In this paper, we discuss the use of broadband microwaves (MW) (up to 20 GHz) to characterize org... more In this paper, we discuss the use of broadband microwaves (MW) (up to 20 GHz) to characterize organic and hybrid silicon-organic thin films meant for insulation applications in micro- and nanoelectronic devices. Specifically, we will take advantage of MW propagation characteristics, to extract and examine the relationships between electrical and mechanical properties, and the chemistry of prototypical materials. The impact of moisture on the electrical behavior of any material defects will be evaluated from the impact of thermal anneal at modest temperatures on the samples. These studies will shed light on the chemical changes that occur within the dielectric films that could impact the performance and reliability, as well as provide basis for rational selection of organic dielectrics for integrated devices.
Due to the large volume fraction of nanoscale-reinforcement in cellulose-rich CNC-polymer nanocom... more Due to the large volume fraction of nanoscale-reinforcement in cellulose-rich CNC-polymer nanocomposites and the extensive surface area, nearly all the soft/polymeric phase is interfacial (interphase polymer) and therefore, under nanoconfinement. It is well-established that the dynamic properties of any interphase polymer are determined by the structure of the polymer and strength of the interactions with the hard phase, and can deviate significantly from that of the neat polymer. With optimal interfacial interactions, this leads to significantly enhanced performance in many natural composites, such as those found in crustacean and insects shells, and bone. Yet, the role of interfacial interactions, polymer structure, and nano-confinement in helicoidal cellulose nano crystal nanocomposites remains incompletely understood. Here, we use fluorescently labelled helicoidal cellulose nanocomposites and fluorescent lifetime imaging microscopy (FLIM) to study the nature of the effect of polymer structure (cross linked, blend) on the confinement effect in alkyl ammonium modified sulfate-CNC. nanocomposites. Figure 1
Polymer nanocomposites containing self-assembled cellulose nanocrystals (CNCs) are ideal for adva... more Polymer nanocomposites containing self-assembled cellulose nanocrystals (CNCs) are ideal for advanced applications requiring both strength and toughness as the helicoidal structure of the CNCs deflects crack propagation and the polymer matrix dissipates impact energy. However, any adsorbed water layer surrounding the CNCs may compromise the interfacial adhesion between the polymer matrix and the CNCs, thus impacting stress transfer at that interface. Therefore, it is critical to study the role of water at the interface in connecting the polymer dynamics and the resulting mechanical performance of the nanocomposite. Here, we explore the effect of polymer confinement and water content on polymer dynamics in CNC nanocomposites by covalently attaching a fluorogenic water-sensitive dye to poly(diethylene glycol methyl ether methacrylate) (PMEO2MA), to provide insights into the observed mechanical performance. Utilizing fluorescence lifetime imaging microscopy (FLIM), the lifetime of dye fluorescence decay was measured to probe the polymer chain dynamics of PMEO2MA in CNC nanocomposite films. The PMEO2MA chains experienced distinct regions of differing dynamics within Bouligand structures. A correlation was observed between the average fluorescence lifetime and the mechanical performance of CNC films, indicating that polymer chains with high mobility improved the strain and toughness. These studies demonstrated FLIM as a method to investigate polymer dynamics at the nanosecond timescale that can readily be applied to other composite systems.
In this paper, we discuss the use of broadband microwaves (MW) (up to 20 GHz) to characterize org... more In this paper, we discuss the use of broadband microwaves (MW) (up to 20 GHz) to characterize organic and hybrid silicon-organic thin films meant for insulation applications in micro- and nanoelectronic devices. Specifically, we will take advantage of MW propagation characteristics, to extract and examine the relationships between electrical and mechanical properties, and the chemistry of prototypical materials. The impact of moisture on the electrical behavior of any material defects will be evaluated from the impact of thermal anneal at modest temperatures on the samples. These studies will shed light on the chemical changes that occur within the dielectric films that could impact the performance and reliability, as well as provide basis for rational selection of organic dielectrics for integrated devices.
Due to the large volume fraction of nanoscale-reinforcement in cellulose-rich CNC-polymer nanocom... more Due to the large volume fraction of nanoscale-reinforcement in cellulose-rich CNC-polymer nanocomposites and the extensive surface area, nearly all the soft/polymeric phase is interfacial (interphase polymer) and therefore, under nanoconfinement. It is well-established that the dynamic properties of any interphase polymer are determined by the structure of the polymer and strength of the interactions with the hard phase, and can deviate significantly from that of the neat polymer. With optimal interfacial interactions, this leads to significantly enhanced performance in many natural composites, such as those found in crustacean and insects shells, and bone. Yet, the role of interfacial interactions, polymer structure, and nano-confinement in helicoidal cellulose nano crystal nanocomposites remains incompletely understood. Here, we use fluorescently labelled helicoidal cellulose nanocomposites and fluorescent lifetime imaging microscopy (FLIM) to study the nature of the effect of polymer structure (cross linked, blend) on the confinement effect in alkyl ammonium modified sulfate-CNC. nanocomposites. Figure 1
Polymer nanocomposites containing self-assembled cellulose nanocrystals (CNCs) are ideal for adva... more Polymer nanocomposites containing self-assembled cellulose nanocrystals (CNCs) are ideal for advanced applications requiring both strength and toughness as the helicoidal structure of the CNCs deflects crack propagation and the polymer matrix dissipates impact energy. However, any adsorbed water layer surrounding the CNCs may compromise the interfacial adhesion between the polymer matrix and the CNCs, thus impacting stress transfer at that interface. Therefore, it is critical to study the role of water at the interface in connecting the polymer dynamics and the resulting mechanical performance of the nanocomposite. Here, we explore the effect of polymer confinement and water content on polymer dynamics in CNC nanocomposites by covalently attaching a fluorogenic water-sensitive dye to poly(diethylene glycol methyl ether methacrylate) (PMEO2MA), to provide insights into the observed mechanical performance. Utilizing fluorescence lifetime imaging microscopy (FLIM), the lifetime of dye fluorescence decay was measured to probe the polymer chain dynamics of PMEO2MA in CNC nanocomposite films. The PMEO2MA chains experienced distinct regions of differing dynamics within Bouligand structures. A correlation was observed between the average fluorescence lifetime and the mechanical performance of CNC films, indicating that polymer chains with high mobility improved the strain and toughness. These studies demonstrated FLIM as a method to investigate polymer dynamics at the nanosecond timescale that can readily be applied to other composite systems.
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