Evaporation technique, slow-solvent

To remove any metallic Au, the reaction mixture is evaporated to dryness and subsequently passed over a commercial terra infusorii column in a minimal volume of solvent. Crystallization may be performed by slow diffusion of a two-layer system. Yields are low (10-60%). The metal evaporation technique (see 8.2.1.2) gives higher yields than the sodium borohydride method. 

The slow solvent evaporation technique afforded milky nanosphere dispersions. No effect of the polymer/protein/lipid weight ratios on the dispersion stability was detected, at least in the investigated range. 

By taking into account the difficulties connected to the slow solvent evaporation technique, a new procedure for nanoparticle preparation by co-precipitation was set up. This technique does not use chlorinated solvents and energetic mixing, which are both known to cause appreciable protein denaturation[17,18]. 

Samples for the viscoelastic experiments were prepared by a conventional slow-solvent-evaporation technique (1) followed by vacuum drying. For ease in handling in certain experiments, some samples were lightly cured using a 30-MRad dose of electrons other experiments were carried out on uncured materials. Transmission electron microscopy (Phillips Model 200) was used to investigate possible morphological features in the block polymers and blends. Details of the various staining techniques used are presented elsewhere (1,11,12,13). 

PLLA is a crystallizable polymer with melting temperature at around 175°C. Semicrystalline PLLA films can be prepared by various techniques, such as solution casting with a slow evaporation rate of solvent, isothermal crystallization from the melt, and annealing of amorphous samples. Since PLLA has a glass transition temperature (Tg) of 60 "C, which is higher than room temperature, a completely amorphous film can be obtained by melt quenching. 

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