Synthesis and Testing of Nonhalogenated Alkyne-Containing Flame-Retarding Polymer Additives

Abstract

In this paper, the synthesis and thermal properties of several alkyne-containing materials are discussed. The materials were synthesized using palladium/copper-or palladium/zinc-mediated crosscoupling reactions between multibrominated aromatics and phenylacetylene. Therefore, in one step, commercially available brominated flame retardants can be converted into nonhalogenated high-char materials using transition metal catalysis. The materials synthesized included polymers, oligomers, carbonates, and diphenyl ethers. The thermal properties of the synthesized materials were studied using differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). In general, the DSC and TGA data showed that the synthesized materials were all high-char-yielding materials. Further, DSC data showed that the materials which had o-dialkyne substitutions (enediyne systems) generally cross-linked at lower temperatures than materials that had m-dialkynes. However, TGA showed that the materials with ortho substitutions, especially those with multiple ortho substitutions, generally had higher char yields than those with meta substitutions. The materials were blended into polycarbonate and tested for ignition resistance using the UL-94 flame test. Alkyne-containing oligomer 9, used in conjunction with 0.5 wt % of a bromide-containing flame retardant, provided flame retardancy in polycarbonate according to the UL-94 test. This indicates that alkyne-containing materials, acting as condensed phase flame retardants, can substantially lower the amount of halogen content needed for flame retardancy in polycarbonate.

Flame Retardants: Overview

“…With the phase out and deselection of certain classes of flame-retardant chemicals, there is increased study looking at other chemistries that may impart flame retardancy, such as transition metals (char catalysis) (92,93), and all-carbon-based flame retardants that impart char formation through cross-liking during fire conditions (94)(95)(96)(97)(98)(99)(100)(101)(102)(103)(104)(105). Other niche chemistries may be exploited further as new chemistries are found and studied, especially as existing flame retardants are found to have unfavorable environmental profiles.…”

Triazole-forming waterborne polyurethane composites fabricated with silane coupling agent functionalized nano-silica

“…This could be attributed to the fact that alkyne groups as a cross-linker can form reticulated alkenes and participate in cyclo-trimerization reaction. The char layer covering the material as protective barrier prevented the formation of volatile compounds and the heat transfer into inner part of the material [21,30], which can make the material flame retarding.…”

Study on thermal decomposition kinetics of N,N′-bis(5,5-dimethyl-2-phospha-2-thio-1,3-dioxan-2-yl)ethylenediamine in air

“…In particular, bromodiphenyl ether fire retardants can not only release toxic hydrogen bromide but also carcinogenic bromofuran during the thermal decomposition, which made the European Union, the United States and other countries or areas begin to restrict their applications [2,3]. Thus, the research on fire retardants that are nearly non-toxic or those that do not release corrosive gases during decomposition greatly pushes the development of fire retardants containing non-halogen materials [4][5][6][7][8]. There are wide varieties of fire retardants containing phosphorus [9][10][11].…”