Colloidal particle defect structure

The importance of SPM for the study of monolayers is that it allows the visualization of the structure and defects of transferred and self-assembled monolayers on solid substrates at length scales from <0.1 nm to > 10 pm. It is not fyet ) possible to image monolayers at liquid/fluid Interfaces with SPM techniques. However, it has already been shown that it is feasible to measure interaction forces between a colloidal particle and such interfaces in the presence and absence of monolayers ). 

Topological defects are often needed to equilibrate an ordered system. There are two different possibilities here. First, the defects can occur to relieve intrinsic ( bulk ) frustrations (for instance, between the twist and layered structures in TGB phases). Second, the defects can occur simply because the system is bounded or because there are foreign inclusions, such as colloidal particles or droplets in a liquid crystalline host. 

Structures and Structural Defects in Colloidal Particles Altered In-situ in HREM, Z.C. Kang, J. Tong and L. Eyring, 20th Rare Earth Research Conference, Monterey, September 1993, J. Alloys Compd., 207-208, 420 23 (1994). 

The signiflcant recent advances in both colloidal and polymer chemistries have enabled the successful fabrication of complex, defect-free tianoslruclures following a bottom-up approach [353]. Two recent related examples are mentioned to stress the point. Recently, triblock copolymer with divalent counter-ions in mixed solvents led to the formation of particles with tunable internal structure mimicking lipid anphiphiles for potential use in drug delivery. The mechanism of formation involves either nanophase separation within the triblock copolymer nanoparticle upon addition of water or microemulsion formation similar to that in lipid systems... 

Structurally, asphaltene contains flat sheets of condensed aromatic systems that may be interconnected by sulfide, ether, aliphatic chains or naphthenic ring linkages. Gaps and holes appear as defect centers in the aromatic systems with heterocyclic atoms coordinated to transition metals such as vanadium and nickel, most likely caused by free radicals. Due to the complexity and the large size of asphaltene molecules, asphaltene particles conveniently faU within the colloidal range. The stmcture of asphaltene has been determined previously by the x-ray diffraction method and is shown as Figure 2. 

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