Copolymers temperature-responsive

Many kinds of nonbiodegradable vinyl-type hydrophilic polymers were also used in combination with aliphatic polyesters to prepare amphiphilic block copolymers. Two typical examples of the vinyl-polymers used are poly(/V-isopropylacrylamide) (PNIPAAm) [149-152] and poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) [153]. PNIPAAm is well known as a temperature-responsive polymer and has been used in biomedicine to provide smart materials. Temperature-responsive nanoparticles or polymer micelles could be prepared using PNIPAAm-6-PLA block copolymers [149-152]. PMPC is also a well-known biocompatible polymer that suppresses protein adsorption and platelet adhesion, and has been used as the hydrophilic outer shell of polymer micelles consisting of a block copolymer of PMPC -co-PLA [153]. Many other vinyl-type polymers used for PLA-based amphiphilic block copolymers were also introduced in a recent review [16]. 

In 1997, Kim and coworkers first developed biodegradable IP systems using a triblock copolymer of PEG and PLLA, PEG-b-PLLA-b-PEG, and demonstrated sustained release of drugs from the hydrogel [127]. After this achievement, many kinds of biodegradable amphiphilic block copolymers (including multiblock copolymers) exhibiting temperature-responsive sol-gel transition have been reported [137, 308-318]. In this review, only several recent results are introduced. 

Nonetheless, one cannot exclude the probability of a successful combination of these prerequisites (as was the case with poly[(NiPAAm-co-GMA)-g-PEO considered above]) that will allow us to obtain, using the chemical colouring approach, the protein-like HP-copolymers with a dense hydrophobic core wrapped by the hydrophilic shell. Such a shell should be capable of efficiently protecting the temperature-responsive macromolecules against pronounced interchain hydrophobic interactions and precipitation at temperatures significantly higher than those at which the copolymers of the same total monomer composition—but with a non-protein-like primary sequence of comonomer units—are in the soluble state. 

Kanazawa, H., Kashiwase, Y, Yamamoto, K., Matsushima, Y, Kikuchi, A., Sakurai, Y, and Okano, T. Temperature responsive liquid chromatography 2. Effect of hydrophobic groups in A-isopropylacrylamide copolymer-modified silica, Anal. Chem., 1997, 69, 823-830. 

In addition, temperature-responsive properties of PNIPAAm have also been used in fabricating molecular ion gating membranes.37 38 In these studies, the concept of an ion gating molecular recognition membrane using synthetic host substances and a thermosensitive polymer was proposed. Figure 15.1038 illustrates the concept. The membrane was prepared by plasma graft copolymerization, which filled the pores of a porous polyethylene him with a copolymer of A -isopropyl... 

Figure 8. Acid catalyzed thermolysis of the t-BOC protected copolymer is responsible for the change in solubility. The quantum efficiency for generation of the phenolic is the product of the efficiency of photoacid generation and the catalytic chain length. Exposure generates a local concentration of acid. Subsequent heating to a temperature below that at which uncatalyzed thermolysis occurs allows local acidolysis of the t-BOC protecting group.

Kuckling D, Harmon M, Frank CW (2002a) Photo cross-linkable PNIPAAm copolymers 1 synthesis and characterization of constrained temperature-responsive hydrogel layers. Macromolecules 35 6377-6383... 

Kuckling D, Hoffman J, Plotner M, Ferse D, Kretschmer K, Adler HJP, Arndt KF, Reichelt R (2003b) Photo cross-linkable PNIPAAm copolymers 3 microfabricated temperature responsive hydrogels. Polymer 44 4455 462... 

Y. Kaneko, R. Yoshida, K. Sakai, Y. Sakurai and T. Okano, Temperature-responsive shrinking kinetics of poly(Y-isopropylacrylamide) copolymer gels with hydrophilic and hydrophobic comonomers, J. Membr. Sci., 1995, 101, 13 Y.H. Lim, D. Kim and D.S. Lee, Drug releasing characteristics of thermo- and pH-sensitive interpenetrating polymer networks based on poly(W-isopropylacrylamide), J. Appl. Polym. Sci., 1997,... 

Qiao M, Chen D, Ma X, Liu Y. Injectable biodegradable temperature-responsive PLGA PEG-PLGA copolymers Synthesis and effect of copolymer composition on the drug release from the copolymer-based hydrogels. Int J Pharm 2005 294 103 112. 

Tungchaiwattana, S., Liu, R., Kalacheva, S., Shahidan, N.N., Kells, A., Saunders, B.R., 2013. Mixmres of pH-responsive microgels and temperature-responsive star-like copolymers from heteroaggregation to gelation. Soft Matter 9, 35—47. 

D12 Ding, H., Wu, F., Huang, Y., Zhang, Z., arrd Nie, Y., Synthesis and characterization of temperature-responsive copolymer of PELGA modifred poly(V-isopropyl-... 

MUN Mun, G.A., Nurkeeva, Z.S., Akhmetkalieva, G.T., Shmakov, S.N., Khutoiyanskiy, V.V., Lee, S.C., and Park, K., Novel temperature-responsive water-soluble copolymers based on 2-hydroxyethylaciylate and vinyl butyl ether and their interactions with poly(carboxylic acids), J. Polym. Set Part B Polym. Phys., 44, 195, 2006. 

HE1 He, C., Zhao, C., Chen, X., Guo, Z., Zhtrang, X., and Jing, X., Novel pH- and temperature-responsive block copolymers with tunable pH-responsive range, Macromol. Rapid Commun., 29, 490, 2008. 

KHU Khutoryanskaya, O.V., Mayeva, Z.A., Mun, G.A., and Khutoryanskiy, V.V., Designing temperature-responsive biocompatible copolymers and hydrogels based on 2-hydroxyethyl(meth)acrylates, Biomacromolecules, 9, 3353,2008. 

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. 

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