Hydroxypropylcellulose, preparation

H. Yokota, Alkalization mechanism of cellulose in hydroxypropylcellulose preparation process, J. Appl. Polym. Sci., 32 3423 (1986). 

These stabilizers are added to the formulation in order to stabilize the emulsion formed during particle preparation. These stabilizers, however, can also influence the properties of the particles formed. The type and concentration of the stabilizer selected may affect the particle size. Being present at the boundary layer between the water phase and the organic phase during particle formation, the stabilizer can also be incorporated on the particle surface, modifying particle properties such as particle zeta potential and mucoadhesion (203). Other polymers have also been evaluated as stabilizers in earlier studies such as cellulosic derivatives methylcellu-lose (MC), hydroxyethylcellulose ( ), hydroxypropylcellulose (HPC), and hydroxypropylmethylcellulose (HPMC), as well as gelatin type A and B, carbomer and poloxamer (203). 

Hydroxyalkyl celluloses are obtained in the reaction of cellulose with alkene oxides or their corresponding chlorohydrins. The reaction is a base-catalyzed SN2-type substitution, and the reaction rate is proportional to the product [epoxide][CelI—O3]. The commercial preparations include hy-droxyethyl- and hydroxypropylcellulose for which ethylene oxide and propylene oxide are used as reagents. Hydroxyethylcellulose is formed according to the following equation ... 

Hydroxyethylcellulose (HEC) and hydroxypropylcellulose (HPC) are prepared by reacting cotton linter or woodpulp with aqueous sodium hydroxide, and the resulting alkali cellulose is reacted with ethylene oxide and propylene oxide, respectively. 

Fukui, E., Uemura, K., and Kobayashi, M. (2000), Studies on applicability of press-coated tablets using hydroxypropylcellulose (HPC) in the outer shell for timed-release preparations, I. Controlled Release, 68, 215-223. 

Most research into the study of dispersion polymerization involves common vinyl monomers such as styrene, (meth)acrylates, and their copolymers with stabilizers like polyvinylpyrrolidone (PVP) [33-40], poly(acrylic acid) (PAA) [18,41],poly(methacrylicacid) [42],or hydroxypropylcellulose (HPC) [43,44] in polar media (usually alcohols). However, dispersion polymerization is also used widely to prepare functional microspheres in different media [45, 46]. Some recent examples of these preparations include the (co-)polymerization of 2-hydroxyethyl methacrylate (HEMA) [47,48],4-vinylpyridine (4VP) [49], glycidyl methacrylate (GMA) [50-53], acrylamide (AAm) [54, 55], chloro-methylstyrene (CMS) [56, 57], vinylpyrrolidone (VPy) [58], Boc-p-amino-styrene (Boc-AMST) [59],andAT-vinylcarbazole (NVC) [60] (Table 1). Dispersion polymerization is usually carried out in organic liquids such as alcohols and cyclohexane, or mixed solvent-nonsolvents such as 2-butanol-toluene, alcohol-toluene, DMF-toluene, DMF-methanol, and ethanol-DMSO. In addition to conventional PVP, PAA, and PHC as dispersant, poly(vinyl methyl ether) (PVME) [54], partially hydrolyzed poly(vinyl alcohol) (hydrolysis=35%) [61], and poly(2-(dimethylamino)ethyl methacrylate-fo-butyl methacrylate)... 

Besides the traditional wet granulation, surface adsorbents, especially porous materials, are very helpful for maintaining liquid in a granulation. For example, calcium silicate, a fine porous powder, has been successfully used to adsorb an oily medicine, tocopheryl nicotinate. Due to the high capillarity of the pores inside calcium silicate, the adsorbent has an excellent liquid-holding ability. In the formulation preparation, after drug dissolved in ethanol was adsorbed on calcium silicate, hydroxypropylcellulose (HPC) was added to the mixture and granulated to improve flowability. 

Repka, M.A. Gerding, T.G. Repka, S.L. McGinity, J.W. Influence of plasticizers and drugs on the physical-mechanical properties of hydroxypropylcellulose films prepared by hot-melt extmsion. Drug Dev. Ind Pharm. 1999,25 (5), 627-635. 

Ishikawa T, Mukai B, Shiaishi S, et al. Preparation of rapidly disintegrating tablet using new types of microcrystalline cellulose (PH-M series) and low-substituted hydroxypropylcellulose or... 

