کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5183926 1381033 2010 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Polypyrrole nanocoatings of poly(styrene-co-methacrylic acid) particles
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آلی
پیش نمایش صفحه اول مقاله
Polypyrrole nanocoatings of poly(styrene-co-methacrylic acid) particles
چکیده انگلیسی

In this study the properties of polypyrrole (PPy) nanocoating over poly(styrene-co-methacrylic acid) (PS-MAA) particles were investigated. Monodisperse PS-MAA templates were obtained by free surfactant emulsion polymerization. The addition of methacrylic acid into the monomer feed mixture reduced particle size, ionic charge and hydrophobicity of the template surface. Correlations between template sizes and compositions, PPy confinement (granularity, shell size, etc.) and electrical conductivity, σ, are discussed. After dissolving the PPy/PS-MAA composites in tetrahydrofurane, PPy void spheres are obtained proving the core-shell nature of the coated particles. Bare styrene templates show densely packed PPy coatings and electrical conductivities near 7 S cm−1 at high PPy loadings; on the contrary, at the same PPy mass percentage, the richer methacrylic acid particles show low packed PPy grains and conductivities that fall to 0.8 S cm−1. In core-shell particles the PPy mass per unit area, Γ, is the key parameter which determines the insulator-conductor transition for any particle size. The conductivity values of PPy/PS-MAA composites follow a percolation law: σ∝(Γ−Γc)t, with a critical threshold Γc=(0.262 ± 0.002)×10−6 g cm−2. The critical exponent obtained t = 1.98 ± 0.07 agrees with the predicted value t = 2.0 for three-dimensional lattices of random resistors.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Polymer - Volume 51, Issue 8, 6 April 2010, Pages 1728-1736
نویسندگان
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