Bulletin of the American Physical Society
APS March Meeting 2015
Volume 60, Number 1
Monday–Friday, March 2–6, 2015; San Antonio, Texas
Session W41: Polymer Nanocomposites II |
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Sponsoring Units: DPOLY Chair: Shengfeng Cheng, Virginia Polytechnic Institute and State University Room: 214A |
Thursday, March 5, 2015 2:30PM - 2:42PM |
W41.00001: Liquid crystal self-assembly of zirconium phosphate nanosheet in polymeric matrix Xiayun Huang, Xuezhen Wang, Zhengdong Cheng The controlled assembly of nanomaterials requires them to be well-organized over large area with controlled orientation and density. Although progress has been achieved via Langmuir-Blodgett technique, electric field directed assembly, and flow-assisted alignment, it remains a challenge for the future to control the density and orientation, especially the anisotropic particle, in the polymeric matrix. Here, we investigate the controlled assembly via liquid crystal assembly of discotic $\alpha $-zirconium phosphate ($\alpha $-ZrP) aqueous suspension. Liquid crystal is the material with spontaneous orientation order and our group have shown the strong aspect ratio dependency of the isotropic-nematic transition of discotic $\alpha $-ZrP nanosheet suspension. These $\alpha $-ZrP discotic suspension exhibited the stable nematic alignment at low volume factions. When volume faction increases, it follows with the phase transition to sematic phase. Moreover, intrinsic high anisotropic nanosheet enables the formation of highly ordered liquid crystal orientation at much reduced concentration and the polymeric matrix brings the extra-functionalities, such as thermal, optical, electrical and mechanical properties. The liquid crystal phase orientation will remains in the polymeric matrix and the polymeric matrix serves as the interlayer spacer. The liquid crystal polymer nanocomposite was fabricated using high-aspect-ratio $\alpha $-ZrP nanosheet embedded into a polymeric network. Due to the hydrogen bonding interaction of hydroxyl group of $\alpha $-ZrP and polymeric matrix, liquid crystal nanocomposite has the interesting thermal-optical response. [Preview Abstract] |
Thursday, March 5, 2015 2:42PM - 2:54PM |
W41.00002: Raman, UV-Vis, and Wide Angle X-Ray Scattering Investigations on Polyvinylidene Fluoride -- Fe$_{3}$O$_{4}$ Nanocomposites Jerry Contreras, Ibrahim Elamin, Jason Parsons, Dorina M. Chipara, James Hinthorne, Karen Lozano, Mircea Chipara Fe$_{3}$O$_{4}$ nanoparticles of about 75 nm from Nanostructured {\&} Amorphous Materials, Inc. have been dispersed within the polyvinylidene fluoride (PVDF) by melt mixing. Nanocomposites with various weight fraction of nanofiller (0{\%}, 0.2 {\%}, 0.6 {\%}, 1.2{\%}, 2.4 {\%}, 5.8 {\%}, 12 {\%}, 23 {\%}, and 30 {\%} ) have been obtained and measured by Wide Angle X-Ray Scattering (WAXS, Bruker Discovery 8 with the Cu K$\alpha $ radiation), Raman spectroscopy (Bruker Senterra confocal Raman microscope operating at 785 nm), and UV-Vis. Raman spectra indicated that alpha PVDF is the main crystalline component of the polymeric matrix and revealed a fast decay of the polymeric lines as the loading with iron oxide is increased. The Raman lines have been successfully fitted by an extended Breit-Wigner Fano lineshape. The effect of the nanofiller on the position, amplitude, and width of Raman lines is analyzed in detail. WAXS investigations confirmed the presence of magnetite. The effect of the loading with nanoparticles on the position, amplitude, and width of WAXS lines of Fe$_{3}$O$_{4}$ and PVDF are reported. [Preview Abstract] |
Thursday, March 5, 2015 2:54PM - 3:06PM |
W41.00003: Synergistic templated self-assembly of cellulose nanocrystals in thin block copolymer films Danielle Grolman, Jeffrey Gilman, Chelsea Davis, Alamgir Karim Nanofillers in thin polymer films offer unique advantage to potentially modify the film's thermal, optical, electrical and mechanical properties due to the high surface area to volume ratio and intrinsic property change at the nanoscale. Nanofilled polymer films have been shown to exhibit unusual film stability to dewetting with a nonmonotonic behavior with nanofiller loading, potentially arising from factors such as competitive phase behavior and filler aggregation, particularly in the high nanofiller concentration limit. In this regard, block copolymer films can act as ideal nanoscale structured templates to selectively sequester and organize nanofillers. In conjunction with incorporated cellulose nanocrystals (CNCs), we seek to understand how individual anisotropic nanofillers can provide synergistic reinforcement to inherently anisotropic nanostructured block copolymer films. A clear enhancement in the Young's Modulus was observed with increased CNC loading using strain-induced elastic buckling instability for mechanical measurements (SIEBIMM) for thin films. To this end, we examine the nanoscale to microscale morphology of the blend film through AFM, TEM and grazing incidence small-angle x-ray scattering (GISAXS), and CNC dispersion and percolation through high-intensity grazing incidence wide-angle x-ray scattering (GIWAXS) analysis. [Preview Abstract] |
