N-Isopropylacrylamide, polymers

Braun, O. Selb, J. Candau, F. Synthesis in mieroemulsion and characterization of stimuli-respon-sive polyelectrolytes and polyampholytes based on N-isopropylacrylamide. Polymer 2001, 42 (21), 8499-8510. 

Lowe, T. L., Virtanen, J. and Tenhu, H., Interactions of drugs and spin probes with hydrophobically modified polyelectrolyte hydrogels based on N-isopropylacrylamide. Polymer, 40, 2595-2603 (1999). 

Chee CK, Rimmer S, Soutar I, Swanson L (2001) Fluorescence investigations of the thermally induced conformational transition of poly(N-isopropylacrylamide). Polymer 42 (12) 5079-5087. doi 10.1016/s0032-3861(00)00821-l... 

Lokuge, L, Wang, X., Bohn, P. W. 2007. Temperature-controlled flow switching in nanocapillary array membranes mediated by poly(N-isopropylacrylamide) polymer brushes grafted by atom transfer radical polymerization, 23 305-311. 

Wang, X., Tu, H., Braun, RV., and Bohn, P.W 2006. Length scale heterogeneity in lateral gradients of poly(N-isopropylacrylamide) polymer brushes prepared by surface-initiated atom transfer radical p>olymeiization coupled with in-plane electrochemical potential gradients. Tanomuir 22 817-823. 

Uludag H, Norrie B, Kousinioris N, Gao T (2001) Engineering temperature-sensitive poly(N-isopropylacrylamide) polymers as caniCTs of therapeutic proteins. Biotechnol Bioeng... 

BOK Bokias, G., Staikos, G., and Hiopoulos, L, Solution properties and phase behaviour of copol uners of acrylic acid with N-isopropylacrylamide, Polymer, 41, 7399, 2000. 

Hirano T, Katnikubo T, Okumura Y, et al. Heterotactic-specific radical polymerization of N-isopropylacrylamide and phase transition behavior of aqueous solution of heterotactic poly (N-isopropylacrylamide). / Polym Sd Part A Polym Chem. 2009 47 2539-2550. 

BG Kabra, SH Gehrke. Synthesis of fast response poly(N-isopropylacrylamide) gels. Polym Commun 32 322-323, 1991. 

R Kishi, O Hirasa, H Ichijo. Fast responsive poly(N-isopropylacrylamide) hydrogels prepared by gamma-ray irradiation. Polym Gels Networks 5 145-151, 1997. 

SH Gehrke, LH Lyu, MC Yang. Swelling, shrinking, and solute permeation of temperature-sensitive N-isopropylacrylamide gel. Polym Prepr 30 482-483, 1989. 

Polymers BA Butylacrylate, CHP 3-chloro-2-hydroxypropyl, DADMAC Diallyldimethylammonium chloride, DMAEA Dimethylaminoethylacrylate,DMAEM Dimethylaminoethylmethacrylate, EM Epichlorohydrin Modified, EIMAOETMAC Hydroxymethacryloxyethyltrimethylammoniumc chloride, MAOEDMAC Methacryloxyethyldimethylammonium chloride, MAOETMAC Methacryloxyethyltrimethylammonium chloride, MDMAEM Methyldimethylaminoethylacrylate, M2VP l-methyl-2-vinylpyridinium bromide,M4VP l-methyl-4-vinylpyridinium bromide,NIPAM N-isopropylacrylamide,PEI Polyethyleneimine, Q Quaternary, VBTMAC Vinylbenzyltrimethylammonium chlroide,VP Vinylpyridinium. 

Grafting can also provide the monolithic polymers with rather unexpected properties. For example, the two-step grafting procedure summarized in Fig. 7, which involves the vinylization of the pore surface by reaction of the epoxide moiety with allyl amine, and a subsequent in situ radical polymerization of N-isopropylacrylamide (NIPAAm) initiated by azobisisobutyronitrile within these pores leads to a composite that changes its properties in response to external temperature [76]. 

