COMPUTATIONAL CHALLENGES IN CONDENSED MATTER APPLICATIONS
Our paper focuses on computer simulation of the transport processes in nanoporous systems. This systems are considerably more complex than diffusion in homogeneous phases or in macroporous systems. The pathways in nanoporous systems are, by design, similar to the dimensions of the diffusing species. Adsorbate-adsorbate and adsorbate-adsorbent interactions are enhanced. The energetic of transport differs from molecular theory often to reflect activated processes with apparent activation energies. Entropic factors also play an increasing role in the transport. Dissolution as well as diffusion between chains must be considered in polymers. Adsorbent flexibility is a factor of varying significance in both inorganic and organic solids. Simple extensions of homogeneous theories are inadequate, as these specific interactions need to be included. This paper deals with an empirical algorithm, which analyses the physical parameters over the copolymer network properties as a relation between the molecular ratios of copolymer sequences. We also present the performance of the proposed method in relation to the fitness function and the local twist.
Amphyphylic copolymers as water delivery systems
Abstract Various polydimethylsiloxane-co-poly(methacrylic acid) networks were prepared by initiating the radical polymerization of methacrylic acid in presence of azoester containing polydimethylsiloxane (PDMS) and of ethyleneglicole dimethacrilate as crosslinking agent. The chemical structure and the thermal behavior of these hydrophobic–hydrophilic gels were established by IR spectroscopy, scanning electron microscopy and differential scanning calorimetry. Also, the water delivery tests were performed and the possibility to use amphyphilic copolymers as systems to mention humidity in soil is discussed. According to the experimental results a mechanism of water delivery were proposed where the hydrophilic (poly(methacrylic acid)) and hydrophobic (PDMS) sequences have different rolls in this mechanism.
Interpenetrating polymer networks of poly(dimethylsiloxane) with polystyrene, polybutadiene and poly(glycerylpropoxytriacrylate)
The synthesis of full and semi interpenetrating networks (IPNs) based on poly(dimethy1-siloxane) (PDMS)/polystyrene, PDMS/polybutadiene and PDMS/poly(glycerylpropoxytriacry-late)1 is described. PDMS was used as host polymer in most cases. PDMS networks were prepared with two prepolymers having different number-average molecular weights between junctions, Mc = 15 · l03 and Mc = 75 · l03. Physical properties of IPN samples such as stress-strain behaviour, swelling and glass transition temperature (Tg) were examined. IPNs of both PDMS/polystyrene and PDMS/poly(glycerylpropoxytriacrylate) exhibit superior mechanical and elastomeric properties with respect to pure PDMS network. Most of the IPN systems studied in this work display two Tgs and indicate phase separation.