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Polymer nanocomposite (PNC) films are of interest for many applications including electronics, energy storage, and advanced coatings. In phase-separating PNCs, the interplay between thermodynamic and kinetic factors governs the assembly of polymer-grafted nanoparticles (NPs), which directly influences material properties. Understanding how processing parameters affect the structure-property relationship of PNCs is important for designing advanced materials. This thesis provides insight by investigating a model PNC system of poly(methyl methacrylate)-grafted nanoparticles (PMMA-NPs) embedded in a poly(styrene-ran-acrylonitrile) (SAN) matrix. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was developed to quantify the distribution of NPs within PMMA-NP/SAN films, enabling precise 3D reconstruction of PNC structures. Experimental parameters such as primary ion beam angle and charge compensation were optimized to enhance secondary ion signals and depth resolution. Upon annealing in the twophase region, PMMA-NP/SAN films exhibited phase separation and surface segregation, leading to morphological evolutions characterized by atomic force microscopy (AFM), ToF-SIMS, water contact angle measurements, and transmission electron microscopy. By systematically exploring the effects of film thickness on PNC structures, we found that film thickness-induced confinement reduces lateral phase separation and enhances NP dispersion at the surface. A dimensional crossover from three to two dimensions was observed around 240 nm, below which surface-directed spinodal decomposition is suppressed. As a result of phase separation and surface segregation, six distinct bulk morphologies were identified, allowing for the construction of a morphology map correlating film thickness and annealing time. Among these morphologies, percolated structures were found to improve mechanical properties such as hardness and reduced modulus, as measured using AFM nanoindentation. Notably, interconnected networks show the highest hardness and modulus at both low and high force loadings. Additionally, Marangoni-induced hexagonal honeycomb patterns were observed in spin-coated as-cast PMMA-NP/SAN films. By changing to a less volatile solvent, these defects were eliminated, demonstrating the importance of solvent selection in achieving uniform and high-quality thin films. These findings demonstrate the potential for precise control of surface-enriched and phase-separated microstructures in PNC films through tailoring processing conditions. This thesis advances the understanding of processing-structure-property relationships in PNCs, providing a foundation for designing highly functional materials with broad industrial applications. 

Polymer infiltration is studied in a bicontinuous, nanoporous gold (NPG) scaffold. For poly(2-vinylpyridine) (P2VP) with molecular weights (M_w) from 51k to 940k Da, infiltration is investigated in a NPG with fixed pore radius (R_p= 34 nm) under moderate confinement (Γ = R_g/R_p ) 0.18 to 0.78. The time for 80% infiltration (τ_(80%)) scales as M_w^1.43, similar to PS, but weaker than bulk behavior. Infiltration of P2VP is slower than PS due to stronger P2VP-wall interactions resulting in a physisorbed P2VP layer. This interpretation is supported by the similar scaling of τ_(80%) for P2VP and PS, as well as Molecular Dynamics (MD) simulations. Simulations show that infiltration time scales as M_w^1.43and that infiltration slows as the polymer-wall attraction increases. As M_w increases, the effective viscosity transitions from greater than to less than the bulk viscosity due to pore narrowing and a reduction entanglement density. These studies provide new insight for polymer behavior under confinement and a new route for preparing nanocomposites at high filler loadings. 

This study investigates Marangoni effect-induced structural changes in spin-coated polymer nanocomposite (PNC) films composed of poly(methyl methacrylate)-grafted silica nanoparticles (NPs) and poly(styrene-ran-acrylonitrile). Films cast from methyl isobutyl ketone (MIBK) solvent exhibit distinct hexagonal honeycomb cells with thickness gradients driven by surface tension variations. Atomic force microscopy reveals protruded ridges and junctions at cell intersections, where NP concentration is the highest. Upon annealing at 155 degrees C, NPs segregate to the surface due to their lower surface energy, and the initially protruding features flatten and eventually form depressed channels while maintaining higher NP density than surrounding areas. Time-of-flight secondary ion mass spectrometry corroborated these findings, highlighting enhanced surface segregation of NPs in MIBK films. These defects can be eliminated using methyl isoamyl ketone (MIAK) as a solvent that produces homogeneous films of uniform thickness. This study highlights the impact of the Marangoni effect on the microstructure and surface properties of PNC films, providing insights for enhancing film quality and performance. 

