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Park, Jeyoung,Seo, Myungeun,Choi, Hyungsam,Kim, Sang Youl Royal Society of Chemistry 2011 Polymer chemistry Vol.2 No.5
<P>A series of well-defined poly(arylene ether sulfone)s were synthesized (1P–4P) by chain-growth condensation polymerization with amide initiators having various numbers of initiating sites. Differential Scanning Calorimetry (DSC) study of the polymers revealed that branched polymers (3P and 4P) had higher glass transition temperatures (<I>T</I><SUB>g</SUB>) than linear polymers (1P and 2P) when they had the identical concentration of end groups. However, the viscosity of the polymers decreases as the number of branches increase due to the change of the hydrodynamic volume. Interestingly physical gelation of THF solution of these polymers was observed. Analyses of the self-assembled structure by FE-SEM, FE-TEM, temperature-dependent <SUP>1</SUP>H NMR, FT-IR, and XRD indicated that the formation of fibrillar network was driven by the hydrogen bonding of aromatic amides.</P> <P>Graphic Abstract</P><P>Synthesis of poly(arylene ether sulfone)s with various numbers of arms by chain-growth polycondensation and physical gelation induced by self-assembly. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c0py00418a'> </P>
Preparation of Self-Healing Polymers by Controlling Hydrogen Bond Array
Jeyoung Park(박제영) 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.2
An important issue for intrinsic self-healing polymers is breaking the trade-off between mechanical properties and healing efficiency at ambient temperatures. Self-healing properties were investigated by designing asymmetric hydrogen bond array to various polymer materials including thermoplastic elastomers, vitrimers, and hydrogels. For example, a carbonate-type thermoplastic polyurethane exhibits a tensile strength of 43 MPa and self-heals at 35 °C; a robust bio-based supramolecular polymer recovered its original strength after 1 min at room temperature; and a malleable and stretchable poly(vinyl alcohol)-borax hydrogel embedded with free micelles was synthesized. In addition, applications of self-healing polymers such as time-temperature indicator, healthcare monitoring sensor, and transdermal patch were demonstrated.
Park, Jeyoung,Kim, Jisung,Seo, Myungeun,Lee, Jinhee,Kim, Sang Youl The Royal Society of Chemistry 2012 Chemical communications Vol.48 No.85
<P>A new class of fluorescent organogelators, pyrene-containing poly(arylene ether sulfone)s, showed two fluorescence switching modes in different gelation solvents. The THF gel exhibited excimer emission due to dimerization of the pyrene groups. In contrast, excimer emission was quenched after gelation in MC because of stacking among the pyrene groups.</P> <P>Graphic Abstract</P><P>Fan-shaped polymers showed two different gelation-induced fluorescence switching modes. The gel formed in the THF solution exhibited excimer emission, while the emission of pyrene excimer was quenched after gelation in MC. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2cc35804b'> </P>