Hydroxypropylcellulose polymer

Bonnet-Gonnet C, Leikin S, Chi S, Rau DC, Parsegian VA. Measurement of forces between hydroxypropylcellulose polymers temperamre favored assembly and salt exclusion. J. Phys. Chem. B 2001 105 1877-1886. 

Properties. Hydroxypropylcellulose [9004-64-2] (HPC) is a thermoplastic, nonionic cellulose ether that is soluble in water and in many organic solvents. HPC combines organic solvent solubiUty, thermoplasticity, and surface activity with the aqueous thickening and stabilising properties characteristic of other water-soluble ceUulosic polymers described herein. Like the methylceUuloses, HPC exhibits a low critical solution temperature in water. 

An erodible insert developed as a potential ocular drug-delivery system is marketed as a prescription drug for the lubricant properties of the polymer base. Lacrisert is a sterile ophthalmic insert used in the treatment of moderate to severe dry eye syndrome and is usually recommended for patients unable to obtain symptomatic relief with artificial tear solutions. The insert is composed of 5 mg of hydroxypropylcellulose in a rod-shaped form about 1.27 mm diameter by about 3.5 mm long. No preservative is used, since it is essentially anhydrous. The quite rigid cellulose rod is placed in the lower conjunctival sac and first imbibes water from the tears and after several hours forms a... 

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). 

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

Figure 2 illustrates the temperature dependence of the swelling degree as a function of precursor polymer type. Methylcellulose (MC), hydroxypropyl-methylcellulose, type E (HPMC-E) and hydroxypropylmethylcellulose, type K (HPMC-K) gels have comparable effective crosslink densities of about 2 x 10 5 mol/cm3 (as determined from uniaxial compression testing), while the crosslink density of the hydroxypropylcellulose (HPC) gel is about half this [52]. The transition temperature for each gel is within several degrees of the precursor polymer lower critical solution temperature (LCST), except for the MC gel, which has a transition temperature 9 °C higher than the LCST. The sharpness of the transition was about 3%/°C, except for the HPC gel transition, which was much sharper - about 8%/°C. 

P. Navard, Formation of band textures in hydroxypropylcellulose liquid crystals, J. Polym. Sci., Phys. Ed., 24,435 (1986). 

Adhesive polymers used in oral patches include poly(hydroxyethylcellulose), poly (hydroxypropylcellulose), poly(sodium carboxymethylcellulose), poly(acrylic acid), poly(methacrylic acid), polyvinylpyrrolidone) and poly (vinyl alcohol). 

A popular approach to improve ocular drag bioavailability is to incorporate soluble polymers into an aqueous solution to extend the drug residence time in the cul-de-sac. It is reasoned that the solution viscosity would be increased and hence solution drainage would be reduced. The more commonly used viscolyzing agents include PVA and derivatives of cellulose. Cellulosic polymers, such as methylcellulose, hydroxyethylcellulose (HEC), hydroxypropyl-methylcellulose (HPMC) and hydroxypropylcellulose (HPC), are widely used as viscolyzers showing Newtonian properties. They have common properties ... 

Fig. 20 Force of adhesion of hydroxypropylcellulose hot-melt extruded films containing various polymer additives (12 subjects, n — 6). (From Ref l)...

Wirick MG. Study of the enzymic degradation of CMC and other cellulose ethers. / Polym Sci 1968 6(Part A-1) 1965-1974. Anonymous. Final report on the safety assessment of hydroxy-ethylcellulose, hydroxypropylcellulose, methylcellulose, hydroxypropyl methylcellulose and cellulose gum. / Am Coll Toxicol 1986 5(3) 1-60. 

Solid state characterization of the structure and deformation behavior of water-soluble hydroxypropylcellulose. J. Polymer Sci. A-2, 7, 1197 (1969). 

The resolution and the sharpness of the patterns were strongly influenced by the irradiation conditions. On example of the temperature-sensitive polymer hydroxypropylcellulose (HPC LOST in water of 41°C (Kley 1971)) and PNIPAAm, we investigated the influence of the acceleration voltage on the back-scattering and the proximity effect (Arndt et al. 2009). In closely packed patterns, the primary beam generates back-scattered electrons causing an over- or under-exposure in the resulting pattern. The so-called proximity effect is seen in the contour line in Fig. 19. It influences the spatial resolution of the structure. 

The same group has also obtained composite materials based on imogolite and water-soluble polymers such as hydroxypropylcellulose (HPC) and poly (vinylalcohol) (PVA) [32]. HPC is a rigid rod polymer that has a cholesteric phase, whereas PVA is a random coil amorphous polymer. Significantly enhanced mechanical properties were only obtained in the case of the HPC composite materials. 

Ozeki, T. Yuasa, H. Kanaya, Y. Application of the solid dispersion method to the controlled release of medicine. IX. Difference in the release of flurbiprofen from solid dispersions with poly(ethylene oxide) and hydroxypropylcellulose and interaction between medicine and polymers. Int. J. Pharm. 1997, 115 (2), 209-217. 

Table 1.3 shows, for example, the surface tension of the solutions of some water-soluble polymers at 25°C (0.1% aqueous solutions of the polymers). Hydroxypropylcellulose (HPC) is a good example of a surface-active polymer. Water solutions greatly reduced surface and interfacial tensions. HPC functions as an assistant in both emulsifying and whipping. HPC combines organic solvent solubility, thermoplasticity and surface activity with the aqueous thickening and stabilizing properties of other water soluble cellulose pol miers. 

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