Browsing by Author "Cue, John Michael O."
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Item Halide-Free Neodymium Phosphate Based Catalyst for Highly cis-1,4 Selective Polymerization of Dienes(Royal Soc Chemistry, 2019-01-24) Ren, Yixin; Miller, Justin T.; Polderman, Stefanie T.; Vo, Trinh D.; Wallace, Adele C. M.; Cue, John Michael O.; Tran, Sarah T.; Biewer, Michael C.; Stefan, Mihaela C.; 0000-0001-5374-8600 (Stefan, MC); Ren, Yixin; Miller, Justin T.; Polderman, Stefanie T.; Vo, Trinh D.; Wallace, Adele C. M.; Cue, John Michael O.; Tran, Sarah T.; Biewer, Michael C.; Stefan, Mihaela C.Neodymium-based Ziegler-Natta type catalytic systems are known to produce polydienes with high cis-1,4 content. It is generally believed that in Ziegler-Natta catalytic systems, a halide or pseudohalide, whether in the catalyst itself or a separate source, is required for the success of the polymerization. In this work, we have synthesized an unusual halide-free neodymium diethyl phosphate catalyst for diene polymerization. This neodymium complex combined with triisobutylaluminum (TIBA), formed a binary catalytic system and was used to polymerize β-myrcene. The catalytic system displays high stereospecificity and produces poly(β-myrcene) with 96% cis-1,4 content and a relatively narrow molecular weight distribution (Mᵥᵥ/Mₙ = 1.80). Also, kinetic studies indicated the catalytic system gives a pseudo-living polymerization. The block copolymer poly(β-myrcene)-b-poly(isoprene) was successfully synthesized by sequential monomer addition, further demonstrating the pseudo-living nature of polymerization with the neodymium diethyl phosphate catalyst.Item Molecularly-Engineered, 4D-Printed Liquid Crystal Elastomer Actuators(WILEY-VCH Verlag GmbH, 2018-11-27) Saed, Mohand O.; Ambulo, Cedric P.; Kim, Hyun; De, Rohit; Raval, Vyom; Searles, Kyle; Siddiqui, Danyal A.; Cue, John Michael O.; Stefan, Mihaela C.; Shankar, M. Ravi; Ware, Taylor H.; 0000-0001-5154-6378 (Saed MO); 0000-0001-7996-7393 (Ware, TH); Saed, Mohand O.; Ambulo, Cedric P.; Kim, Hyun; De, Rohit; Raval, Vyom; Searles, Kyle; Siddiqui, Danyal A.; Cue, John Michael O.; Stefan, Mihaela C.; Ware, Taylor H.Three-dimensional structures that undergo reversible shape changes in response to mild stimuli enable a wide range of smart devices, such as soft robots or implantable medical devices. Herein, a dual thiol-ene reaction scheme is used to synthesize a class of liquid crystal (LC) elastomers that can be 3D printed into complex shapes and subsequently undergo controlled shape change. Through controlling the phase transition temperature of polymerizable LC inks, morphing 3D structures with tunable actuation temperature (28 ± 2 to 105 ± 1 °C) are fabricated. Finally, multiple LC inks are 3D printed into single structures to allow for the production of untethered, thermo-responsive structures that sequentially and reversibly undergo multiple shape changes.