One of the biggest challenges in the field of polymer nanocomposites (PNCs) is to disperse high nanofiller loadings into the polymeric matrix. The high loading and uniform dispersion are limited by the unfavored polymer/nanofiller thermodynamics and the tendency for nanofiller to aggregate. In this thesis, these are circumvented by using nanoporous gold (NPG) as a scaffold for polymers to fill. The ultra-high loading (>50 vol%) is achieved by infiltrating polymer melts into NPG to produce a polymer infiltrated nanoporous gold (PING) composite. This novel composite provides promises for the next generation advanced materials for coating, optical sensors, actuators, and batteries. This thesis contributes to the better understanding of polymer kinetics under moderate confinement by varying the interfacial energy between polymer and pore wall and investigating the temperature dependence of infiltration. Confinement enhances polymer kinetics while decreasing the infiltration time dependence on Mw due to the combined effect of loss in entanglement and adsorbed chain fraction. When polymer and the wall interfacial energy is stronger, a physiosorbed layer forms, resulting in slower kinetics compared to that for weaker interfacial energy. The temperature dependence of the polymer kinetics inside NPG follows the bulk WLF behavior at lower confinement degrees, while the kinetics deviate from the bulk WLF at higher confinement levels due to the decrease in thermal expansion coefficient. Those fundamental studies on polymer kinetics enable the optimization of preparing PING composites for the use of industrial scale applications and encourage additional studies such as ion conductivities of PING. The optical properties study established UV-Vis spectroscopy as a new approach to track polymer kinetics while simultaneously broadening the potential PING applications to optically responsive membranes. This thesis presents a pathway of fabricating PING composite while kinetics studies as well as the optical study enable scientists to better understand polymers behavior under confinement and advance the toolbox for creating interconnected polymer/filler systems at high filler concentrations. 

Because 3D batteries comprise solid polymer electrolytes (SPE) confined to high surface area porous scaffolds, the interplay between polymer confinement and interfacial interactions on total ionic conductivity must be understood. This paper investigates contributions to the structure-conductivity relationship in poly(ethylene oxide) (PEO)–lithium bis(trifluorosulfonylimide) (LiTFSI) complexes confined to microporous nickel scaffolds. For bulk and confined conditions, PEO crystallinity decreases as the salt concentration (Li+:EO (r) = 0.0.125, 0.0167, 0.025, 0.05) increases. For pure PEO and all r values except 0.05, PEO crystallinity under confinement is lower than in the bulk, whereas glass transition temperature remains statistically invariant. At 298 K (semicrystalline), total ionic conductivity under confinement is higher than in the bulk at r = 0.0167, but remains invariant at r = 0.05; however, at 350 K (amorphous), total ionic conductivity is higher than in the bulk for both salt concentrations. Time–of–flight secondary ion mass spectrometry indicates selective migration of ions towards the polymer–scaffold interface. In summary, for the 3D structure studied, polymer crystallinity, interfacial segregation, and tortuosity play an important role in determining total ionic conductivity and, ultimately, the emergence of 3D SPEs as energy storage materials. 

Improving the total ionic conductivity (σ) of solid polymer electrolytes (SPEs) is critical to the development of solid–state sodium (Na) batteries. In this work, we investigate the effect of two–dimensional (2D), dual–Lewis hexagonal boron nitride (h–BN) filler on polymer structure and ion transport properties of P(EO)24:Na+ and P(EO)4:Na+ mixtures of poly (ethylene oxide) (PEO)–bis (fluorosulfonylimide) (NaFSI). Below the critical percolation concentration threshold for the h–BN flakes, x–ray diffraction (XRD) and differential scanning calorimetry (DSC) studies show that an increase in h–BN concentration initially induces an increase in PEO crystallinity followed by a decrease due to competing effects between heterogeneous nucleation of PEO lamellae and its spherulitic confinement, respectively. Raman spectroscopy reveals that h–BN improves NaFSI dissociation in the semi–dilute SPEs which is supported by density functional theory (DFT) calculations. Our calculations suggest that PEO can almost fully dissociate an NaFSI molecule with a coordination number of 6. We propose an h–BN–‘assisted’ mechanism to explain this observation, wherein h–BN aids PEO in better matching the dissociation energy of the NaFSI salt by virtue of its dual–Lewis surface chemistry. A corresponding 4x increase in σ is observed for the P(EO)24:Na+ SPEs using electrochemical impedance spectroscopy (EIS). The P(EO)4:Na+ SPEs do not show this increase likely due to a significantly different local solvation environment wherein contact ion pairs (CIPs) and aggregates (AGGs) dominate. Our findings highlight the role of filler chemistry in the design and development of composite solid polymer electrolytes for Na batteries.