Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2013. / Cataloged from PDF version of thesis. / Includes bibliographical references. / The conductive polymer poly(3,4-ethylenedioxythiophene), (PEDOT), deposited via oxidative chemical vapor deposition (oCVD) has been investigated for use in organic electronic devices. The oCVD process as well as the application of oCVD PEDOT in photovoltaic devices is described. oCVD enables the synthesis of conjugated conductive films with advantageous properties for organic optoelectronic device applications. The oCVD process of forming the polymer film allows compatibility with a wide range of substrates, including those that are flexible or fragile, and provides a relatively low-energy means of depositing film layers that may not be possible through solution or other processing. Films deposited using varying oCVD process and pre- and post-treatment parameters (e.g. temperature, oxidant exposure, rinsing) were characterized based on their physical and electrical properties. It was found that acid rinsing of the already deposited films led to lower sheet resistance and surface roughness and an improvement in film stability. The oCVD PEDOT has been demonstrated as a replacement for solution-processed PEDOT:PSS as a hole transporting layer as well as for the transparent electrode material (typically ITO) in typical organic photovoltaic structures. Reverse-structure photovoltaic cells were also created using direct deposition of PEDOT electrodes onto small molecule active layer materials yielding fully dry-processed devices. The direct deposition of PEDOT top electrodes has enabled the fabrication of devices on opaque substrates leading to a greater than ten-fold improvement in previous devices fabricated on paper. Compatibility with novel photovoltaic materials has been demonstrated in work done using oCVD PEDOT as HTLs on graphene electrodes to make ITO-free devices. / by Rachel M. Howden. / Ph.D.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemical Engineering, 2015. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 199-218). / Shrinking sensors to the nanoscale introduces novel selectivity mechanisms and enables the ultimate sensitivity limit, single-molecule detection. Single-walled carbon nanotubes, with a bright fluorescence signal and no photobleaching, are a platform for implantable near-IR sensors capable of selectively detecting a range of small-molecules including the radical signalling molecule nitric oxide, the hormone estradiol, and sugars such as glucose. Selectivity is achieved by engineering an adsorbed phase of polymers, DNA, or surfactants at the nanotube/solution interface. Understanding these sensors requires a range of modeling and simulation tools and presents a unique opportunity to learn how these phases interact with small molecules. This thesis work discusses methods and limits to integrating data from many noisy stochastic sensors, show how these sensors can be used to monitor nitric oxide inside cells with unprecedented spatiotemporal resolution, and describes what is needed to engineer a selective adsorbed phase. In addition, another method of stochastic detection is described based on the stochastic ionic pore-blocking of transport inside individual single-walled carbon nanotubes. We discuss the current state-of-the-art for making and analysing devices with a single nanometer-scale pore, which necessarily leads to stochastic transport fluctuations. We also present work on the analysis on many devices with single characterized SWCNT pores. A maximum in transport rates inside SWCNTs with diameters of approximately 1.6 nm is shown and discussed, with implications for how we model transport at this scale and the design of new SWCNT membranes. Finally, we discuss how complex surfaces of interconnected nanoscale structures could lead to new materials with interesting mechanical properties. One example of such a structure is an interlocking sheet of graphene rings, analogous to macroscopic chainmail. Such a sheet would have interesting properties, as entropic out-of-plane fluctuations would lead to a negative Poisson's ratio, known as an auxetic material. We present simulations for what the properties of a sheet might look like. In addition, we present simulations for how these properties change as a membrane is strained and showing the conditions over which these surfaces have desirable properties. These results offer a path towards materials with tunable auxetic properties. / by Zachary Ward Ulissi. / Ph. D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2004. / Includes bibliographical references. / Microwave heating is an important technology that has been hampered in application by difficulties in measuring temperatures and temperature distributions during the microwave heating process. This thesis describes the development of a 3D imaging fluorescence thermometry system that was used to examine temporal and spatial variations in temperature within various aqueous solutions during their heating by microwave irradiation. The work provides one of the first experimentally-determined temperature maps for a system undergoing microwave heating. A 3D thermometry instrument was built based on the principles of Planar Laser Induced Fluorescence (PLIF) imaging. Temperatures were optically determined from ratiometric measurements of the fluorescence from a pair of molecular probes. A Dextran polymer labeled with Rhodamine B was used as a temperature-sensitive probe that operates between 20 and 60 ⁰C. A second temperature-insensitive probe, Rhodamine 110, was used to monitor changes in the laser emission intensity. A dual camera fluorescence detector system was employed to capture a 2D x-y plane at a specified z-axis position. A dichroic mirror and optical filters were used to separate the fluorescence signals from the two probes. The instrument was able to achieve a spatial resolution of 0.2 mm in x-y plane, a 5 mm spatial resolution in z-axis, and a temperature resolution of ±1.6 ⁰C. The 3D imaging thermometry instrument was modified for investigations into microwave heating. A microwave plasma applicator was adapted for heating experiments with water and salt solutions at concentrations ranging from 0-0.5 M. / (cont.) heating with reduced convective flows. The dynamics of microwave heating were captured in images with a 0.5 second interval. Microwave heating was observed at node positions in the microwave cavity and varied with the dielectric properties of the heated medium. The experimental results for initial heating were successfully modeled by 2D calculations of the electric field in the microwave cavity. 