Confinement Topographical Surfaces

As the fundamental understandings of TFCD formation on confined templates with trivial geometries begin to estabilish, more questions are stimulated, such as 

This work beautifully demonstrated controllability of a variety of confined LC structures using elastic property of PDMS templates, which enabled facile shape transition from spheroid to ellipsoid. The specific optical characteristic and its tunability due to a structural change of LC are highly desirable in development of switchable optical devices such as sensors. 

---

In contrast to TEM, with typical sample thicknesses in the range of lOnm-lpm, sample depths for SEM often extend into the 10-50 mm range. As such, this technique is most often used to provide a topographic image of the sample surface. However, the electron beam is not confined to the top of the surface, but also interacts with lower depths of the sample. Consequently, SEM provides information regarding the species present at varying depths of the sample (Eigure 7.28) ... 

In addition to chain molecules confined between two smooth surfaces, frictional forces were studied for grafted chains surrounded by solvent molecules [21] and for chain molecules sheared by topographically nonuniform solid surfaces [33], Tip-based simulations were also carried out to study frictional properties of confined thin films [88-92]. These topics are not covered in this review. 

Practical consequences of Eg modification in polymer films include significant changes of dissolution, diffusional and etching characteristics, mechanical creep behavior, and adhesion. Figure 17.30 shows a plot of the effective diffusion coefficient of perfluorooctane sulfonate photoacid as a function of film thickness of partially protected poly(4-t-butyloxycarbonyloxstyrene). The profile shows asymptotic behavior at 600 A, below which diffusion slows down remarkably, probably due to interfacial and confinement effects. Clearly, the interaction of the first few hundred angstroms of the film with the substrate determines its adhesion and can alter its electrical and optical properties as well as its topographical and surface characteristics. ... 

To image samples with complicated surface features, feedback modes which use iterative approach and retraction of the pipette have been developed " and a schematic is shown in Figure 2.4c. Generally, the pipette is approached to and retracted from a surface multiple times in a confined sample area rather than scanned. Data from approach curves taken at each imaging point are correlated to produce topographic... 

Figure 11.19 Temperature-gradient driven capillary instability in confined geometries. Topographic line-grid templates that were brought in contact with a liquid polymer film give risetoaquasi ID confinement ofwidth wof the free polymer surface, (a) u/= 12 pm (b) w = 6 im coexistence of free columns with circular cross-sections and wall-adsorbed columns with drop-shaped cross-sections ...

Yang G, Tang P, Yang Y, Cabral JT. Self-Assembly of AB Diblock Copolymers under Confinement into Topographically Patterned Surfaces. J Phys Chem B 2009 113 14052. 

---