Thursday, March 5, 2015 3:06PM - 3:18PM |
W41.00004: Raman and Wide Angle X-Ray Studies on Polystyrene-Block Polyisoprene-Block Polystyrene - Graphene Nanocomposites Dorina Chipara, Oscar M. Guerrero, Alejandra Gonzalez, Brian Yust, Ibrahim Elamin, James Hinthorne, Mircea Chipara Nanocomposites have been obtained by loading a block copolymer Polystyrene-Block Polyisoprene-Block Polystyrene (PS-bPI-bPS), containing 17{\%} styrene (purchased from Sigma Aldrich) with various amounts of graphene nano platelets (HD Plas Grade 4), purchased from Cheap Tubes Inc., through the solution path: PS-bPI-bPS was dissolved within cyclohexane, then nanofiller was added and the mixture was sonicated for 1 h. The high power sonication (500 mW) improved the dispersion of the filler within the polymeric matrix. The homogenized solution was poured on glass slides covered by aluminum foil and left to evaporate the solvent. A final thermal treatment of the as obtained nanocomposites at 75 $^{\circ}$C, has been performed overnight, in an oven. Nanocomposites containing various weight fraction of fillers ranging between 0{\%} and 40{\%} have been obtained. The as obtained films have been investigated by Wide Angle X-Ray Scattering, using a Bruker Discovery 8 spectrometer, FTIR (Bruker Tensor 27), UV-Vis, and Raman spectroscopy, (using a Bruker Senterra, confocal Raman microscope operating at 785 nm). The dependence of these spectra originating from the polymeric matrix and from the filler on the loading with graphene is discussed. [Preview Abstract] |
Thursday, March 5, 2015 3:18PM - 3:30PM |
W41.00005: Computations Related to Nanoparticle Characterization and Nanocomposite Property Estimation Fernando Vargas-Lara, Ahmed Hassan, Edward Garboczi, Jack F. Douglas The macroscopic properties of high-performance bulk polymer composite materials derive from the properties of the microscopic building block component particles, the polymer matrix in which they are placed, and the state of particle dispersion. The rational design of new materials then requires the characterization of the polymer matrix and the individual particles, as well as an understanding of how particle properties change as a function of spatial dispersion and particle size polydispersity and shape fluctuations. To systematically explore this multi-dimensional parameter space, we combine molecular dynamic simulations, numerical path-integrations (ZENO) and finite element calculations (COMSOL). As a specific illustration of this computational path, we calculate the electric and magnetic polarizability tensor of carbon nanotubes and graphene sheets having complex morphologies. Knowing these basic particle properties, one then can estimate electromagnetic properties of nanocomposites made with these particles, i.e., conductivity [Preview Abstract] |
Thursday, March 5, 2015 3:30PM - 3:42PM |
W41.00006: Differential Scanning Calorimetry Investigations on Polyvinylidene Fluoride -- Fe$_{3}$O$_{4}$ Nanocomposites Samantha Salinas, Robert Jones, Dorina M. Chipara, Mircea Chipara Nanocomposites of polyvinylidene fluoride (PVDF)--magnetite (Fe$_{3}$O$_{4})$ with various weight fractions of nanofiller (0{\%}, 0.2 {\%}, 0.6 {\%}, 1.2{\%}, 2.4 {\%}, 5.8 {\%}, 12 {\%}, 23 {\%}, and 30 {\%} ) have been obtained via melt mixing by loading PVDF with Fe$_{3}$O$_{4}$ particles (average size 75 nm from Nanostructured {\&} Amorphous Materials, Inc). Thermal stability of PVDF-Fe$_{3}$O$_{4}$ has been investigated by TGA in nitrogen. The increase of the thermal stability of PVDF due to the loading with Fe$_{3}$O$_{4}$ was quantified by the shift of the temperature at which the (mass) degradation rate is maximum as a function of Fe$_{3}$O$_{4}$ content. The effect of the nanofiller on the crystallization of PVDF was investigated by isothermal DSC (TA Instruments, Q500). Non isothermal DSC tests, (at various heating rates ranging from 1 to 25 $^{\circ}$C/min) have been used to locate the glass, crystallization, and melting temperatures. The dependence of the glass, crystallization, and melting temperatures on the concentration of nanoparticles is reported and analyzed in detail. The data are critically analyzed within the classical Avrami theory. [Preview Abstract] |
