Self-segregation

Einally, linear amphiphilic PEG-Z)-PLLA-Z)-PLL triblock copolymers were synthesized and blended with PLLA for film formation. Investigation of the film surface revealed an enrichment of PLL blocks on the surface of the PLLA film. Human osteoblast tests performed on different PLLA films showed that the triblock copolymers were much more effective in promoting cell adhesion and proliferation compared to the PEG-6-PLLA diblock-modified and virgin PLLA films. The self-segregation of the PEG-6-PLLA-A-PLL triblock copolymers on the film surface demonstrated a potential application in the preparation of functional scaffolds for tissue engineering. 

We don t find it problematic that organizational members with perceived similarity congregate. Anyone who has travelled abroad knows the instant (often atypical) bond that forms when one encounters one s countryman. We only find such behavior problematic when self-segregation... 

Students from various identity groups no longer self segregate and embrace each other fully. They choose to be part of a culture that celebrates diversity. We have fostered a culture of TRUST on campus because no one can really ask the tough questions or have the difficult conversation without trust. 

Of the above, two types of complexes are considered to form in solutions of nonionic polymers. One type (Type 5) occurs in block copolymers consisting of polar and nonpolar blocks. In this case, the polymer molecule assumes a conformation in solution characterized by self-segregation of polar and nonpolar blocks. The surfactant molecules locate themselves at the interfaces between these segregated regions. A quantitative description of such a block copoloymer-surfactant complex has been developed in our earlier paper. >°... 

This self-segregation or self-micellization tends to create significant concentration fluctuations at the core-shell interface. 

Figure B3.6.5. Phase diagram of a ternary polymer blend consisting of two homopolymers, A and B, and a synnnetric AB diblock copolymer as calculated by self-consistent field theory. All species have the same chain length A and the figure displays a cut tlirough the phase prism at%N= 11 (which corresponds to weak segregation). The phase diagram contains two homopolymer-rich phases A and B, a synnnetric lamellar phase L and asynnnetric lamellar phases, which are rich in the A component or rich in the B component ig, respectively. From Janert and Schick [68].

THEORY OF SURFACE SEGREGATION SELF-CONSISTENT DETERMINATION OF THE CONCENTRATION PROFILE... 

Unlike the heterostructures whose periodic structure must be accurately controlled, the formation of nanocomposite structure is self-organized based upon thermodynamically driven spinodal phase segregation [118-121]. For the CVD... 

Tailoring block copolymers with three or more distinct type of blocks creates more exciting possibilities of exquisite self-assembly. The possible combination of block sequence, composition, and block molecular weight provides an enormous space for the creation of new morphologies. In multiblock copolymer with selective solvents, the dramatic expansion of parameter space poses both experimental and theoretical challenges. However, there has been very limited systematic research on the phase behavior of triblock copolymers and triblock copolymer-containing selective solvents. In the future an important aspect in the fabrication of nanomaterials by bottom-up approach would be to understand, control, and manipulate the self-assembly of phase-segregated system and to know how the selective solvent present affects the phase behavior and structure offered by amphiphilic block copolymers. 

Tschierske, C. (1998) Non-conventional liquid crystals - the importance of micro-segregation for self-organisation. Journal of Materials Chemistry, 8,1485-1508. 

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