ISOPROPYL ACRYLAMIDE COPOLYMER

Uenoyama, S and Hoffman AS. Synthesis and characterization of acrylamide-N-isopropyl acrylamide copolymer grafts on silicone rubber substrates. Radiat. Phys. Chem., 1988, 32, 605-608. 

Kuckling D, Richter A, Amdt K-F (2003a) Temperature and pH dependent swelling behavior of poly(A-isopropyl-acrylamide)-copolymer hydrogels and their use in flow control. Macromol Mater Eng 288 144-151... 

T. Ogata, T. Nonaka and S. Kurihara, Permeation of solutes with different molecular size and hydrophobicity through the poly(vinyl alcohol)-graft-7V-isopropyl acrylamide copolymer membrane, J. Membr. Sci., 1995, 103, 159. 

KI2 Kim, Y.C., Bang, M.-S., and Kim, J.-C., Synthesis and characterization of poly(A/-isopropyl acrylamide) copolymer with methoxy polyethyleneglycol monomethacry-late, J. Ind. Eng. Chem., 12,446, 2006. 

A review is presented on the controlled release of calcitonins from polymeric matrices and oil-based formulations covering the period 1992-8. Polymers covered include biodegradable polymers, such as polyglycolic acid, polylactic acid and copolymers thereof, and non-biodegradable polymers, such as styrene-isopropyl acrylamide copolymers and poly(methacrylic acid-g-ethylene glycol) copolymers, for oral calcitonin delivery systems. 28 refs. 

A -isopropyl acrylamide (N1PA VI) copolymerization by RAFT 529 JV-isopropyl acrylamide (Ml PAV1) polymerization block copolymers 543, 546 with dithiocarbamale photmnitiaior 465... 

The temperature-sensitive poly(A-isopropyl acrylamide) and pH-sensitive poly(methacrylic acid) were used as the two component networks in the IPN system. Since both A-isopropyl acrylamide (NIPAAm) (Fisher Scientific, Pittsburgh, PA) and methacrylic acid (MAA) (Aldrich, Milwaukee, Wl) react by the same polymerization mechanism, a sequential method was used to avoid the formation of a PNIPAAm/PMAA copolymer. A UV-initiated solution-polymerization technique offered a quick and convenient way to achieve the interpenetration of the networks. Polymer network I was prepared and purified before polymer network II was synthesized in the presence of network I. Figure I shows the typical IPN structure. 

Hydrogels synthesized from polymers and copolymers of N-isopropyl acrylamide (NIPAAm) shrink or swell as the temperature is raised or lowered through their lower critical solution temperature (LCST). 

We report here on copolymer hydrogels of N-isopropyl acrylamide (NIPAAm) and acrylamide (AAm) which are crosslinked with mediylene-bis-acrylamide (MBAAm) and which contain the enzyme asparaginase immobilized within the gel. 

Figure 1. Lower critical solution temperatures of copolymers of N-isopropyl acrylamide with other N-alkyl acrylamides as a function of monomer input ratios.

Figure 2. Sephacryl S-400 Chromatogram of Acrylamide/N-isopropyl Acrylamide (10/90) Copolymer.

Figure 3. Turbidity versus Temperature Curves for poly-N-isopropyl acrylamide and its copolymers ...

Figure 5. Lower Critical Solution Temperatures of Copolymers of N-isopropyl Acrylamide and N-n- and N-t-butyl Acrylamide as a Function of Monomer Input Ratios.

Using N-isopropyl acrylamide and acrylamide or other N-substituted acrylamides it is possible to design copolymers that will precipitate at any desired temperature between 0 and 65 C. It is not surprising that acrylamide is the most effective comonomer in raising the LCST. 