(Author Not Attending)
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W41.00007: Characteristics of vinyl-ester and carbon fiber composite dry and wet probe by Positron Annihilation Lifetime Spectroscopy Mahmoud Madani, Richard D. Granata Carbon fiber composites of vinylester resins, Derakane 8084 and 510A, were studied dry and after water exposure. In this study, positron annihilation lifetime spectroscopy (PALS) was used to investigate the free volume fraction and the size of the free volume voids within the polymer matrix. The relative free volume (fractions replae by of positron lifetime intensities) in VE8084 polymer and in VE510A (Space) polymer were 35.2{\%} and 13.8{\%}, respectively. The free volume lifetime and intensities were determined as a function of the polymer thickness and significant differences were observed in both polymers with versus without post-curing. The effects of water uptake in these materials were also determined by PALS. Water uptake showed a 2{\%} change in intensity of the longer lifetime (1.85 ns) in VE8084 polymer and in VE510A about 1.8{\%}. The longer lifetime intensities in the wet composites were 17.1{\%} in the 8084 polymer and its carbon fiber composite and 7.1{\%} in the 510A polymer and its carbon fiber composite. For composite with 8084 polymer saturated (0.33{\%} water gain) with seawater at 40 or 60 $^{\circ}$C, no change in the longer lifetime intensity was observed which indicates no water entered the free volume voids (indicates replace by and ) some differences between composite and neat polymer. For 510A resin the third lifetime intensity dropped from 7.1{\%} to 3.9{\%} indicating 48{\%} of the free volume filled with water in the composite only after saturation with seawater with respect to dry one. [Preview Abstract] |
Thursday, March 5, 2015 3:54PM - 4:06PM |
W41.00008: Raman Spectroscopy of Poly-Urea Formaldehyde Microcapsules Omar Espino, Dorina Chipara, Mircea Chipara, Melissa Martinez The objective of this research project was to add self-healing capabilities to polymeric nanocomposites. We used the ``classical'' method to obtain self-healing polymers with the addition of TiO$_{2}$ nanoparticles in the self-healing system. Self-healing polymers are obtained by dispersion of first generation Grubbs catalysts and microcapsules filled with monomers (typically DCPD). These kind of ``smart materials'' are able to survive to high mechanical stress via the ignition of the so called ``autonomous self-healing mechanism'' which is actually a ring opening methatesis polymerization (ROMP) reaction triggered by mechanical stresses in excess over a threshold limit through the rupture of microcapsules and the release of the monomeric content. As a preliminary step for adding self-healing capabilities in nanocomposites, the synthesis of microcapsules filled with dicyclopentadiene (DCPD) is vital for the addition of self-healing capabilities to polymeric matrices. We synthesized polyurea-formaldehyde (PUF) microcapsules filled with monomer (DCPD) using the in-situ polymerization. The synthesis was monitored by Raman spectroscopy, optical microscopy, and pH measurements that has been extensively used as a non-invasive techniques in the characterization of polymers and monitoring of organic reactions. The goal of this research was to assess the formation of the microcapsules during synthesis and the presence of the DCPD in the microcapsules. Samples were taken during the synthesis every 30 minutes and analyzed by Raman spectroscopy, and optical microscopy keeping a control over the pH of the solution. [Preview Abstract] |
Thursday, March 5, 2015 4:06PM - 4:18PM |
W41.00009: Controlling the dispersion and configuration of nanofillers in electrically driven polymer jets with and without air flow Yevgen Zhmayev, Yong Joo, Jay Park, Ling Fei, Prabhleen Kaur, Hongshen Liu Controlling the dispersion of nanofillers in polymer matrices has a significant effect on their properties. Employing circumferentially uniform air flow through the sheath layer of the concentric coaxial nozzle, the gas-assisted electrospinning utilizes both high electric field and controlled air flow which can offer i) enhanced stretching of fluid jet and thus much higher throughput and thinner fibers, and ii) better control of dispersion and configuration of nanofillers in a polymer matrix even at high loadings. The ability to tailor the distribution of various nanofillers (1.85-12.92 vol. {\%} of spherical SiO$_{\mathrm{2\thinspace }}$and Si nanoparticles and rod/tube--like carbon nanotubes and carbon nanoribbons) in a polyvinyl alcohol (PVA) jet was demonstrated by varying electric potentials