Alternating crystalline-amorphous layers in hybrid block copolymers of linear poly(ethylene glycol) and dendritic poly(benzyl ether)

In the present work, we have studied the crystalline morphology of hybrid di- and triblock copolymers consisting of linear poly(ethylene glycol) (PEG) and Frechet-type monodendrons of poly(benzyl ether). The linear blocks can crystallize to form spherulites under supercooling condition. Using atomic force microscopy and small-angle X-ray scattering method we found alternating crystalline and amorphous layers. The crystalline layers are formed by the PEG block, while the amorphous layers contain the miscible mixture of PEG and the monodendrons. Our analysis shows that the long period, d, of the layers scales as d proportional to M-D(0.2) where M-D is the molecular weight of the monodendrons. As the radius of gyration of the monodendrons R-g, also scales as R-g proportional to M-D(0.2) (B. M. Tande, et al. Macromolecules 2001, 34, 8580), we obtain d proportional to R-g, implying a linear increase of the long period with the radius of gyration of the monodendrons.