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오늘 본 자료
Molecular Level Ordering in Poly(2‐vinylpyridine)
Changez, Mohammad,Koh, Haeng‐,Deog,Kang, Nam‐,Goo,Kim, Jin‐,Gyu,Kim, Youn‐,Joong,Samal, Shashadhar,Lee, Jae‐,Suk WILEY‐VCH Verlag 2012 Advanced Materials Vol.24 No.24
<P><B>The reaction between atactic poly(2‐vinylpyridine) and 1,4‐dibromobutane</B> leads to formation of long‐range 3D molecular ordering in polymer chains mainly because the side group (pyridine) of the polymer chain changes to a syndotactic configuration. This may enable the production of functional molecular devices that operate on a 3D atomic scale.</P>
Reversible and pH-Sensitive Vesicles from Amphiphilic Homopolymer Poly(2-(4-vinylphenyl)pyridine)
Changez, Mohammad,Kang, Nam-Goo,Lee, Chi H.,Lee, Jae-Suk WILEY-VCH Verlag 2010 Small Vol.6 No.1
<B>Graphic Abstract</B> <P>The sigma bond between the 2-phenyl pyridine head groups and the vinyl backbone of poly(2-(4-vinylphenyl)pyridine) allows for free rotation of the head groups in response to the polymer's environment (see image) and the hydrophobic vinyl backbone provides curvature for the formation of bilayer vesicles with a 1-nm membrane thickness. The homopolymer vesicles act as a reservoir for both hydrophobic and hydrophilic molecules, individually or simultaneously. <img src='wiley_img/16136810-2010-6-1-SMLL200901670-content.gif' alt='wiley_img/16136810-2010-6-1-SMLL200901670-content'> </P>
Preparation of Ag-Embedded Polystyrene Nanospheres and Nanocapsules by Miniemulsion Polymerization
Koh, Haeng-Deog,Changez, Mohammad,Lee, Jung-Pil,Lee, Jae-Suk WILEY-VCH Verlag 2009 Macromolecular Rapid Communications Vol.30 No.18
<P>An isopropyl myristate (IPM) biocompatible oil and an IPM solution of dodecanethiol-capped Ag nanoparticles (NPs, 4.5 nm) were used as hydrophobes to suppress the Ostwald ripening of monomer/hydrophobe miniemulsified droplets in a surfactant-stabilized water phase. The formation of non-IPM-encapsulated nanospheres (48 nm) and IPM-encapsulated nanocapsules (90 nm) were precisely controlled by using a water-soluble and an oil-soluble initiator, respectively, in the presence of a pure IPM as a hydrophobe in miniemulsion polymerization. Well-defined PS nanospheres, on which surfaces were coated with Ag NPs (Ag/PS nanospheres, 65 nm), and nanocapsules encapsulating both NPs and IPM liquid phase (Ag-IPM/PS nanocapsules, 115 nm) were made by replacing the hydrophobe from pure IPM with Ag/IPM solution. These nanostructures were characterized by transmission and scanning electron microscopes.</P><P> <img src='wiley_img/10221336-2009-30-18-MARC200900222-gra001.gif' alt='wiley_img/10221336-2009-30-18-MARC200900222-gra001'> </P> <B>Graphic Abstract</B> <P>Ag-coated PS nanospheres (left) and Ag/liquid (isopropyl myristate, IPM)-encapsulated nanocapsules (right) were synthesized by miniemulsion polymerization in the presence of a water-soluble KPS and an oil-soluble AIBN initiator. An IPM solution containing dodecanethiol-capped Ag NPs acts as a hydrophobe to suppress Ostwald ripening of miniemulsified droplets. <img src='wiley_img/10221336-2009-30-18-MARC200900222-content.gif' alt='wiley_img/10221336-2009-30-18-MARC200900222-content'> </P>
Exploration of the Mechanism for Self-Emulsion Polymerization of Amphiphilic Vinylpyridine
Kumar, Santosh,Kim, Dong-Woo,Lee, Hong-Joon,Changez, Mohammad,Yoon, Tae-Ho,Lee, Jae-Suk American Chemical Society 2013 Macromolecules Vol.46 No.18
<P>A rare self-assembly behavior is observed in a hydrophilic monomer (4-vinylpyridine) (4VP) when polymerized in water with a hydrophilic initiator that results in the production of monodisperse polymeric nanoparticles in a single step. This behavior mimics the behavior obtained with the more commonly reported amphiphilic block copolymers. The synthesis and self-assembly of homopolymer nanoparticle from 4VP without the use of any cross-linker, stabilizing agent, surfactant, or polymeric emulsifier are described along with fundamental aspects of the mechanism of this polymerization. This facile and robust procedure enabled the production of highly monodisperse P4VP nanoparticle with a tunable size ranging from 80 to 445 nm. For the first time, we have investigated the growth mechanism of these polymeric nanoparticles to clarify the mechanism of polymeric nanoparticle formation. This work also provides direct visible evidence through transmission electron microscopy (TEM) images at the nanometer scale, which helps in obtaining a better understanding of the mechanism of self-assembly. The effect of temperature on the size of the polymeric nanoparticles was also examined along with the effect of initiator, monomer, and solvent concentrations. We therefore report a versatile and scalable process for the production of monodisperse polymeric nanoparticles, which we call self-emulsion polymerization (SEP).</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/mamobx/2013/mamobx.2013.46.issue-18/ma4017373/production/images/medium/ma-2013-017373_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ma4017373'>ACS Electronic Supporting Info</A></P>