Inclusion interaction of highly densely PEO grafted polymer brush and α-cyclodextrin

Inclusion interaction of highly densely PEO grafted polymer brushes with a-cyclodextrins (alpha-CDs) has been investigated in this study. The polymers grafted with poly(poly(ethylene oxide) macromonomers) were prepared through the "grafting from" approach by atom transfer radical polymerization (ATRP) of poly(ethylene glycol) methyl ether methacrylate, PEOMA, from a well-defined poly(macroinitiator), poly(2-(2-bromoisobutyryloxy)ethyl methacrylate) (PBIEM, M-w/M-n = 1.27; degree of polymerization of backbone DPb = 157). The inclusion complexation of this type of polymer brush with alpha-CD was studied by X-ray diffraction (XRD), H-1 NMR, electron diffraction (ED), scanning electron microscope (SEM), differential scanning calorimetry (DSC), and tbermogravimetric analyses (TGA). For polymer brushes from PEOMA of M-n = 475, i.e., PBIEM-g-P(PEOMA475), hydrogels were formed because of the interaction of inclusion complex columns. The column-type crystalline structures of the hydrogels were confirmed by XRD measurement. The hydrogels showed unique temperature-dependent sol-gel phase transition. The interaction of polymer brush from PEOMA of M. = 300, i.e., PBIEM-g-P(PEOMA300), with alpha-CD resulted a low yield complex of uniform crystals with luster in aqueous solution. The ED analysis combined with optical microscope and XRD showed that these crystals were hexagonal crystals with columnlike structure.