Thus, the PEO segment actually becomes hydrophobic at higher temperatures. This temperature-dependent change converts the amphiphilic block copolymer to a water-insoluble hydrophobic polymer (Topp et al. 1997 Chung et al. 2000). The temperature at which the polymer exhibits this transition is called its lower critical solution temperature (LCST). In addition to PEO, substituted poly(A -isopropyl acrylamide) (PNIPAM Chart 2.1) exhibits temperature sensitivity, where the LCST can be tuned by varying the alkyl fimctionahty. The guest encapsulation combined with the temperature-sensitive precipitation of the polymers has been exploited to sequester and separate guest molecules from aqueous solutions (Fig. 2.4). 

Duracher D, Sauzedde F, Elaissari A, Perrin A, Pichot C (1998) Cationic amino-containing A-isopropyl acrylamide-styrene copolymer latex particles 1-particle size and morphology vs. Polymerization process. Colloid Polym Sci 276(3) 219-231... 

Poly(amino acid)s (PAAs) have also been used in drug delivery PEO-(l-aspartic acid) block copolymer nano-associates , formed by dialysis from a dimethyl acetamide solution against water, could be loaded with vasopressin. PLA-(L-lysine) block copolymer microcapsules loaded with fluorescently labelled (FITC) dextran showed release profiles dependent on amino acid content. In a nice study, poly(glutamate(OMe)-sarcosine) block copolymer particles were surface-grafted with poly(A-isopropyl acrylamide) (PNIPAAm) to produce a thermally responsive delivery system FITC-dextran release was faster below the lower critical solution temperature (LCST) than above it. PAAs are prepared by ring-opening polymerisation of A-carboxyanhydride amino acid derivatives, as shown in Scheme 1. 

With the purpose of conferring thermosensitivity to chitosan-based hydrogels. Park et al. proposed the grafting of carboxylic acid-terminated poly(ethylene oxide-h-propylene oxide) block copolymer (Pluronic) onto the primary amine of chitosan, mediated by EDC coupling agent [102]. With the same purpose, Wang et al. grafted poly(N-isopropyl acrylamide) (NiPAM) chains onto chitosan by the copolymerization of acrylic acid-derivatized chitosan and N-isopropylacrylamide (NIPAAm) in aqueous solution [103]. 

Self-organizing block copolymer nanocontainers provide the possibility of entrapping of hydrophobic inhibitors, oils or bioactive materials in the core making them dispersed in water. The sizes of nanocontainers can be controlled by the molecular weight of the polymer and the ratio between the block sizes. The thickness of the block copolymer shells can exceed 50 nm, which leads to a much lower permeability for small molecular weight species. Several amphiphilic block copolymers were investigated as components of the nanocontainers poly(ethylene oxide), poly(7V-isopropyl acrylamide),... 

Zhang, Y., Yarin, Ai., 2009. Stimuli-responsive copolymers of n-isopropyl acrylamide with enhanced longevity in water for micro- and nanofluidics, drug delivery and nonwoven applications. Journals of Materials Chemistry 19, 4732—4739. 

BAR Barker, I.C., Cowie, J.M.G., Huckeby, T.N., Shaw, D.A., Soutar, 1., and Swanson, L., Studies of the smart thermoresponsive behavior of copolymers of A-isopropyl-acrylamide and WA/ -dimethylaciylamide in dilute aqueous solution. Macromolecules, 36, 7765, 2003. 

L12 Liu, R., DeLeonardis, P., Cellesi, F., Tirelli, N., and Saunders, B.R., Cationic temperature-responsive poly(A/-isopropyl acrylamide) graft copolymers From triggered association to gelation, Langmuir, 24, 7099,2008. 

CH2 Chang, Y., Chen, W.-Y., Yandi, W., Shih, Y.-J., Chu, W.-L., Liu, Y.-L., Chu, C.-W., Ruaan, R.-C., and Higuchi, A., Dual-thermoresponsive phase behavior of blood compatible zwitterionic copolymers containing nonionic poly(A-isopropyl-acrylamide). Biomacromolecules, 10, 2092, 2009. 

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