3D experiments were performed on both pure water sample and on a 0.1 M salt solution. Due to the rapid rate of microwave heating, the 3D experiments were conducted by repeating experiments at different positions in the microwave cavity under the same starting conditions and heating profiles. The simulations of the 2D electric fields in the microwave cavity suggest that the electric field intensity varied little across the z-axis positions. Experiments at different z-axis positions in the cavity had identical profiles within the error of the experiments. / by Timothy M. Finegan. / Ph.D.

Thesis (Sc.D.) Massachusetts Institute of Technology. Dept. of Chemical Engineering, 1948. / Vita. / Bibliography: leaves 431-437. / by James Neal Addoms. / Sc.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2006. / Vita. / Includes bibliographical references (leaves 128-137). / T cells are activated by recognition of foreign peptides displayed on the surface of antigen presenting cells (APCs), an event that triggers assembly of a complex microscale structure at the T cell-APC interface known as the immunological synapse (IS). It remains unresolved whether the unique physical structure of the synapse itself impacts the functional response of T cells, independent of the quantity and quality of ligands encountered by the T cell. As a first step toward addressing this question, we fabricated multicomponent protein surfaces that surrogate the role of APCs and studied T cell responses as a function of synapse structure. To pattern multiple proteins on surfaces, we synthesized and characterized a new polymer, poly(o-ntrobenzyl methacrylate-r-methyl methacrylate-poly(ethylene glycol) methacrylate (PNMP), a photoresist that can be processed under mild aqueous conditions. Based on the pH- and temperature-sensitive solubility of UV-exposed PNMP random terpolymers in aqueous buffers, two-component protein patterning was achieved under conditions that avoid exposing proteins to conditions outside the narrow range of physiological pH, ionic strength, and temperature where their stability is greatest. / (cont.) Using a photolithographic strategy we developed employing this novel PNMP photoresist polymer, we created multicomponent protein surfaces presenting micron-scale arrays of tethered T cell receptor (TCR) ligands (anti-CD3 'activation sites') surrounded by a field of tethered intercellular adhesion molecule-I (ICAM-1), as a model substrate on which T cells could be seeded to mimic T cell-APC interactions. CD4+ T cells seeded on these surfaces polarized and migrated; on contact with activation sites, T cells assembled an IS with a structure modulated by the physical pattern of ligand encountered. On surfaces patterned with focal spots of TCR ligand, T cells stably interacted with activation sites, proliferated, and secreted cytokines. In contrast, T cells interacting with activation sites patterned to preclude centralized clustering of TCR ligand failed to form stable contacts with activation sites, exhibited aberrant PKC-[Theta] clustering in a fraction of cells, and had significantly reduced production of interferon-[gamma]. These results suggest that focal clustering of TCR ligand characteristic of the 'mature' IS may be required under some conditions for full T cell activation. / by Junsang Doh. / Ph.D.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemical Engineering, 2015. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 293-306). / Systems of engineering interest usually evolve in time. Models that capture this dynamic behavior can more accurately describe the system. Dynamic models are especially important in the chemical, oil and gas, and pharmaceutical industries, where processes are intrinsically dynamic, or taking into account dynamic behavior is critical for safety. Especially where safety is concerned, uncertainty in the inputs to these models must be addressed. The problems of forward reachability and robust design provide information about a dynamic system when uncertainty is present. This thesis develops theory and numerical methods for approaching the problems of reachability and robust design applied to dynamic systems. The main assumption is that the models of interest are initial value problems (IVPs) in ordinary differential equations (ODEs). In the case of reachability analysis, the focus is on efficiently calculated enclosures or "bounds" of the reachable sets, since one motivating application is to (deterministic) global dynamic optimization, which requires such information. The theoretical approach taken is inspired by the theory of differential inequalities, which leads to methods which require the solution of an auxiliary IVP defined by parametric optimization problems. Major contributions of this work include methods and theory for efficiently estimating and handling these auxiliary problems. Along these lines, a method for constructing affine relaxations with special parametric properties is developed. The methods for calculating bounds also are extended to a method