Volume 42 - Issue 2 - 237 - 249

Thermosensitive poly(N-isopropylacrylamide) based cryogel: A SAXS study

Isıya duyarlı poli(N-izopropilakrilamit) temelli kriyojellerin SAXS çalışması

The purpose of this study is to observe the structural changes of the thermosensitive poly(N-isopropylacrylamide- N-methacryloyl-L-histidine) poly(NIPA-MAH) monolithic cryogel with changing temperature around lower critical solution temperature (LCST) of NIPA by Small Angle X-Ray Scattering (SAXS). Poly(NIPA-MAH) cryogel was prepared by free radical cryocopolymerization of NIPA with MAH as functional comonomer and N,N- methylene-bisacrylamide (MBAAm) as crosslinker directly in a plastic syringe. Polymerization initiated by N,N,N,N- tetramethylene diamine (TEMED) and ammonium persulfate (APS) pair at subzero temperature in an ice bath. LCST of poly(NIPA-MAH) cryogel was found to be 34oC. Poly(NIPA-MAH) cryogel with 60–100 μm in pore diameter have a specific surface area of 42.6 m2/g polymer. This porous cryogel form provides fast temperature response comparing to conventional gels. The surface morphology and bulk structure of poly(NIPA-MAH) cryogel revealed with scanning electron microscopy (SEM). SAXS allowed the determination of nanoalteration of poly(NIPA-MAH) cryogel such as pore volume, wall thickness and pore shape with changing temperature. Scattering data were analysed both native form and in water at temperature range of 300C-400C. At two different temperatures 34oC and 35oC a detailed investigation on shape of pores and pore size; which indicating a recordable change, were also carried out. 

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