Polymer thermoresponsive

2 Types of Smart Polymer Surfaces 2.1 Thermoresponsive Polymers 

Several other thermally responsive systems can be cited, such as poly- or oligo(ethylene glycol) methacrylate (OEGMA) derivatives [33 13], We recently showed that copolymers of 2-(2-methoxyethoxy)ethyl methacrylate (MEO2MA) and OEGMA exhibited a LCST in water that can be adjusted to physiological 

In this complex system, when the pH was lowered, the anilinium nitrogen atom was protonated and the CB[6] rings lifted to the top of the stalk. The consequence was the opening of the pores, leading to the dmg release. When the pH was then raised, the nitrogen atoms were deprotonated and this led to the detachment of the CB[6] rings from the stalk. 

In 1982, an azo-dye-containing copolymer of 2-hydroxymethyl methacrylate was used for modulation of lysozyme adsorption on polymer beads. The amount of the protein adsorbed on a microsphere decreased upon irradiation, but rather long 

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Keywords Colloidal stability Globule Mesoglobule Thermoresponsive polymers Abbreviations... 

In a series of papers, Matsuda et al. [291-295] employed RAFT-SIP with immobilized benzyl N,N-diethyldithiocarbamate to form polymer brushes from styrene, methacrylamides, acrylamides and acrylates, NIPAM and N-vinyl-2-pyrrolidone on various surfaces. The SIP is initiated by UV irradiation of the surface-bonded dithiocarbamates. Thermoresponsive polymer brushes were prepared by the polymerization of NIPAM and investigated by XPS, wetting experiments and mainly SPM [294]. Patterned polymer brush layers were also prepared. When chloro-methyl styrene was used as a comonomer, RAFT-SIP resulted in branching. By control of the branching, spatio-resolved hyperbranching of a controllable stem/ branch design was realized (Fig. 9.32) [293, 295]. 

Miyamura et al. [170] and Kanaoka et al. [171] have succeeded in stabilizing Au clusters on polymer supports for aerobic oxidation at room temperature in the mixed solvent of water-benzotrifluoride and in water, respectively. Polymer supports could also offer new functions, such as a recycling system by using a thermoresponsive polymer-supported Au catalyst [171]. 

Cammas, S., K. Suzuki, Y. Sone, Y. Sakurai, K. Kataoka, and T. Okano. 1997. Thermoresponsive polymer nanoparticles with a core-shell micelle structure as site sped c drug cadrifientrol. Rel.48 ... 

Lavigne MD, Pennadam SS, Ellis J et al (2007) Enhanced gene expression through temperature profile-induced variations in molecular architecture of thermoresponsive polymer vectors. J Gene Med 9 44—54... 

Twaites BR, CdLH A, Lavigne M et al (2005) Thermoresponsive polymers as gene delivery vectors cell viability, DNA transport and transfection studies. J Control Release 108 472-483... 

Several thermoresponsive polymer coatings have been applied in the chromatographic separation of biomolecules. The group of Okano has been active in the field for some time. In recent work, silica beads modified with PNIPAM brushes prepared... 

PNIPAM and its copolymers are not the only options for thermoresponsive stationary HPLC phases. Poly(acrylates) and poly(methacrylates) bearing OEG groups in the side chains are known as thermoresponsive polymers that offer some advantages over PNIPAM [40]. Such polymers were recently employed for the modification of silica monoliths, which then served as stationary phase in the HPLC separation of steroids [193], Unsurprisingly, the results were qualitatively similar to those obtained for PNIPAM-based systems, but the separation of relatively hydrophilic steroids was superior. 

Fig. 15 Specific protein separation by a smart thermoresponsive polymer coating. Left PNIPAM with immobilized lactose and RCA 120 is below the LCST. The moieties are separated and, therefore, proteins from the mobile phase can bind to RCA120. Right PNIPAM below LCST. Polymer-bound lactose and RCA120 come into close contact and lactose displaces the protein. Reprinted, with permission, from [194]. Copyright (2003) American Chemical Society...

Among stimuli-responsive or thermoresponsive polymer microspheres, poly(N-isopropylacrylamidc) (PNIPA) was investigated most intensively. Cross-linked PNIPA is a thermosensitive hydrogel which undergoes a volume phase transition at its lower critical solution temperature (LCST) of around 34 °C. Several authors reported the synthesis of PNIPA microspheres [68-73]. 

Capila I, Linhardt RJ (2002) Heparin-protein interactions. Angew Chem Int Ed 41 391 12 Carmeliet P (2003) Angiogenesis in health and disease. Nat Med 9 653-660 Chen CP, Imanishi Y, Ito Y (1998) Effect of protein and cell behavior on pattern-grafted thermoresponsive polymer. J Biomed Mater Res 42 38-44 Cheng XH, Canavan HE, Stein MJ et al (2005) Surface chemical and mechanical properties of plasma-polymerized N-isopropylacrylamide. Langmuir 21 7833-7841 Curti PS, de Moura MR, Veiga W et al (2005) Characterization of PNIPAAm photografted on PET and PS surfaces. Appl Surf Sci 245 223-233... 

Takezawa T, Mori Y, Yoshizato K (1990) Cell-culture on a thermoresponsive polymer surface. Bio-Technology 8 854-856... 

Classic examples of synthetic polymers exhibiting an aqueous LCST include poly-diethyl acrylamide), poly(dimethylaminoethyl methacrylate), poly(A -acryloylpyrrolidine), poly(2-isopropyl-2-oxazoline), elastin-like artificial polypeptides, poly(vinyl methyl ether) and poly(7V-isopropylacrylamide) (PNIPAM, Scheme 1). The latter has been by far the most studied and applied thermoresponsive polymer and therefore can be considered as the gold standard in this field of research. During the last decades, several thousands of research articles and patents described the synthesis, the properties and the applications of this fascinating macromolecule. 

However, despite its widespread popularity in material science, PNIPAM has inherent disadvantages such as an irreversible phase transition and, for short polymers, a significant influence of end-groups on the thermal behavior. Moreover, strictly speaking, PNIPAM is not a bio-inert polymer. Indeed, the presence of multiple secondary amide functions in the molecular stracture of PNIPAM may lead to the formation of cooperative H-bonding interactions with other amide polymers, in particular with proteins. Thus, the design of new types of thermoresponsive polymers is a cracial topic in contemporary polymer chemistry. 

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