for calculating affine relaxations of the solutions of IVPs in parametric ODEs. Further, the problem of ODEs with linear programs embedded is analyzed. This formulation has further application to dynamic flux balance models, which can apply to bioreactors. These models have properties that can make them difficult to handle numerically, and this thesis provides the first rigorous analysis of this problem as well as a very efficient numerical method for the solution of dynamic flux balance models. The approach taken to robust design is inspired by design centering and, more generally, generalized semi-infinite programming. Theoretical results for reformulating generalized semi-infinite programs are proposed and discussed. This discussion leads to a method for robust design that has clear numerical benefits over others when the system of interest is dynamic in nature. One major benefit is that much of the computational effort can be performed by established commercial software for global optimization. Another method which has a simple implementation in the context of branch and bound is also developed. / by Stuart Maxwell Harwood. / Ph. D.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1920. / Includes bibliographical references (leaf 35). / by Walter G. Whitman. / M.S.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2002. / Includes bibliographical references. / Despite recent progress in materials synthesis, there are few materials with narrow pore size distributions and well-defined pore structures in the size range of 100 - 500 A. Materials with pores of 100 - 500 A possess a potential combination of high surface areas and pore sizes accommodating of large molecules that could make them of great use in the catalysis and separation of complex molecules important to the fine chemicals and pharmaceuticals industries. We have synthesized mesocellular silica foams (MCF) by using triblock copolymer (PEO-PPO-PEO, Pluronic) micelles to template the formation of silica from tetraethoxysilane precursors. The combination of the polymer amphiphile with a hydrophobic swelling agent (such as trimethylbenzene) resulted in larger pore sizes and more open pore structures than had previously been obtained with surfactant templates. The MCF materials have pore sizes of up to 350A, void fractions of > 0.85 and surface areas of - 700 m2/g. The basic properties of the swollen triblock copolymer micelles were investigated to provide a better understanding of their templating behavior. Small-angle neutron scattering (SANS) in conjunction with a thermodynamic model for swollen micelle formation were used to determine the size, shape and internal structure of the Pluronic micelles. Knowledge of the micelle structure and aggregation behavior was used to investigate the effects of changing polymer and oil types on the size of the swollen micelles and therefore to select the best systems for templating large pores in silica sol-gels. / (cont.) Synthesis experiments revealed that when tetraethoxysilane was added to micellar solutions containing only small amounts of oil, SBA-15 materials consisting of cylindrical pores packed in hexagonal arrays were formed. At an oil-to-polymer mass ratio of - 0.2, MCF (consisting of spherical cells connected by windows) was produced. We determined that the silica structures form as a result of the silica-induced precipitation of a polymer/silica rich phase. We have found two key factors in determining the pore size and structure of Pluronic-templated silica materials that were not previously well understood. First, there must be sufficient silica present in solution to precipitate the polymer aggregates. Second, it is the equilibrium structure of the concentrated precipitate, not the original solution, that determines the pore structure of the final material. To demonstrate the utility of the MCF materials, we have used MCF as a catalyst support for two different reactions: the Heck reaction and asymmetric hydrogenation. Palladium metal clusters were vapor-grafted onto MCF and several other large-pore silicas to generate active Heck catalysts. The activites of the "Pd-TMS" catalysts were equal to those of the best homogeneous organometallic catalysts reported in the literature. At 160ʻC, the activity of the MCF-supported catalyst was also better than that of catalysts supported on other mesoporous silicas. The high activity of the MCF-supported catalyst was attributed to its large pores and open pore structure, which reduced pore diffusion limitations on the reaction rate ... / by John Stangland Lettow. / Ph.D.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1999. / Includes bibliographical references (p. 379-399). / by Sandeep A. Patel. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2006. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Includes bibliographical references (p. 249-264). / This thesis focuses on two research areas that are particularly relevant to the practical application of surfactant science: (1) the micellization of multicomponent surfactant mixtures, and (2) the micellization of pH-sensitive (or amphoteric) surfactants. Surfactant formulations of practical utility typically consist of many surfactant components. In many practical applications, pH-sensitive surfactants are added as a secondary surfactant because they enhance performance properties, including solubility, foaming, and mildness to the skin or to the eyes. In addition, pH-sensitive surfactants may be used eectively in novel applications where pH variations can be utilized to control self-assembly, including controlled drug release, targeted gene delivery, and the fabrication of nanoscale materials for optics, electronics, and sensors. First, a molecular-thermodynamic (MT) theory was developed to account for counterion binding to mixed micelles composed of ionic-nonionic