JV-Isopropylacrylamide

A large number of researches have been carried out in order to obtain biocompatible hydrophilic surfaces by introducing water-soluble polymer grafts, including polyethylene glycol), polyacrylamide and poly(vinyl alcohol). It was, however, occasionally observed that there is an optimum in the number of grafted chains for the surface to exhibit the best biocompatibility. The discussions in Sect. 3 will present an approach to a possible elucidation of this problem. A very unique property of poly(JV-isopropylacrylamide) as thermores-ponsive hydrogel will also be discussed in this chapter. 

A large number of macromolecules possess a pronounced amphiphilicity in every repeat unit. Typical examples are synthetic polymers like poly(l-vinylimidazole), poly(JV-isopropylacrylamide), poly(2-ethyl acrylic acid), poly(styrene sulfonate), poly(4-vinylpyridine), methylcellulose, etc. Some of them are shown in Fig. 23. In each repeat unit of such polymers there are hydrophilic (polar) and hydrophobic (nonpolar) atomic groups, which have different affinity to water or other polar solvents. Also, many of the important biopolymers (proteins, polysaccharides, phospholipids) are typical amphiphiles. Moreover, among the synthetic polymers, polyamphiphiles are very close to biological macromolecules in nature and behavior. In principle, they may provide useful analogs of proteins and are important for modeling some fundamental properties and sophisticated functions of biopolymers such as protein folding and enzymatic activity. 

JV-isopropylacrylamide (NIPA) gel is a tyincal example of gels which shows a thermoshrinking type of phase transition in aqueous solutions [2]. As shown in Fig. 1, an increase in the temperature causes this particular gel to shrink by one order of magnitude. 

M.B. Huglin, Y. Liu and J.L. Velada, Thermoreversible swelling behavior of hydrogels based on /V-isopropylacrylamide with acidic comonomers, Polymer, 1997, 38, 5785 M.K. Yoo, Y.K. Sung, C.S. Cho and Y.M. Lee, Effect of polymer complex formation on the cloud-point of poly(JV-isopropylacrylamide) (PNIPAAm) in the poly(NIPAAm-co-acrylic acid) polyelectrolyte complex between poly(acrylic acid) and poly(ally-lamine), Polym., 1997, 38, 2759. 

Poly(5,6-benzo-2-methylene-1,3-dioxepane-co-jV-isopropylacrylamide) water 2007REN... 

Poly[jV-isopropylacrylamide-co-(A, A -dimethyl- amino)propylmethacrylamide] water 2000B02... 

WIN Wintgens, V. and Amiel, C., Physical gelation of amphiphilic poly(JV-isopropylacrylamide) Influence of the hydrophobic groups, Macromol. Chem. Phys., 209, 1553, 2008. 

Poly(jV-isopropylacrylamide-co-aciyloyloxypropylphosphinic acid) water 2004NON... 

Poly(jV-isopropylacrylamide-co-acryhc acid-co-ethyl methacrylate) 157, 463... 

Poly(jV-isopropylacrylamide-co- aciylamide-co-hydroxyethyl methacrylate) water LLE 117... 

Ozturk N, Girotti A, Kose GT, Rodriguez-Cabello JC, Hasirci V (2009) Dynamic cell culturing and its application to micropattemed, elastin-like protein-modified poly(JV-isopropylacrylamide) scaffolds. Biomaterials 30 5417-5426... 

Functional copolymers of Rzaev ZMO, JV-Isopropylacrylamide-based random. 2007 [60]... 

It would be of interest to add some functionalities such as properties in response to changes in pH, temperature, electrical potential and so on as well as hydrophilic properties to PTFE surfaces by the combined technique just described. Poly(AT-isopropylaoylamide) (PNIPA ) is a well-known thermo-responsive polymer whose hydrogel undergoes a volume change around 31 C in an aqueous solution. And further, poly 2-(dimethylamino)ethyl methacrylate (PDMA) in a pH 10 buffer solution exhibits a drastic decrease in the transmittance around 28 °C, which is considered to come from a phase transition of PDMA chains (ii). Therefore, we have tried to prepare JV -isopropylacrylamide (NIPAAm) or 2-(dimethylamino)ethyl... 

Ebara M, Yamato M, Hirose M, Aoyagi T, Kikuchi A, Sakai K, Okano T (2003) Copolymerization of 2-carboxyisopropylacrylamide with JV-isopropylacrylamide accelerates cell detachment from grafted sirrfaces by reducing temperature. Biomacromolecirles 4(2) 344-349... 

Wei, H., Cheng, S.-X., Zhang, X.-X., and Zhuo, R.-X. (2009) Thermo-sensitive polymeric micelles based on poly(JV-isopropylacrylamide) as drug carriers. Progress in Polymer Science, 34, 893-910. 

Hietala S, Nuopponen M, KaUiomaki K, Tenhu H. Thermoassociating poly(JV-isopropylacrylamide) A—B—A stereoblock copolymers. Macromolecules. 2008 41 2627-2631. 

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