in conventional electrospinning and air flow rates in gas-assisted electrospinning. The distribution of nanofillers in nanofibers was measured by transmission electron microscopy (TEM), and analyzed using an image processing software to obtain concentration profiles. By increasing the electric potential in conventional electrospinning from 80 to 125 kV/m, we observed almost a twofold improvement in NP distribution. The further enhancement of nanoparticle dispersion was observed in gas-assisted electrospinning: Our analysis indicated an additional 70 percent improvement with the application of high, but controlled air flow. Lastly, the enhanced performance by the resulting nanofibers with controlled nanofiller dispersion will also be addressed in Li-ion battery anode applications. [Preview Abstract] |
Thursday, March 5, 2015 4:18PM - 4:30PM |
W41.00010: Flow Effect on Alignment of MWCNTs in Polymer Nanocomposites Mashael Alghamdi, Georgi Georgiev, Germano Iannacchione Polymer nanocomposites are grabbing attraction for their light weight, low cost, and enhanced characteristics. In this study, we present fabrication of polyethylene films embedded with multiwalled carbon nanotubes (MWCNTs) with anisotropic characteristics. A well dispersion of the MWCNTs in melt polyethylene is controlled through sonication to overcome their natural tendency to aggregate. An elongation process is demonstrated by free flowing on temperature- controlled surface in order to create organized long- range alignment of the nanoparticles within the host polymer matrix. The samples harvested off substrate after cooling down are of high anisotropy. Cross-polarized microscopy demonstrated that the polarization is directionally dependent and hence enhanced alignment in the flow direction. Therefore, they are expected to have orientation- dependent electrical, thermal, mechanical, and optical properties. Investigation conducted is on how flow rate, surface temperature, polymer molecular weight, concentration, and aspect ratio of MWCNTs affect the degree of polarization. The preliminary results show that they are extremely promising due to the possibility of creating nanocomposites with desired properties suit certain applications. [Preview Abstract] |
Thursday, March 5, 2015 4:30PM - 4:42PM |
W41.00011: Polymer Morphology and Crystallinity close to Inorganic Surfaces Kiriaki Chrissopoulou, Hellen Papananou, Spiros H. Anastasiadis, Konstantinos S. Andrikopoulos, George A. Voyiatzis Polymer behavior close to surfaces or when restricted in space can be very different from that in the bulk. In this work, we investigate the morphology, crystallization and chain conformation of a hydrophilic, semi-crystalline polymer, poly(ethylene oxide), PEO, when mixed with silica, SiO2, nanoparticles in a broad range of compositions. The good dispersion of the nanoparticles was verified by Transmission Electron Microscopy (TEM), whereas the morphology and crystallization behaviour of the hybrids were investigated with, X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC). A gradual decrease of polymer crystallinity with increasing nanoparticles content is observed; nevertheless, polymer crystallization exists for all silica loadings. Moreover, DSC showed two melting and crystallization transitions in hybrids with polymer content lower than 50wt\%, indicating that the polymer crystallizes differently than the bulk when it is in a thin interfacial layer near the silica surface. The existence of the two transitions are also evident in the IR and Raman spectra. Partially sponsored by EU (COST Action MP0902) and by the Greek GSRT (Research Funding Program: ARISTEIA II (SMART-SURF, project No. 3393, 2013SE01380048). [Preview Abstract] |
Thursday, March 5, 2015 4:42PM - 4:54PM |
W41.00012: The path to achieving molecular dispersion in an extremely dense reactive mixture Jigneshkumar Patel, Zou Xiang, Shaw Hsu, Andrew Schoch In any multicomponent reactive system, a uniform and continuous dispersion of reactants is necessary to achieve a complete reaction. In this study, we have examined the role of one additional component to disperse two seemingly unlikely reactants, including a highly crystalline hexamethylenetetramine (hexa) and strongly hydrogen bonded phenol formaldehyde resin. By combining information from NMR, infrared spectroscopy and differential scanning calorimetry, we were able to decipher the role of specific intermolecular interactions in order for this additional component to dissolve the highly crystalline hexa and to plasticize the phenol formaldehyde resin in this crosslinking reaction. It is clear that the presence of the third component increased the segmental mobility, disrupted the hydrogen bonded matrix, and freed the hydroxyl units, which further increased the solubility of hexa. Both the endothermic and exothermic transitions are accounted for in the calorimetric data obtained. For the first time, it is possible to understand the miscibility behavior of this multicomponent system. By designing the additional component to form a hydrogen bond with one or more N of the highly symmetric hexamethylenetetramine, it is then possible to obtain the effective molar ratio of each component needed to complete the crosslinking reaction efficiently. The understanding of this system is applicable to a broad range of reactive systems. [Preview Abstract] |