and ionic-zwitterionic binary surfactant mixtures. The theory successfully predicted the degree of counterion binding ([beta]) of monovalent and multivalent ions to mixed micelles as a function of the micelle composition ([alpha]). / (cont.) The theory was also found to be consistent with the concept of critical counterion binding. An inection in the [beta vs. [alpha] curve was correlated to a micelle shape transition. Second, the MT theory was generalized to include pH eects in order to model the micellization of pH-sensitive surfactants. The theory was validated by comparing predictions of critical micelle concentrations (cmc's), micelle aggregation numbers, and micellar titration behavior to experimental data for alkyldimethylamine oxide surfactants, which are cationic in the protonated state (at low pH) and zwitterionic in the deprotonated state (at high pH). The MT theory qualitatively reproduced the minimum in the cmc and the maximum in the micelle aggregation number, which are both observed experimentally at intermediate pH values, resulting from the synergy between the two forms of the pH-sensitive surfactant in the micelle. This self-synergy, which was previously attributed by other researchers to the formation ofsurfactant-surfactant hydrogen bonds in the micelle, was rationalized instead in terms of electrostatic interactions operating between surfactants and bound counterions in the micelle. Very good quantitative agreement was obtained for the predicted cmc's in solutions containing no added salt. / (cont.) In particular, the experimentally observed maximum in the cmc, which originated from changes in the solution ionic strength, was reproduced by the MT theory but not by the empirical regular solution theory (RST). Micellar titration data were also examined in terms of the relative values of the micellar deprotonation equilibrium parameter (pK). The pK was related to the derivative of the electrostatic contribution to the free energy of micellization ( gelec) with respect to . The molecular model of gelec predicted pK > 0 in the limit of micelles composed entirely of the deprotonated form of the pH-sensitive surfactant, consistent with the experimental data. Third, a theory based on RST was developed to model the titration behavior of micelles containing a pH-sensitive surfactant and an arbitrary number of conventional surfactants. The conventional surfactants were successfully modeled as a single eective surfactant, thus considerably simplifying the theoretical analysis of multicomponent surfactant mixtures. The RST description was validated using experimental micellar titration data for single surfactant systems (obtained from the literature) and for binary surfactant mixtures (measured as part of this thesis). / (cont.) Experimental uncertainties in the micellar titration data were examined, and a new method was introduced to account for these uncertainties by using a weighted regression analysis. Fourth, a MT theory was developed to model the micellization of mixtures containing an arbitrary number of conventional surfactants. The maximum micelle radius was examined theoretically for a ternary surfactant mixture. Due to the limited availability of experimental data, only the predicted cmc's were compared with the experimental cmc's. Good agreement was obtained for the predicted cmc's, which were comparable to, and sometimes better than, the cmc's determined using RST. The MT theory was also used to model a commercial nonionic surfactant (Genapol UD-079), which was modeled as a mixture of 16 surfactant components. The predicted cmc agreed remarkably well with the experimental cmc. The monomer concentration was predicted to increase signicantly above the cmc. In addition, the monomer and the micelle compositions were predicted to vary signicantly with surfactant concentration. These composition variations were rationalized in terms of competing steric and entropic eects and a micelle shape transition near the cmc. / (cont.) Finally, the MT theory was further generalized to model the micellization behavior of mixtures of a pH-sensitive surfactant and an arbitrary number of conventional surfactants. Predicted values of the solution pH of mixtures of a pH-sensitive surfactant and an ionic surfactant, as well as of the cmc's of mixtures of two pH-sensitive surfactants, compared favorably with the experimental values. The MT theory was also validated using micellar titration data for varying compositions of mixed micelles containing dodecyldimethylamine oxide (C12DAO) and a cationic, nonionic, or anionic surfactant. The MT theory accurately modeled the titration behavior of C12DAO mixed with the nonionic surfactant. However, C12DAO appeared to interact more favorably with the anionic and the cationic surfactants than waspredicted by the MT theory. The MT theories presented in this thesis represent the rst molecular-based models of the micellization behavior of the following systems: (1) pH-sensitive surfactants, (2) mixtures of three or more conventional surfactants, and (3) mixtures of pH-sensitive surfactants and conventional surfactants. The MT theories resulted in qualitative and quantitative predictions of the micellization properties for a variety of surfactant systems. / (cont.) A simpler theory based on RST was also developed to model titrations of micelles containing pH-sensitive and conventional surfactants. In addition, this thesis resulted in the rst experimental study of the eect of micelle composition on the titration behavior of mixed micelles containing a pH-sensitive surfactant and a conventional surfactant. The resulting MT theories have provided fundamental, physical insight, and they may also decrease the need for the costly and time-consuming process associated with "trial-and-error" surfactant formulation. / by Arthur Clayton Goldsipe. / Ph.D.