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Lee, Jeongwook,Chang, Kyeol,Kim, Sunhye,Gite, Vikas,Chung, Hoeil,Sohn, Daewon American Chemical Society 2016 Macromolecules Vol.49 No.19
<P>Metal complexation-based gelation imparts load-bearing hydrogels with striking properties like reversibility, self-healing, and mechanical tunability. Using a bio-inspired metal catechol complex, these properties have been introduced to a variety of polymer hydrogels, except hyaluronic acid, which is widely used in biological applications. In this research, we developed two different hyaluronic acid (HA) hydrogels by regulating the gelation kinetics of Fe3+ and a catechol cross-linker, including Fe3+-induced covalent bonding and coordination bonding. Dual roles of Fe3+ in catechol-modified HA (HA-CA), Fe3+ catechol coordination, and catechol oxidation followed by a coupling reaction were selectively applied for different gelations. Phase-changeable HA-CA gel was attributed to dominant Fe3+ catechol coordination with immediate pH control. Alternatively, allowing a curing time to form catechol coupling bonds resulted in color-changeable HA-CA gels with pH control. The gel structure is then preserved by dual cross-linking through covalent catechol-coupling-based coordinate bonds and electrostatic interactions between Fe3+ and HA-CA. The hydrogels showed enhanced cohesiveness and shock-absorbing properties with increasing pH due to coordinate bonds inspired by marine mussel cuticles. The present gelation strategy is expected to expand the utility of HA hydrogels in biological applications, offering easy control over the phase, gel network, and visco elastic properties.</P>
Prakash Alagi,Ravindra Ghorpade,장정현,Chandrashekhar Patil,Harishchandra Jirimali,Vikas Gite,홍성철 한국고분자학회 2018 Macromolecular Research Vol.26 No.8
One of the major challenges in current polymer industry is to develop renewable and sustainable alternatives to petroleum-based raw materials. In this study, soybean oil (SO) was adopted as a renewable resource to afford polyols (MSO) with predetermined primary hydroxyl values (OHVs). The MSOs were prepared through a simple thiol-ene click reaction between the SO and 2-mercaptoethanol. The OHVs of the MSOs were adjusted simply by controlling the conversion of carbon-carbon double bonds of SO to OH groups. To explore their potential applications, series of polyurethane (PU) coatings were prepared from the MSOs. The MSOs with increased OHVs afforded PU coatings with higher glass transition temperature and improved adhesion strength values. Notably, increased OHVs of MSOs afforded PU coatings with improved anticorrosion properties in 3.5 wt% NaCl corrosive medium, which was attributed to the strong adhesion and blocking characteristics of the PU coatings. This study demonstrated that the number of hydroxyl functionality of the bio-based polyols played a crucial role in controlling the characteristics of the PU coatings.