Notes Crystal Orientation within Lamellae-Forming Block Copolymers of Semicrystalline Poly(4-vinylpyridine)-b-poly(E-caprolactone) Ya-Sen Sun, † Tsai-Ming Chung, ‡ Yi-Jing Li, ‡ Rong-Ming Ho,* ,‡ Bao-Tsan Ko, § and U-Ser Jeng † National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan; Department of Chemical Engineering, National Tsing-Hua UniVersity, Hsinchu 30013, Taiwan; and Material and Chemical Research Laboratories, Industrial Technology Research Institute, Hsinchu 30013, Taiwan ReceiVed April 27, 2007 ReVised Manuscript ReceiVed June 27, 2007 Introduction Because of diverse morphologies upon controls over com- positions and segregation strength limits of constituting blocks, semicrystalline diblock copolymers have been employed as templates to explore the crystallization behavior of polymer chains confined in nanoscale space provided that crystallizable blocks crystallize within preexisting microdomains (MD) driven by microphase separation, for which the crystallization tem- perature T C lies below the temperature T ODT for the order- disorder transition. 1-16 The number of available possible conformations reduces because the restricted geometries im- posed on crystallizing polymer materials are on a nanometer scale, which is approximately the length of a polymer chain in coil form. 3-16 Therefore, the nanoscaled confinement size plays an important role in crystallization kinetics. 9e,16,17 Our previous work indicated that a distinct transformation of isothermal crystallization kinetics, from heterogeneous to homogeneous nucleation, occurred between two neighboring glassy lamellar layers when the confined size became less than 8 nm (equivalent to the size of forming a stable nucleus via heterogeneous nucleation), leading to an abrupt shift in crystallization to a low- temperature region. 16 On the other hand, altering the confined size led to variances in crystallographic orientation upon changing confined space. 9e,16 In this extended Note, three distinct confined spaces of 6, 8.8, and 11 nm were constructed upon varying the molar mass of diblock copolymers to explore a correlation between crystal orientations and confined spaces within vitrified lamellar MD of crystalline-amorphous (C-A) block copolymers in strong segregation limits with T ODT (order- disorder transition temperature of the microphase separation) . T g a (glass transition temperature of the amorphous block) > T C c (crystallization temperature of crystallizable blocks). In addition to the perpendicular and random orientations for the 11 and 6 nm confined sizes reported previously, 16 the parallel orientation found at an intermediate level of confinement (8.8 nm) was analyzed in detail. Experiments Materials. Three P4VP-PCL block copolymers of VP/CL 146/ 91, 69/46, and 56/38 were used to explore the crystal orientation and melting behavior under nanoscale confinement; the PCL domains had thicknesses 11 (VP/CL 146/91), 8.8 (VP/CL 69/46), and 6 nm (VP/CL 56/38). The detailed synthetic routes and characterizations of the synthesized copolymers were described elsewhere. 16 All bulk samples of block copolymers with long-range * To whom correspondence should be addressed: e-mail rmho@ mx.nthu.edu.tw; Tel 886-3-5738349; Fax 886-3-5715408. † National Synchrotron Radiation Research Center. ‡ National Tsing-Hua University. § Industrial Technology Research Institute. Figure 1. (a) Geometry of the rimming-flow induced P4VP-PCL copolymers with a lamellar MD. Sets of 2D SAXS patterns of VP/CL 69/46 at 80 °C with the X-ray beam along directions (b) X, (c) Y, and (d) Z. Figure 2. 2D WAXD patterns of oriented VP/CL 69/46 samples isothermally crystallized at 10 (a, e), 20 (b, f), 30 (c, g), and 40 °C (d, h). The left WAXD patterns were recorded with the beam along the Y-direction and the right ones along the Z-direction. 6778 Macromolecules 2007, 40, 6778-6781 10.1021/ma0709708 CCC: $37.00 © 2007 American Chemical Society Published on Web 08/10/2007