title: Determination of Concentration of Amphiphilic Polymer Molecules on the Surface of Encapsulated Semiconductor Nanocrystals.
abstract: We present a method for the determination of the average number of polymer molecules on the surface of A(II)B(VI) luminescent core-shell nanocrystals (CdSe/ZnS, ZnSe/ZnS quantum dots, and CdS/ZnS nanorods) encapsulated with amphiphilic polymer. Poly(maleic anhydride-alt-1-tetradecene) (PMAT) was quantitatively labeled with amino-derivative of fluorescein and the average amount of PMAT molecules per single nanocrystal was determined using optical absorption of the dye in the visible spectral range. The average amount of PMAT molecules grows linearly with the surface area of all studied nanocrystals. However, the surface density of the monomer units increases nonlinearly with the surface area, because of the increased competition between PMAT molecules for Zn-hexanethiol surface binding sites. The average value of zeta potential (ζ = -35 mV) was found to be independent of the size, shape, and chemical composition of nanocrystals at fixed buffer parameters (carbonate-bicarbonate buffer, pH 9.5 and 5 mM ionic strength). This finding is expected to be useful for the determination of the surface density of remaining carboxyl groups in PMAT-encapsulated nanocrystals.
authors: Institute for Physical Chemical Problems, Belarusian State University , Leningradskaya str. 14, Minsk 220030, Belarus.
authors: Aleksandra
authors: A
authors: Fedosyuk
authors: Institute for Physical Chemical Problems, Belarusian State University , Leningradskaya str. 14, Minsk 220030, Belarus.
authors: Aliaksandra
authors: A
authors: Radchanka
authors: Institute for Physical Chemical Problems, Belarusian State University , Leningradskaya str. 14, Minsk 220030, Belarus.
authors: Artsiom
authors: A
authors: Antanovich
authors: Institute for Physical Chemical Problems, Belarusian State University , Leningradskaya str. 14, Minsk 220030, Belarus.
authors: Anatol
authors: A
authors: Prudnikau
authors: Institute of Physical Organic Chemistry, National Academy of Sciences of Belarus , Minsk 220072, Belarus.
authors: Maksim V
authors: MV
authors: Kvach
authors: Institute of Physical Organic Chemistry, National Academy of Sciences of Belarus , Minsk 220072, Belarus.
authors: Vadim
authors: V
authors: Shmanai
authors: Institute for Physical Chemical Problems, Belarusian State University , Leningradskaya str. 14, Minsk 220030, Belarus.
authors: Mikhail
authors: M
authors: Artemyev