Browsing by Author "Chipara, Alin Cristian"

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    Compression induced stiffening and alignment of liquid crystal elastomers
    (2016-02-16) Verduzco, Rafael; Agrawal, Aditya; Chipara, Alin Cristian; Rice University; United States Patent and Trademark Office
    In some embodiments, the present disclosure provides methods of strengthening liquid crystal elastomers. In some embodiments, such methods include a step of placing the liquid crystal elastomer in an environment that applies dynamic stress to the liquid crystal elastomer. In further embodiments, the methods of the present disclosure also include a step of providing liquid crystal elastomers for placement in an environment that applies dynamic stress. In some embodiments, the liquid crystal elastomer is in a nematic phase before or during the application of dynamic stress. In some embodiments, the application of dynamic stress enhances the stiffness of the liquid crystal elastomer by more than about 10%. Further embodiments of the present disclosure pertain to liquid crystal elastomers that are made by the methods of the present disclosure.
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    Interface-Engineered Solid-Liquid Polymer Systems
    (2017-04-20) Chipara, Alin Cristian; Ajayan, Pulickel M.
    This thesis explores the optimization and design of novel materials by engineering interfaces to impart novel mechanisms to polymer composites and multi-phase materials. By taking advantage of chemical and mechanical interactions it is possible to create materials with novel properties and unique mechanisms such as self-stiffening, self-healing, and adhesion. These properties arise due to large electronegativity differences which are repeated throughout the polymer chains which in turn give rise to strong macroscopic effects. The addition of a dynamic interface, an interface which can move and adapt under varying stress conditions, further enhances the unique properties of these materials. The composites discussed in this thesis were synthesized using a variety of techniques including thermal sonication/chemical synthesis, and mechanical synthesis. These novel composites were characterized using a myriad of techniques such as dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray computerized tomography (CT), in-situ scanning electron microscopy-based (SEM) mechanical testing, tensile testing (ADMET frame), SEM, transmission electron microscopy (TEM), contact angle (CA), optical microscopy, and qualitative testing.