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Mix-and-Match Assembly of Block Copolymer Blends in Solution
Cho, Arah,La, Yunju,Jeoung, Sungeun,Moon, Hoi Ri,Ryu, Ja-Hyoung,Shin, Tae Joo,Kim, Kyoung Taek American Chemical Society 2017 Macromolecules Vol.50 No.8
<P>The chemical structure of a block copolymer (BC?) dictates the size, shape, and function of its self-assembled structure in solution. This direct correspondence demands precision synthesis of a specific BCP with optimized structural parameters to obtain the desired nanostructures with structural and functional complexity by solution self-assembly. Here we show that the binary blends of BCPs self-assemble into the desired nanostructure in solution by adjusting the composition of the blend. By modifying the structural parameters of a binary BCP blend through control of the composition, two BCPs sharing the repeating units in both polymer blocks coassemble into the desired structures, which range from spherical micelles to inverse cubic and hexagonal mesophases. These BCP blends not only allow the direct creation of complex periodic mesoporous structures of the desired periodicity and pore size but also provide nanostructures of unprecedented morphology by simple solution self-assembly without relying on the synthesis of correspondingly designed BCPs.</P>
Cho, Arah,La, Yunju,Shin, Tae Joo,Park, Chiyoung,Kim, Kyoung Taek American Chemical Society 2016 Macromolecules Vol.49 No.12
<P>Inverse bicontinuous cubic (IBC) structures consisting of triply periodic minimal surfaces of block copolymers (BCPs) are emerging as materials of interest owing to their structural characteristics, which resemble those of their biological counterparts constructed from lipids. Solution self-assembly of amphiphilic BCPs with nonlinear architectures has recently been shown to form colloidal particles (polymer cubosomes) and macroscopic monoliths having mesoporous networks of water channels embedded in the periodic minimal surfaces of the BCP bilayers. Here we report that BCP architectures play a crucial role in controlling the packing parameter (P) of BCPs; a value greater than unity is a prerequisite for preferential self-assembly into IBC mesophases in solution. We show that the branched architecture of the polymer blocks constituting the BCP critically influences the structural parameters, such as the molecular area and, in particular, the critical length of the hydrophobic domain. Adjusting these structural parameters not only increases the P value of the BCP without depending on the asymmetry of the volume ratio of two polymer blocks (block ratio) but also dictates the lattice and periodicity of the resulting minimal surfaces of the BCPs. Our results could provide a rationale to design and synthesize amphiphilic block copolymers to directly self-assemble into periodic porous structures in solution, which could be promising materials having highly ordered mesopore networks.</P>
An, Tae Hyun,La, Yunju,Cho, Arah,Jeong, Moon Gon,Shin, Tae Joo,Park, Chiyoung,Kim, Kyoung Taek American Chemical Society 2015 ACS NANO Vol.9 No.3
<P>Solution self-assembly of amphiphilic block copolymers into inverse bicontinuous cubic mesophases is an emerging strategy for directly creating highly ordered triply periodic porous polymer nanostructures with large pore networks and desired surface functionalities. Although there have been recent reports on the formation of highly ordered triply periodic minimal surfaces of self-assembled block copolymer bilayers, the structural requirements for block copolymers in order to facilitate the preferential formation of such inverse mesophases in solution have not been fully investigated. In this study, we synthesized a series of model block copolymers, namely, branched poly(ethylene glycol)-<I>block</I>-polystyrene (bPEG-PS), to investigate the effect of the architecture of the block copolymers on their solution self-assembly into inverse mesophases consisting of the block copolymer bilayer. On the basis of the results, we suggest that the branched architecture of the hydrophilic block is a crucial structural requirement for the preferential self-assembly of the resulting block copolymers into inverse bicontinuous cubic phases. The internal crystalline lattice of the inverse bicontinuous cubic structure can be controlled <I>via</I> coassembly of branched and linear block copolymers. The results presented here provide design criteria for amphiphilic block copolymers to allow the formation of inverse bicontinuous cubic mesophases in solution. This may contribute to the direct synthesis of well-defined porous polymers with desired crystalline order in the porous networks and surface functionalities.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2015/ancac3.2015.9.issue-3/nn507338s/production/images/medium/nn-2014-07338s_0013.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn507338s'>ACS Electronic Supporting Info</A></P>
Triclosan-immobilized polyamide thin film composite membranes with enhanced biofouling resistance
Park, Sang-Hee,Hwang, Seon Oh,Kim, Taek-Seung,Cho, Arah,Kwon, Soon Jin,Kim, Kyoung Taek,Park, Hee-Deung,Lee, Jung-Hyun Elsevier 2018 APPLIED SURFACE SCIENCE - Vol.443 No.-
<P><B>Abstract</B></P> <P>We report on a strategy to improve biofouling resistance of a polyamide (PA) thin-film composite (TFC) reverse osmosis (RO) membrane <I>via</I> chemically immobilizing triclosan (TC), known as a common organic biocide, on its surface. To facilitate covalent attachment of TC on the membrane surface, TC was functionalized with amine moiety to prepare aminopropyl TC. Then, the TC-immobilized TFC (TFC-TC) membranes were fabricated through a one-step amide formation reaction between amine groups of aminopropyl TC and acyl chloride groups present on the PA membrane surface, which was confirmed by high-resolution XPS. Strong stability of the immobilized TC was also confirmed by a hydraulic washing test. Although the TFC-TC membrane showed slightly reduced separation performance compared to the pristine control, it still maintained a satisfactory RO performance level. Importantly, the TFC-TC membrane exhibited excellent antibacterial activity against both gram negative (<I>E. coli</I> and <I>P. aeruginosa</I>) and gram positive (<I>S. aureus</I>) bacteria along with greatly enhanced resistance to biofilm formation. Our immobilization approach offers a robust and relatively benign strategy to control biofouling of functional surfaces, films and membranes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Triclosan (TC), an organic biocide, is chemically immobilized onto TFC membranes. </LI> <LI> TC-immobilized membranes (TFC-TC) have high reverse osmosis separation performance. </LI> <LI> TFC-TC membranes exhibit strong and wide-spectrum antibacterial activity. </LI> <LI> TFC-TC membranes greatly enhance resistance to biofilm formation (biofouling). </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>