Bulletin of the American Physical Society
APS March Meeting 2013
Volume 58, Number 1
Monday–Friday, March 18–22, 2013; Baltimore, Maryland
Session W11: Invited Session: Polymer Based Soft Materials: Industrial Applications |
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Sponsoring Units: DPOLY FIAP Chair: Miriam Rafailovich, State University of New York, Stony Brook Room: 310 |
Thursday, March 21, 2013 2:30PM - 3:06PM |
W11.00001: Tuning the Photoinduced Motion of Glassy Azobenzene Polymers and Networks Invited Speaker: R.A. Vaia Continual innovation at the forefront of soft-matter, in areas such as liquid crystal networks, nano-composites and bio-molecules, is providing exciting opportunities to create smart materials systems that exhibit a controlled, reproducible and reversible modulation of physical properties. These material systems evoke the adaptivity of natural organisms, and inspire radical aerospace notions. A key example is photo-responsive polymers, which convert a light stimulus input into a mechanical output (work). Photoinduced conformational changes, such as within azobenzene, dictate molecular-level distortions that summate into a macroscopic strain, which often manifests as a shape change or motion. The transduction of the molecular-level response to a macroscale effect is regulated by mesoscopic features, such as chain packing, free volume, and local molecular order - factors which depend on chemical composition as well as the process history of the material. For example, physical aging increases the density of the glass, reduces local free volume, and thus decreases the minima in local conformation space which strongly influences the azobenzene photochemistry (trans-cis-trans isomerization). The subsequent change in the energy landscape of the system reduces the fraction of azobenzene able to undergo reconfiguration as well as increases the probability that those photoinduced conformations will relax back to the initial local environment. The result is a tuning of the magnitude of macroscopic strain and the ability to shift from shape fixing to shape recovery, respectively. [Preview Abstract] |
Thursday, March 21, 2013 3:06PM - 3:42PM |
W11.00002: Using Modeling to Design new Rheology Modifiers for Paints Invited Speaker: Valeriy Ginzburg Since their invention in 1970-s, hydrophobically ethoxylated urethanes (HEUR) have been actively used as rheology modifiers for paints. Thermodynamic and rheological behavior of HEUR molecules in aqueous solutions is now very well understood and is based on the concept of transient network (TN), where the association of hydrophobic groups into networks of flower micelles causes viscosity to increase dramatically as function of polymer concentration. The behavior of complex mixtures containing water, HEUR, and latex (``binder'') particles, however, is understood less well, even though it has utmost importance in the paint formulation design. In this talk, we discuss how the adsorption of HEUR chains onto latex particles results in formation of complex viscoelastic networks with temporary bridges between particles. We then utilize Self-Consistent Field Theory (SCFT) model to compute effective adsorption isotherms (thickener-on-latex) and develop a rheological theory describing steady-shear viscosity of such mixtures. The model is able to qualitatively describe many important features of the water/latex/HEUR mixtures, such as strong shear thinning. The proposed approach could potentially lead to the design of new HEUR structures with improved rheological performance. [Preview Abstract] |
Thursday, March 21, 2013 3:42PM - 4:18PM |
W11.00003: Particles against Reactive Oxygen Species for Sun Protective products Invited Speaker: Wilson Lee |
Thursday, March 21, 2013 4:18PM - 4:54PM |
W11.00004: Starch Applications for Delivery Systems Invited Speaker: Jason Li Starch is one of the most abundant and economical renewable biopolymers in nature. Starch molecules are high molecular weight polymers of D-glucose linked by $\alpha $-(1,4) and $\alpha $-(1,6) glycosidic bonds, forming linear (amylose) and branched (amylopectin) structures. Octenyl succinic anhydride modified starches (OSA-starch) are designed by carefully choosing a proper starch source, path and degree of modification. This enables emulsion and micro-encapsulation delivery systems for oil based flavors, micronutrients, fragrance, and pharmaceutical actives. A large percentage of flavors are encapsulated by spray drying in today's industry due to its high throughput. However, spray drying encapsulation faces constant challenges with retention of volatile compounds, oxidation of sensitive compound, and manufacturing yield. Specialty OSA-starches were developed suitable for the complex dynamics in spray drying and to provide high encapsulation efficiency and high microcapsule quality. The OSA starch surface activity, low viscosity and film forming capability contribute to high volatile retention and low active oxidation. OSA starches exhibit superior performance, especially in high solids and high oil load encapsulations compared with other hydrocolloids. [Preview Abstract] |
Thursday, March 21, 2013 4:54PM - 5:30PM |
W11.00005: New Developments in Brominated and Halogen-Free Flame Retardants Invited Speaker: A. Desikan With a broad portfolio of brominated, organophosphorus and inorganic flame retardants, ICL Industrial Products (ICL-IP) is engaged in the development of new flame retardants by exploiting the synergism between bromine based, phosphorus based and other halogen-free flame retardants. ICL-IP is also focusing on the development of polymeric and reactive flame retardants. This presentation will give examples of existing and new polymeric and reactive products for applications in thermoplastics, thermosets and polyurethane foam. This presentation will also show examples of phosphorus-bromine synergism allowing partial or complete elimination of antimony trioxide in many thermoplastics for electronic applications. New synergistic combinations of magnesium hydroxide with phosphorus and other halogen-free FRs will be presented. [Preview Abstract] |
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