Rice-grained morphology

Fig. 17.4 Transmission electron micrograph of polyaniline particles synthesized in aqueous media using a reactive poly(2-vinyl pyridine-co-4-aminostyrene) steric stabilizer. Note the polydisperse rice grain morphology. (Reproduced with permission from Ref. 46.)...

Armes and coworkers have investigated the structure of both PAn colloid particles [stabilized with poly(vinyl alcohol)] and electrochemically prepared PAn films. In both cases the fundamental morphology was nanoparticles of up to 20 nm in diameter. Colloid particles were rice grain shaped. Thick films showed submicronsized features that appear to be aggregates of the smaller particles. 

Figure 15. Variations in aragonite crystal shapes in selected laminae Croni an offshore core in Waldsea Lake. Saskatchewan. Examples shown on the left illustrate laminae composed mainly of ellipsoidal (rice-grained) crystals examples on the right show laminae in which the aragonite is mainly of acicular morphology (modified from Greengrass el al., 1999 Deliqiat et al., 1999).

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