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Silica particles with grafted poly­(methyl methacrylate) brushes, SiO2-g-PMMA, were prepared via activator regeneration by electron transfer (ARGET) atom transfer radical polymerization (ATRP). The grafting density and dispersity of the polymer brushes was tuned by the initial ATRP catalyst concentration ([CuII/L]0). Sparsely grafted particle brushes, which also displayed an anisotropic string-like structure in TEM images, were obtained at very low catalyst concentrations, [CuII/L]0 < 1 ppm. The effect of the initial catalyst concentration on dispersity and initiation efficiency in the particle brush system was similar to that observed in the synthesis of linear PMMA homopolymers. The kinetic study revealed a transition from controlled radical polymerization to a less controlled process at low monomer conversion, when the [CuII/L]0 decreased below about 10 ppm.

In this study, novel biobased pressure-sensitive adhesives (PSAs) derived from epoxidized soybean oils and carboxylic acid-terminated polyesters were developed with flame retardance, thermal stability, and peel strength comparable to those of current PSAs. The dynamic mechanical analysis indicated that the PSAs exhibited a dynamic mechanical response consistent with related high-performance PSAs. The thermal properties of the PSAs were investigated by thermogravimetric analysis, and the results suggested that the onset decomposition temperatures in both nitrogen and air atmospheres were improved by incorporating both 9,10-dihydro-10-[2,3-di­(hydroxycarbonyl)­propyl]-10-phosphaphenanthrene-10-oxide (DDP) and 2-(6-oxido-6H-dibenz<1,2>oxaphosphorin-6-yl)-1,4-hydroxyethoxyphenylene (DOPO-HQ-HE) as the flame-retardant monomer. Microscale combustion calorimetry, the limiting oxygen index test, UL-94, and the test method for flame resistance of PSA tapes were used to evaluate the flame retardance of the PSAs. With an increase in the content of the flame-retardant monomers, the flame retardance of two phosphorus-containing PSAs improved. The PSAs were based on renewable materials without any volatile organic compound, thus being environmentally friendly together with having the expected thermal stability and flame retardance. If we take advantage of these features, the PSAs can provide more opportunities for versatile applications.

No abstract

Semi-aromatic polyesters containing special aryl ether and/or ketone structures show good flame retardancy via binding small-molecule free radicals and forming char during combustion.