Flame-retardant materials based on phosphorus-containing polyhedral oligomeric silsesquioxane and bismaleimide/diallylbisphenol a with improved thermal resistance and dielectric properties

The Recent Advances of Polymer-POSS Nanocomposites With Low Dielectric Constant

This study provides a comprehensive overview of the preparation methods for polyhedral oligomeric silsesquioxane (POSS) monomers and polymer/POSS nanocomposites. It focuses on the latest advancements in using POSS to design polymer nanocomposites with reduced dielectric constants. The study emphasizes exploring the potential of POSS, either alone or in combination with other materials, to decrease the dielectric constant and dielectric loss of various polymers, including polyimides, bismaleimide resins, poly(aryl ether)s, polybenzoxazines, benzocyclobutene resins, polyolefins, cyanate ester resins, and epoxy resins. In addition, the research investigates the impact of incorporating POSS on improving the thermal properties, mechanical properties, surface properties, and other aspects of these polymers. The entire study is divided into two parts, discussing systematically the role of POSS in reducing dielectric constants during the preparation of POSS composites using both physical blending and chemical synthesis methods. The goal of this research is to provide valuable strategies for designing a new generation of low dielectric constant materials suitable for large-scale integrated circuits in the semiconductor materials domain.

Flame-Retardant Performance of Transparent and Tensile-Strength-Enhanced Epoxy Resins

In this study, a flame-retardant additive with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) groups denoted DSD was successfully synthesized from DOPO, 4,4′-diaminodiphenyl sulfone (DDS), and salicylaldehyde. The chemical structure of DSD was characterized by FTIR–ATR, NMR, and elemental analysis. DSD was used as an amine curing agent, and the transparent, tensile strength-enhanced epoxy resins named EP–DSD were prepared via thermal curing reactions among the diglycidyl ether of bisphenol A (DGEBA), 4,4′-diaminodiphenylmethane (DDM), and DSD. The flame-retardancy of composites was studied by the limiting oxygen index (LOI) and UL-94 test. The LOI values of EP–DSD composites increased from 30.7% for a content of 3 wt % to 35.4% for a content of 9 wt %. When the content of DSD reached 6 wt %, a V-0 rating under the UL-94 vertical test was achieved. SEM photographs of char residues after the UL-94 test indicate that an intumescent and tight char layer with a porous structure inside was formed. The TGA results revealed that EP–DSD thermosets decomposed ahead of time. The graphitization degree of the residual chars was also investigated by laser Raman spectroscopy. The measurement of tensile strength at breaking point shows that the loading of DSD increases the tensile strength of epoxy thermosets. Py-GC/MS analysis shows the presence of phosphorus fragments released during EP–DSD thermal decomposition, which could act as free radical inhibitors in the gas phase. Owing to the promotion of the formation of intumescent and compact char residues in the condensed phase and nonflammable phosphorus fragments formed from the decomposition of DOPO groups, EP–DSD composites displayed obvious flame-retardancy.