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Novel nanostructured composite materialsbased on bacterial cellulose membranes (BC) and acrylate polymerswere prepared by in situ atom transfer radical polymerization (ATRP).BC membranes were functionalized with initiating sites, by reactionwith 2-bromoisobutyryl bromide (BiBBr), followedby atom transfer radical polymerization of methyl methacrylate (MMA)and n-butyl acrylate (BA), catalyzed by copper(I)bromide and N,N,N′,N″,N″-pentamethyldiethylenetriamine(PMDETA), using two distinct initiator amounts and monomer feeds.The living characteristic of the system was proven by the growth ofPBA block from the BC-g-PMMA membrane. The BC nanofibersleeving was clearly demonstrated by SEM imaging, and its extent canbe tuned by controlling the amount of initiating sites and the monomerfeed. The ensuing nanocomposites showed high hydrophobicity (contactangles with water up to 134°), good thermal stability (initialdegradation temperature in the range 241–275 °C), andwere more flexible that the unmodified BC membranes. [ABSTRACT FROM AUTHOR]

Polyamide-based nanocomposites containing surface-modified SiO2 nanofillers with different morphologies were prepared by in situ polymerisation. The nanocomposites microstructure was investigated by scanning electron microscopy, which showed a high degree of dispersion of the fillers. The isothermal crystallization kinetics, recorded with a differential scanning calorimeter, has shown a strong influence of the nanofillers morphology on the poly(tetramethyleneterephthalamide) crystallization behaviour. The strong nucleating effect of the inorganic substrate is interpreted as the combined result of a lower activation energy for the primary nucleation and a higher activation energy for the transport of chain stems to the growing lamellae. [Copyright &y& Elsevier]

Abstract: SiO2/cellulose nanocomposites were prepared using two distinct methodologies: deposition of morphological well-defined SiO2 nanoparticles at the fibres surfaces via polyelectrolytes assembly (layer-by-layer approach, LbL) and the synthesis of SiO2 nanoparticles via tetraethoxysilane (TEOS) hydrolysis in the presence of cellulose fibres. Although both methods were able to produce SiO2/cellulose composites, their final morphological properties strongly depend on the synthetic strategy employed. Whereas in the LbL approach cellulosic fibres covered with discrete spherical SiO2 nanoparticles have been obtained, for the in situ synthesis of SiO2, nanocomposites consisting predominantly on fibres homogeneously coated with a SiO2 film have been obtained. Both methodologies induced a significant decrease in the water uptake capacity of cellulose fibres. [Copyright &y& Elsevier]