been reported [154]. 

Liu J, Wang H, Cheng S, Chan KY (2005) Nafion-polyfurfuryl alcohol nanocomposite membranes for direct methanol fuel cells. J Membr Sci 246 95-101... 

C. R. Schmitt, Polyfurfuryl alcohol resins. Polymer-Plast. Technol. Eng. 3, 121 (1974). 

Fabrication of glassy carbon materials is a relatively straightforward, but time consuming process. A preformed polymeric precursor such as phenol-formaldehyde, polyfurfuryl alcohol, polyvinyl alcohol or oxidized polystyrene is slowly heated in an inert atmosphere to a high temperature in excess of 2000 °C. Heating times may be as short as a day or as long as one month. It is not unusual to encounter exothermic temperature regions that must be traversed very slowly (i.e., 1 °C temperature increase per hour) to avoid the nucleation of bubbles. 

Using furfuryl alcohol, recently Pranger and Tarmenbatrm (2008) employed an in situ polymerization approach to produce polyfurfuryl alcohol (PFA) nanocomposites without the use of solvents or surfactants. On the one hand, furfuryl alcohol (FA) has a dual function, serving both as an effective dispersant for MMT clay nanoparticles and as the matrix precursor for the in situ polymerization. 

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