Poly(N-isopropylacrylamide) (polyNIPAAM), formed by a free radical polymerization of N-isopropylacrylamide, is a water soluble, temperature sensitive polymer. In aqueous solution, it exhibits a lower critical solution temperature (LCST) in the range of 30-35 C depending on the concentration and the chain length of the polymer. Thus, as the solution temperature is raised above the LCST, the polymer undergoes a reversible phase transition characterized by the separation of a solid phase which redissolves when the solution temperature is lowered below the LCST. Its physicochemical properties have been investigated by several laboratories (1-3). 

The first step in the process was to covalently incorporate biologically active protein molecules into this polymer. Methods analogous to previous reports (4-6) involved first adding a functional group to the protein that would provide it with the ability to polymerize, such as a vinyl or substituted vinyl group, followed by copolymerization with the N-isopropylacrylamide monomer in aqueous solution using N,N,N, N -tetramethylethylenediamine and... 

Considering the rather complicated processes that take place during dissolution it is not surprising that some systems show peculiar behavior. For example, while solubility generally increases with temperature, there are also polymers that exhibit a negative temperature coefficient of solubility in certain solvents. Thus, poly(ethylene oxide), poly(N-isopropylacrylamide), or poly(methyl vinyl ether) dissolve in water at room temperature but precipitate upon warming. This behavior is found for all polymer-solvent systems showing a lower critical solution temperature (LCST). It can be explained by the temperature-dependent... 

Rzaev ZM, Dinner S, Pi kin E (2007) Functional copolymers of N-isopropylacrylamide for bioengineering applications. Prog Polym Sci 32 534-595... 

The second example used visible light absorption that increased the temperature locally within the thermosensitive gel [39]. The gel consisted of a covalently cross-linked copolymer network of N-isopropylacrylamide and chloro-phyllin, a combination of a thermo-sensitive gel and a chromophore. In the absence of light, the gel volume changed sharply but continuously as the temperature was varied. Upon illumination the transition temperature was lowered, and beyond a certain irradiation threshold the volume transition became discontinuous. The phase transition was presumably induced by local heating of polymer chains due to the absorption and subsequent thermal dissipation of light energy by the chromophore. The details will be discussed in a later section. 

At present, we believe that the jump transitions observed in many of the gels studied here represent first order phase transitions. If this is the case, then the gels studied here are among the first found so far in which a first order phase transition occurs near room temperature in pure aqueous solvent with substantial added salt. Early studies by Tanaka s group with poly(acrylamide) based gels required that hydrophobic solvents such as acetone be added for a discontinuous phase transition to be observed near room temperature [6-10]. The more recently studied gels based on poly(n-isopropylacrylamide) [11, 12] and other lower critical solution temperature polymers show discrete phase transitions in water with no salt [11], but the swelling transitions become continuous when moderate amounts of salt are added [12],... 

Many different types of responsive gels have been synthesized by various techniques. Copolymerization/crosslinking of monofunctional and polyfunctional monomers has been extensively used to produce responsive gels of vinyl monomers, especially of a wide variety of acrylamide derivatives such as N-isopropylacrylamide, acrylic acid, and diethylacrylamide [4-11, 21-36]. Crosslinking of linear polymers by either chemical means or y-radiation has also been used to produce a wide range of responsive gels. The precursor polymers... 

Fig. la, h. Chemical structure of poly N-isopropylacrylamide (a) and of trisodium salt of copper chlorophyllin molecule (b). The chlorophyllin molecule has a double bond which can be covalently connected to the polymer networks... 

B h2o2 NIPAM- [PW12O40]3 (NIPAM = N-isopropylacrylamide-based polymer)... 

Another beneLt of polymeric surfactants over traditional surfactants is the potential for much lower CMCs. Amphiphiles with a high CMC may not be suitable as drug-targeting devices since they are unstable in an aqueous environment and easily dissociate upon dilution (Jones and Ler-oux, 1999). It must be noted that while some polymers exhibit very low CMCs, for instance, the CMC of poly -benzyl-L-aspartate) (PEO-PBLA), poly(N-isopropylacrylamide-polystyrene (PNIPA-PST), and poly(caprolactone) (PEO-PCL) are between 0.00005% and 0.002% (La etal.,... 

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