Thermo-responsive polymers temperature sensitivity

Thermo-responsive materials have huge potential for a suite of applications, owing to their responsiveness to an external trigger and the ability to be used in different formats. There are a variety of thermo-responsive polymers that differ in their mechanism of temperature sensitivity and thereby have different properties. These... 

In a previous study, our group synthesized a new temperature and pH-sensitive poly(2-(dimethylamino) ethylmethacrylate-fe-vinylcaprolactam-fc-(2-(dimethylamino) ethyl methacrylate)), PDMAEMA- i-PVCL-fc-PDMAEMA, triblock copolymer by RAFT polymerization. PDMAEMA is dual sensitive (pH and temperature) and its LCST was around 50 °C, while PVCL is a thermo-responsive polymer and its LCST was around 32 °C. By modifying the structure and adjusting the composition of these polymers it is possible reduce the LSCT and pK values in order to ensure compatibility with physiological temperature and pH (see Table 9.1, Triblock 1). The results showed that these polymers can self-assemble into micelles in different environments [60]. 

Hatakeyama H, Kikuchi A, Yamato M et al (2007) Patterned biofunctional designs of thermo-responsive surfaces for spatiotemporally controlled cell adhesion, growth, and thermally induced detachment. Biomaterials 28 3632-3643 Hem DL, Hubbell JA (1998) Incorporation of adhesion peptides into nonadhesive hydrogels useful for tissue resurfacing. J Biomed Mater Res 39 266-276 Huang J, Wang XL, Chen XZ et al (2003) Temperature-sensitive membranes prepared by the plasma-induced graft polymerization of N-isopropylacrylamide into porous polyethylene membranes. J Appl Polym Sci 89 3180-3187... 

Poly(vinyl methyl ether), PVME, is a thermo-sensitive polymer. The aqueous solution has a Lower Critical Solution Temperature (LCST) of 37 °C. Therefore, PVME is soluble in water below its LCST, but insoluble above its LCST. When an aqueous solution of PVME is irradiated with y-rays the solution becomes PVME hydrogel [18, 19]. The gel shows thermo-sensitivity similar to the solution, and swells below 37 °C and shrinks above this temperature. It is important to form a fine porous gel structure to obtain quick response gels. There are two methods for the purpose. One is a method using micro-phase separation by heating. The other is a method using micro-phase separation by blending of polymer solutions. 

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