1 - Vinyl-2-pyrrolidone Crosslinked

Crospovidone PVPP 1-Vinyl-2-pyrrolidone Crosslinked Insoluble Polymer... 

SYNS CROSPOVIDONE PVPP l-VINYL-2-PYRROLIDONE CROSSLINKED INSOLUBLE POLYMER... 

Poly(propylene fumarate) (PPF) networks, which are formed by the reaction of PPF with a crosslinker and initiator, have been investigated as an injectable orthopedic biomaterial. While a number of crosslinkers, such as N-vinyl pyrrolidone (NMP) and poly(ethylene glycol) dimethacrylate, have been... 

Poly(Propylene Fumarate) (PPF) is a linear, unsaturated, hydrophobic polyester (Structure 12) containing hydrolyzable ester bonds along its backbone. PPF is highly viscous at room temperature and is soluble in chloroform, methylene chloride, tetrahydrofuran, acetone, alcohol, and ethyl acetate [66]. The double bonds of PPF can form chemical crosslinks with various monomers, such as W-vinyl pyrrolidone, poly(ethylene glycol)-dimethacrylate, PPF-diacrylate (PPF-DA), and diethyl fumarate [67,68]. The choice of monomer and radical initiator directly influence the degradative and mechanical properties of the crosslinked polymer. Once crosslinked, PPF forms a solid material with mechanical properties suitable for a range of bone engineering applications. 

The hydrogehnatrix can be obtained by y-irradiation, which induces crosslinking simultaneously with the in situ reduction of Ag" ions initiated by the products of water radiolysis (e, OH, H, H, H2, H2O2). For the radiochemical gelation of vinyl pyrrolidone two radical entities are involved in different proportion (Fig. 6). 

Fig. 6 Radical intermediates promoting crosslinking in irradiated vinyl pyrrolidone...

Similar to borax, boronic acid-containing polymers can also be used to crosslink polyhydroxy polymers, such as PVA. Kitano et al. reported the first example of an interpolymer complex based on boronate-diol interactions. The complex was formed by mixing a PVA solution and an alkali solution of poly(AI-vinyl-pyrrolidone-co-3-acrylamidophenylboronic acid). Complex formation leads to an increase in solution viscosity. Above a critical polymer concentration, the complex solution loses its fluidity to become a transparent gel. The authors later increased the solubility of the polymer under physiological and acidic aqueous conditions by incorporation a third comonomer, Af,Af-dimethylaminopropylacrylamide (DMAPAA). Therefore, an interpolymer complex can form at physiological pH. 

An unsaturated polyester with = 140 °C and T = 20 °C has been prepared from 1,4-CHDM and diethyl fumarate by melt poly-condensation. The polyester was then crosslinked using N-vinyl pyrrolidone in the presence of variable amounts of inorganic fillers. The hydrolytic stability of these composites with different compositions was then examined for their potential use as bioresorbable boned cements (27). 

Poly(iV-vinyl pyrrolidone-co-2-hydroxyethyl methacrylate-co-itaconic acid)-Grafted on Trisodium Citrate Crosslinked Cellulose Acetate-coated chitosan [p-g-CT-NagCit-CAc],... 

Jabbari Esmaiel, and Karbasi Saeed. Swelling behavior and cell viability of dehydrother-mally crosslinked poly(vinyl alcohol) hydrogel grafted with N-vinyl pyrrolidone or acrylic acid using y-radiation. J. Appl. Polym. Sci. 91 (2004) 2862-2868. 

Sheet Form Gels. The most common and useful fabrication of ionically conductive polymers for medical applications is the sheet form. The old fashioned gd or paste Qrpe formulations ate deemed to be too messy for most modem applications. The polymers ate synthesized from water soluble monomers in the presence of a chemical crosslinker, water, salt, and humectant by free radical irritated processes. One significant advantage of this approach is that these materials can be formed by a solventless process in substantiauy final form. For example, acrylic add, or mixture of acrylic add and N-vinyl-pyrrolidone ate polymerized to form hydrophilic conductive adhesives that have good adhedve properties on human skin. These polymers also exhibit excellent conductivity prop ties (i 1,12). 

Partially neutndized carboxylated polymer solutions can also be reacted with polyepoxides to crosslink via chemical bond formation yielding tacky electrically conductive hydrogels for biomedical electrodes (31). Low molecular weight di-, tri-, or tetraaldehydes react with N-(3-aminopropyl)methacrylamide/N-vinyl pyrrolidone copolymers to form chemically bonded crosslinks giving hydrogels, adhesives, and coatings (52). 

All SCL basically consist of hydrophilic polymers that maintain then-gel structure, with the ability to swell and not dissolve by intermolecular crosslinking. Therefore, natural polymers, such as agarose and gelatin, are potential candidates for its material. However, currently commercially available SCL are made only of copolymers of methacrylic acid derivatives, mainly PHEMA, and several other monomers because of stability and safety concerns. Lenses with a water content of 30-40 % are made mostly of PHEMA and those with water contents of70-80 % are made of copolymers ofN-vinyl pyrrolidone (NVP), acrylamide (AAm), HEMA, and methacrylic acid (MA). There are also poly(vinyl alcohol) derivatives. Table 2 shows the names and chemical structures of various SCL components [6]. 

Anderson, C. C., Rodriguez, F., Thurston, D. A. (1979). Crosslinking aqueous poly(vinyl pyrrolidone) solutions by persulfate. Journal of Applied Polymer Science, 23, 2453-2462. 

A limited number of studies have been performed on crosslinked polypyrrolidone and vinyl pyrrolidone-silicone copolymers [46] and l-vinyl-2-pyrrolidone-l-vinyl 3-methyl imidozolonium chloride copolymer [47]. 

Hydrogels can be prepared conveniently with the aid of yrays, starting with aqueous solutions of the respective monomer [16]. The process consists of two radiation-induced steps (i) polymerization of the monomer and (ii) crosslinking of the polymer formed in the first step (see Section 5.2.1). In fact, the process can commence with the OH radical-induced polymerization of monomers. With prolonged irradiation, the initially formed macromolecules such as poly(vinyl pyrrolidone) and polyacrylamide undergo crosslinking by OH radical attack [15,115]. 

A fluid loss additive for hard brine environments has been developed [1685], which consists of hydrocarbon, an anionic surfactant, an alcohol, a sulfonated asphalt, a biopolymer, and optionally an organophilic clay, a copolymer of N-vinyl-2-pyrrolidone and sodium-2-acrylamido-2-methylpropane sulfonate. Methylene-bis-acrylamide can be used as a crosslinker [1398]. Crosslinking imparts thermal stability and resistance to alkaline hydrolysis. 

Poly(methyl acetoxy silylene) [poly(MASi)] is also claimed [130] to initiate the polymerization of cyclohexyl methacrylate upon UV irradiation and to crosslink the resulting polymer by air exposure. Finally, the pyridinium salt of partially chloromethylated poly(methyl phenyl silylene) (Q-PMPSi) is reported [131] to initiate the polymerization, in aqueous solution, of hydrophilic vinyl monomers such as methacrylic acid, acrylamide, 2-hydroxyethyl methacrylate and 1 -vinyl-2-pyrrolidone. 

Davis, T.P. Huglin, M.B. Yip, D.C.F. Properties of poly(V-vinyl-2-pyrrolidone) hydrogels crosslinked with ethyleneglycol dimethacrylate. Polymer 1988, 29, 701-706. 

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