Poly N-vinylcaprolactam

Table 5 Summary of the reaction conditions for poly(N-vinylcaprolactam) (PVCL) grafted with MAC11EO42 [181]... 

Fig. 10 Temperature dependencies of poly(N-vinylcaprolactam) (PVCL) hydrodynamic diameter as a function of surfactant concentration 1 0, 2 0.25, 3 0.5, 4 1, 5 3 mmol/L sodium dodecyl sulfate. (Reprinted with permission from Ref. [37]. Copyright 1998 American Chemical Society)...

The re-entrant phase diagram experimentally observed for proteins has also been observed for a number of water-soluble polymers. As expected, the sidechains of the polymers are able to form hydrogen bond interactions with water. Poly(ethylene oxide) [92] and poly(vinyl methyl ether) [93] form weak hydrogen bonds via their ether groups. Poly(N-vinylpyrrolidone), poly(N-isopropylacrylamide) [94], poly(N-vinylisobutyramide) [94], poly(N-vinylcaprolactam) and poly(2-acrylamido-2-methyl-l-propanamide) [95] contain amide groups in their side chains. It is well known that hydrogen bonds to ethers are much weaker than those formed with amides. It is clear that these polymers also show hydrophobic interactions. 

Ramos, J., Imaz, A., Forcada, J., 2012. Temperature-sensitive nanogels poly(N-vinylcaprolactam) versus poly(N-isopropylacrylamide). Pol3Tner Chemistry 3, 852—856. 

A. Pich, Y. Lu, V. Boyko, K.-F. Arndt, and H.-J.P. Adler, Thermo-sensitive poly (N-vinylcaprolactam-co-acetoacetoxyethyl methacrylate) microgels 2. Incorporation of polypyrrole, Polymer, 44 (25), 7651-7659 (2003). 

Rejinold, N. S., Chennazhi, K. P., Nair, S. V., Tamura, H., Jayakumar, R. (2011). Biodegradable and thermo-sensitive chitosan-g-poly (N-vinylcaprolactam) nanoparticles as a 5-fluorouracil carrier,... 

Pich, A., Y. Lu, et al. (2004). Thermo-sensitive poly(N-vinylcaprolactam-co-acetoacetoxyethyl methacrylate) microgels. 3. Incorporation of polypyrrole by selective microgel sweUing in ethanol-water mixtures. Polymer 45(4) 1079-1087. 

The copolyma miaogel systems based on VGL wae repotted recendy. Wu et al. repotted the synthesis of poly (N-vinylcaprolactam-co-sodium acrylate) miaogels and Boyko et al. synthesized miaogels based on poly (N-vinylcaprolactam-co-N-vinylpyrrolidone). 

Maeda, Y Nakamura T. Ikeda, I. Hydration and phase behavior of poly(N-vinylcaprolactam) and polyjA-vinylpyrrolidone) in water. Macromolecules 2002, 35, 217-222. 

NIP AM has been most widely discussed but other aqueous gels are also thermally responsive, including poly N-vinylcaprolactam (PVCL) and hydroxypropylcellulose (HPC) [99]. In the unswollen (high temperature) state, PVCL is much stiffer than in the swollen state and resembles a glassy polymer, whereas in HPC the modulus decreases as it shrinks. 

Bronstein L, Kostylev M, Tsvetkova I, Tomaszewski J, Stein B, Makhaeva EE, Khokhlov AR, Okhapkin AR Core-shell nanostructures from single poly(N-vinylcaprolactam), Macromolecules Stabilization and Visualization. Langmuir 2005 21 2652-2655. 

Chee CK, Rimmer S, Soutar I, Swanson L (2006) Fluorescence investigations of the conformational behaviour of poly(N-vinylcaprolactam). React Funct Polym 66(1) 1-11. doi 10.1016/j.reactfunctpoplym.2005.07.007... 

However, the development of in vivo applications for PNIPAM is limited by its non-biodegradability and the presence of amide moieties that reduce its biocompatibility. For this reason, other thermo-responsive polymers have been investigated in recent years. Poly(N-vinylcaprolactam) is a promising alternative. This polymer has a LCST between 35 and 38°C, again close to the temperature of the human body, and is characterized by high biocompatibility and low toxicity (Konak et al, 2007 Medeiros et al, 2010 Shtanko et al, 2003 Yanul et al, 2001). Additionally, amphiphilic copolymers such as Pluronics and Tetronics have been developed, based on copolymers of polyethylene oxide and polypropylene oxide. These copolymer systems exhibit a solution-gel transition at close to human body temperature that permits their application as injectable implants (Samchenko et ai,2011). 

Shtanko, N. I., Lequieu, W., Goethals, E. J. and Du Prez, F. E. (2003) pH- and thermo-responsive properties of poly(N-vinylcaprolactam-co-acrylic acid) copolymers . Polymer International, 52,1605-1610. 

In addition to the commonly used synthetic polymers such as pNIPAM and poly(N-vinylcaprolactam) (PVCL), elastin-like polymers were introduced as thermoresponsive polymers for affinity precipitation (Shimazu et al., 2003). An elastin-like polymer consists of the repeating penta-peptide, Val-Pro-Gly-Xaa-Gly (Xaa being any amino acid except proline). It undergoes reversible phase transition under temperature or salt concentration changes similar to pNIPAM (Shimazu et a/., 2003). An elastin-like polymer was used as a terminal tag for the facilitation of recombinant protein purification as attaching it to the hydrolase enzyme improves its purification. Purification, in excess of 1300-fold was achieved after two cycles of reversible changes of elastin-like polypeptide conformation precipitation induced by environmental changes (Shimazu et al., 2003). 

Miserez,B.,Lynen,E, Wright, A.,Euerby,M. and Sandra,P. (2010).Thermoresponsive poly(N-vinylcaprolactam) as stationary phase for aqueous and green liquid chromatography. Chromatographia, 71,1-6. 

Liang X, Kozlovskaya V, Chen Y, Zavgorodnya O, Kharlampieva E (2012) Thermosensitive multilayer hydrogels of poly(N-vinylcaprolactam) as nanothin films and shaped capsules. Chem Mater 24 3707... 

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