A -Isopropyl acrylamide

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

Figure 9 The equations of motion (TF theory) correlate swelling of poly(A-isopropyl acrylamide) caused by an increase in temperature from 10 to 25°C. D = 2.5 X 10 7 cm2/s L0 = 1.5 mm. (Adapted from Ref. 84.)...

Figure 11 Aqueous equilibrium swelling of cross-linked poly(A-isopropyl acrylamide-co-butyl methacrylate) as a function of temperature. Ww, Wp are the weight of water and polymer of swollen polymer network respectively. (From Ref. 32.)...

STRUCTURE AND SOLUTE SIZE EXCLUSION OF POLY(METHACRYLIC ACID)/POLY(A/-ISOPROPYL ACRYLAMIDE) INTERPENETRATING POLYMERIC NETWORKS... 

Structure and Solute Size Exclusion of Poly(methacrylic acid)/Poly(A -isopropyl acrylamide) Interpenetrating Polymeric Networks... 

Poly(A-isopropyl acrylamide) (PNIPAAm) is the most extensively studied temperature-sensitive polymer [10-20]. Crosslinked PNIPAAm exhibits drastic swelling transition at its lower critical solution temperature... 

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. 

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... 

Recently, Zhang and Kumacheva [43] introduced poly(A-isopropyl acrylamide-acrylic acid-2-hydroxyethyl acrylate) [poly(NIPA-AAc-HEA)] microgel particles... 

Block terpolymers prepared by Cheng [5] consisting of poly(A-isopropyl acrylamide-b-polyethyleneoxide-b-A-isopropyl acrylamide), (II), were effective as thermally reversible gels and used as subcutaneous implants, joint or tissue spacers, and biological filler for wrinkles or cosmetic implants. Methacrylamide analogues were prepared by Gutowska [6]. 

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. 

Like PNlPAAm and some other acrylamide derivative polymer gels, the poly (NlPAAm-co-AAmPA) gels swell at low temperature and de-swell at elevated temperature. At pH 2.1.5 the comonomer is completely protonated. The hydrophi-licity of the comonomer is very similar to A-isopropyl acrylamide (NIP A Am). No differences in the swelling curves could be seen. At pH 7.7 the comonomer is charged. The degree of swelling is strongly affected by the copolymerization ratio. The transition behaviour under these circumstances is not very well pronounced (Beebe et al. 2000). 

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... 

Keywords Tissue engineering Cell culture Poly(A-isopropyl acrylamide) Biohybrid material Heparin Star-poly(ethylene glycol) Angiogenesis... 

Hydroxypropylcellulose-g-poly(A -isopropyl-acrylamide)-g-poly(aciylic acid) water 2009LIX... 

Poly(A -acryloylpyrrolidine-Z)-A -isopropyl- acrylamide) water 2007SKR... 

Poly(sulfobetaine methacrylate-co-A -isopropyl-acrylamide) water 2009CH2... 

Poly [A -isopropylacry lamide-co-N- 3 -aminopropy l)methaciy lamide hydrochloride-6-A/ -isopropyl-acrylamide] potassium chloride and water 2009MA1... 

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. 

QIN Qin, S., Geng, Y., Discher, D.E., and Yang, S., Temperature-controlled assembly and release from polymer vesicles of poly(ethylene oxide)-Z>/oc -poly(A/-isopropyl acrylamide), (7v. Mater., 18, 2905, 2006. 

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. 

CRJ Cristiano, C.M.Z., Soldi, V., Li, C., Aimes, S.P., Rochas, C., Pignot-Paintrand, I., and Borsali, R., Thermo-responsive copolymers based on poly(A-isopropyl acrylamide) and poly[2-(methacryloyloxy)ethyl phosphotylcholine] Light scattering and microscopy experiments, Macromol. Chem. Pltys., 210, 1726, 2009. 

A A-isopropylacrylamide-bound hydroxamic acid copolymer 34 was prepared by the reaction of poly(A-isopropyl acrylamide)-co-(2-acryl-oxysuccinimide) with 6-aminohexanehydroxamic acid [95], This water-soluble copolymer quantitatively separates from aqueous solution after Fe uptake and its concentration is reduced from 15.5 ppm to 116 ppb. Poly(hydroxamic acid) beads prepared from polymethacrylate strongly complex Cu(II), Fe(III) and Pb(II) at pH 5 [96], In addition, Co(II), Cu(II) and Fe(II) were selectively eluted from the resin at pH 4, and Pb(II) and Ni(II) with 4 M HNO3. 

Temperature-responsive behavior was also observed for gels formed by worm-like micelles of poly(styrene)-bZocA -poly(iV-isopropyl acrylamide). Poly(iV-isopro-pyl acrylamide) molecules are known to associate when the ambient temperature is increased above their lower critical solubihty temperature (LCST) of 32 °C [215]. When the gel was heated to a temperature above the LCST of the poly(A-isopropyl acrylamide) block, a nanofibrillar network was formed [167, 177]. The association of poly(A-isopropyl acrylamide) was reversible [215] cooling of the nanofibrillar gel led to dissociation of the polymer network. 

Furthermore, addition of hydrophobic ibuprofen resulted in a collapse of all of the gels. The latter is analogous to the findings by Scherlund et al. on the temperature-induced gelation of PEO-PPO-PEO block copolymers on addition of lidocaine and prilocaine in their base forms (see Figure 1.14), as well as to the findings by Carlsson et al. on pH-dependent reductions of the cloud points of poly(A -isopropyl acrylamide) solutions on addition of either lidocaine or prilocaine (215). 

Chitosan-g-poly(A-isopropyl- acrylamide) sodium chloride and water sodium iodide and water 2010BAO 2010BAO... 

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