Thursday, March 5, 2015 4:54PM - 5:06PM |
W41.00013: Polymer/Pristine Graphene Based Composites: From Emulsions to Strong, Electrically Conducting Foams Steven Woltornist, Jan-Michael Carrillo, Thomas Xu, Andrey Dobrynin, Douglas Adamson The unique electrical, thermal and mechanical properties of graphene make it a perfect candidate for applications in graphene/graphite based polymer composites, yet challenges due to the lack of solubility of pristine graphene/graphite in water, common organic solvents, and polymer solutions and melts have limited its practical utilization. Here we report a scalable and environmentally friendly technique to form water-in-oil type emulsions stabilized by a graphitic skin consisting of overlapping pristine graphene sheets that enables the synthesis of open cell foams containing a continuous graphitic skin network. At the heart of our technique is the strong attraction of graphene to high-energy oil and water interfaces. This allows for the creation of stable water-in-oil emulsions with controlled droplet size and overlapping graphene sheets playing the role of surfactant by covering the droplet surface and stabilizing the interfaces with a thin graphitic skin. These emulsions are used as templates for the synthesis of the open cell foams with densities below 0.35 g/cm3 and exhibiting remarkable mechanical and electrical properties including compressive moduli up to $\sim$ 100 MPa, compressive strengths of over 8.3 MPa, and bulk conductivities approaching 7 S/m. [Preview Abstract] |
Thursday, March 5, 2015 5:06PM - 5:18PM |
W41.00014: Organic-Inorganic Shish-Kebabs: Nanocrystal Kebabs Periodically Assembled on Stretched Flexible Polymer Shish Zhiqun Lin, Hui Xu, Yuci Xu, Xinchang Pang, Yanjie He, Jaehan Jung, Haiping Xia We report an unconventional yet general strategy to craft an exciting variety of 1D necklace-like nanostructures comprising uniform functional nanodisks periodically assembled along a stretched flexible polymer chain by capitalizing on judiciously designed amphiphilic worm-like diblock copolymer as nanoreactors. These nanostructures can be regarded as organic-inorganic shish-kebabs, in which nanodisk kebabs periodically situated on a stretched polymer shish. Simulations based on self-consistent field theory reveal that the formation of organic-inorganic shish-kebabs is guided by the self-assembled elongated star-like diblock copolymer constituents constrained on the highly stretched polymer chain. [Preview Abstract] |
Thursday, March 5, 2015 5:18PM - 5:30PM |
W41.00015: Strain-Tunable One Dimensional Photonic Crystals Based on Zirconium Dioxide/Slide-Ring Elastomer Nanocomposites for Mechanochromic Sensing Irene Howell, Cheng Li, Nicholas Colella, Kohzo Ito, James Watkins Here we report on the fabrication and performance of tunable one dimensional photonic crystals (1DPCs) based on zirconium dioxide/Slide-Ring elastomer nanocomposites. 1DPCs, or Bragg mirrors, display a photonic stop band at specified wavelengths based on the design of their alternating high and low refractive index layers. By adjusting the weight percent of nanoparticles in the composite materials, a refractive index contrast of 0.18 can be achieved between filled and unfilled elastomer layers. The novel Slide-Ring matrix material consists of supramolecular polyrotaxane polyols, and maintains elasticity in the composite 1DPCs. Additionally, the high refractive index nanopartilces enable greater refractive index contrast when compared with purely polymer systems. Therefore we are able to demonstrate a 1DPC of just 6 periods, which maintains 40{\%} reflectance over strains up to 42{\%}. Due to their elastic and flexible behavior, these materials can function as colorimetric strain sensors. The applied strain results in a visible color shift from red to blue, demonstrating a tensile mechanochromic ($\Delta \lambda $/$\Delta \varepsilon $max) sensitivity as high as 6.05 nm/{\%}. [Preview Abstract] |
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