Kawashima Y Takeuchi H, Hi no T, Niwa T, Ohya M. Preparation of prolonged-release matrix tablet of acetaminophen with pulverized low-substituted hydroxypropylcellulose via wet granulation. Int J Pharm 1993 99 229-38. 

Tablets for vaginal use have included hydroxypropylcellulose or sodium carboxy-methylcellulose and poly(acrylic acid) (such as Carbopol 934) as excipients. Micropatches in the size range fO-fOO,am in diameter prepared from starch, gelatin, albumin, collagen...

From Butoxide, in One Step A solution of titanium butoxide in ethanol, final concentration 0.0016 M (sample A) or 0.0025 M (sample B) was slowly added under nitrogen to a dispersion of Stober silica in ethanol containing water, final concentration 0.25 M (sample A) or 0.36 M (sample B) at room temperature. Sample C was prepared with final concentrations of titanium butoxide of 0.0091 M, and of water of 0.3 M. The reagents were mixed rapidly, and refluxed for 3 h in the presence of 0.005 mass% of hydroxypropylcellulose. 

Cellulose ethers can be prepared by various methods, as by using the common Williamson ether synthesis, with alkyl halides in the presence of a strong base (Fig. 32). This procedure is most often used to introduce carboxyl functions [O-carboxymethylcellulose (CMC)] or hydroxyl groups [3-hydroxypropylcellulose (HPC) and 2-hydroxyethylcellulose (HEC)]. 

Preparation and characterization of PANI/NiO nanocomposite using various surfactants, e.g., polyvinyl alcohol and hydroxypropylcellulose, were reported by Aleahmad et al. [230]. PANl and NiO were electro-codeposited from aniline and NiSO through cyclic voltammetric scans at controlled acidity leading thus to the formation of PANI/NiO composite film [231]. The stability of NiO in the composite films against acidic environments was found to be enhanced in comparison with the corresponding stability of pure NiO. Electrochemical catalytic behavior of PANl/NiO composite film was demonstrated by the catalytic oxidation of methanol and ethanol. Multicolored electrochromic thin films of... 

Hydroxypropylcellulose Single Tg SEM Miscible when blends were prepared by coprecipitation Khutoryansky et al. (2004)... 

Hydroxyethylcellulose (HEC) and hydroxypropylcellulose (HPC) are prepared by nucleophilic ring opening of ethylene oxide and propylene oxide, respectively, by the hydroxyl anions on the anhydroglucose ring of cellulose. Reactions are conducted commercially in caustic aqueous slurry processes (72). Laboratory methods recently have been reported for preparation of cellulose ethers, esters, and carbamates imder homogeneous reaction conditions in organic solvents (88-91). Such solvents may lead to development of new commercial processes for cellulose derivatives with more imiform substitution. 

Preparation of Copper Sulfide and Gold Nanoparticles Dispersed in Hydroxypropylcellulose—Silica Film with Gas Diffusion Method... 

Many other cellulose derivatives were studied and, among them, acetoxyproylcellu-lose (APC) was found to develop a thermotropic cholesteric phase as well as a lyotropic phase, in several organic solvents, at room temperature. Gray et at [18] prepared this cellulose derivative by the acetylation of hydroxypropylcellulose (a schematic of the chemical reaction is shown in Figure 8.3). 

Fig. 1 (a) Amorphous budesonide particles produced by evaporating an ethanoUc solution of budesonide and hydroxypropylcellulose at atmospheric pressure, (b) Crystalline budesonide particles prepared by addition of water to a sonicated ethanoUc solution of budesonide, (c) Crystalline budesonide particles prepared by addition of water to a sonicated ethanolic solution of budesonide and hydroxypropylcellulose... 

Titania particles are prepared by hydrolysis of titanium tetrabuthoxide (TBOT). TBOT, distilled water, EtOH and hydroxypropylcellulose (HPC) are used as starting materials, the molar ratio of TBOT/HaO/EtOH being 1/7.5/100. HPC is dissolved in a half amount ofEtOH, and then TBOT is added to the solution. Water and the rest ofEtOH are mixed, and then the two solutions are mixed and stirred at 25°C for 17 h. The titania particles formed in the solution are centrifuged and washed with EtOH by repeating the procedure of dispersion and centrifugation three times, and then washed with H2O in the same way. The particles are re-dispersed in H2O and hydrothermally treated at 250°C under 5 MPa for 1 h in an autoclave. The hydrothermally treated particles are separated by centrifugation and vacuum-dried. The resultant particles are heat-treated in air at 600°C for 17 h. 

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