Miscibility in Organic/Inorganic Hybrid Nanocomposites Suitable for Microelectronic Applications: Comparison of Modulated Differential Scanning Calorimetry and Fluorescence Spectroscopy

Free Volume Effect via Various Chemical Structured Monomers on Adhesion Property and Relative Permittivity in Acrylic Pressure Sensitive Adhesives

Acrylic pressure-sensitive adhesives (PSAs) are used as fixatives between layers of a display. PSAs’ function is an important factor that determines the performance of the display. Of the various display types available, the touch screen panel (TSP) of smart devices is firmly related to the relative permittivity of the elementals. Therefore, adjusting the relative permittivity of the PSA is indispensable for driving the TSP. Accordingly, selected acrylic pre-polymers were polymerized and the pre-polymer was blended and cross-linked with monomers with different chemical structure to adjust the relative permittivity. The monomers were hexametyldisiloxane (HMDS), N-vinylcaprolactam (NVC), tert-butyl acrylate (TBA), and isooctadecyl acrylate (ISTA). The gel fraction and transmittance as a function of the monomers show a similar result to the pure acrylic PSA. However, the gel fraction value decreased to about 90% and the transmittance decreased to about 85%, due to the immiscibility between nonpolar HMDS and acrylic PSA. On the other hand, the adhesion properties were improved when NVC was added because of the polarity of the nitrogen group. In addition, the relative permittivity of the PSA decreased regardless of the monomer chosen. There was, however, a difference in the optimal content of each monomer, and NVC decreased from 4 phr content to about 3.4 in reducing relative permittivity. Through the above results, it was confirmed that NVC having a nitrogen group is most advantageous in lowering adhesion properties and relative permittivity, and necessitates further research based on the findings.

Dendrimeric organosiloxane with thermopolymerizable –OCFCF2 groups as the arms: synthesis and transformation to the polymer with both ultra-low k and low water uptake

A novel fluoro-containing dendrimeric macromolecule with cyclic siloxane as the core and aryl-trifluorovinyl-ether (–OCFCF₂) units as the arms was reported.

Development of a polybenzoxazine/TSBA-15 composite from the renewable resource cardanol for low-k applications

Scheme shows the synthesis of a cardanol-based polybenzoxazine composite for low-dielectric constant applications.

Non-porous low-k dielectric films based on a new structural amorphous fluoropolymer

A non-porous and amorphous fluoropolymer PFN with low dielectric constant of 2.33 and dielectric loss less than 1.2 × 10(-3) is reported here. PFN also exhibits good mechanical properties and high thermostability. This study is a new example of a fully dense material showing a low k value and having good thermo/mechanical properties.

Nano-organized shells and their application in controlled release

Aim: The release characteristics of hollow-shell drug-delivery carriers are strongly dependent on the properties of the capsule shell, in particular its thickness and porous structure. The aim of this investigation was to conduct a detailed study of the relationship between capsule processing parameters, the resulting shell characteristics and subsequent release of an encapsulated liquid. Methods: Hollow spherical polymer capsules of constant outer diameter were prepared using electrohydrodynamic processing and the shell thickness of the capsules varied between 100–150 nm. For each type of capsule, the size and structure of channels present in the shell were extensively studied using electron microscopy. To investigate the effect upon the release characteristics the capsules were loaded with a water-soluble dye of molecular weight approximately 961 and release profiles determined using ultraviolet spectroscopy. Results: The channel diameter was found to be similar for all shell thicknesses (˜5 nm). The majority of the channels were radially aligned and through the full thickness of the shell. It was found that the rate of release decreased with increasing shell thickness and it became increasingly linear with respect to time; modeling confirmed that the release was diffusion dominated. Conclusions: The results of the study show that by controlling the structural characteristics of the shell of the hollow drug-carrier particles at the nanoscale through their forming methodology, the release profile can in turn be tailored according to the application requirements.

Stimulus-responsive liquids for encapsulation storage and controlled release of drugs from nano-shell capsules

Drug-delivery systems with a unique capability to respond to a given stimulus can improve therapeutic efficacy. However, development of such systems is currently heavily reliant on responsive polymeric materials and pursuing this singular strategy limits the potential for clinical translation. In this report, with a model system used for drug-release studies, we demonstrate a new strategy: how a temperature-responsive non-toxic, volatile liquid can be encapsulated and stored under ambient conditions and subsequently programmed for controlled drug release without relying on a smart polymer. When the stimulus temperature is reached, controlled encapsulation of different amounts of dye in the capsules is achieved and facilitates subsequent sustained release. With different ratios of the liquid (perfluorohexane): dye in the capsules, enhanced controlled release with real-time response is provided. Hence, our findings offer great potential for drug-delivery applications and provide new generic insights into the development of stimuli drug-release systems.

Hierarchical assembly of nanostructured organosilicate networks via stereocomplexation of block copolymers

The effect of the stereochemistry of polylactide (PLA)-based block copolymers on templated inorganic nanostructures has been investigated from the self-assembly of a stereoisomer pair/organosilicate mixture followed by organosilicate vitrification and copolymer thermolysis. Isomeric PLA homopolymers, block copolymers, and a stereoblock copolymer were prepared by ring-opening polymerization of D-, L-, or rac-lactide using an organocatalytic catalyst. Both differential scanning calorimetry and atomic force microscopy showed the formation of a stereocomplex between enantiomeric stereoisomers, that is, block copolymer/block copolymer and block copolymer/homopolymer mixtures as well as a stereoblock copolymer. The unique noncovalent interactions driven by stereocomplexation of D- and L-lactide provided supramolecular structures with a hierarchical order as characterized by distinctive vertical and horizontal growth of toroidal nanostructured inorganic features. This study demonstrates the potential of hierarchically assembling suprastructures that bridge the nano- to mesoscale feature sizes in the design of tunable functional nanomaterials suitable for future applications of microelectronics, material science, and bioengineering.

Pore morphologies in disordered nanoporous thin films

Materials with nanometer size heterogeneities are commonplace in the chemical and biological sciences (e.g, polymer blends, microemulsions, gels) and often exhibit complex morphologies. Although this morphology has a dramatic effect on the materials' properties, it is often difficult to accurately characterize. We describe a method, using small-angle X-ray scattering data, of generating representative three-dimensional morphologies of isotropic two-phase materials where the morphology is disordered, and we apply this to thin films containing nanometer sized pores with a range of porosities (4-44%). These representations provide a visualization of the pore morphology, give the pore size scale and extent of interconnection, and permit the determination of the transitions from closed pore to interconnected pores to bicontinuous morphology.