The Use Of Micro-phase Separation To Form Self-consistent Field Theory Of Multi-component Polymer Blends And Polymer Blend Brush System

Both the system of mixed polymer brush and high impact polypropylene (HIPP) were studied by the self-consistent field theory (SCFT). The blending system including homopolymer A, homopolymer B, diblock copolymer A-b-B as well as the alternating polymer (A-b-B)4 was studied by SCFT, in order to simulate the morphology of high-impact polypropylene. The influences of the volume fraction and chain length of each component on the morphology were systematically investigated. The blending system can undergo phase separation to form a multi core-shell structure, in which PE is dispersed in EPR and EPR is further disperses in the matrix of PP, with PP-b-PE staying at the interface of EPR and PP.Most studies are focused on mixed polymer brushes grafted onto a flat substrate, ignoring the effect of the substrate curvature. The effect, however, plays an important role in microphase separation of mixed polymer brushes when the curvature radius is comparable to the polymer size. The difficulty lies in the numerical discontinuity and instability at the grafting region. Thanks to the "masking" technique that employs a cavity function to depict a hard wall with a certain thickness, the phase separation of mixed polymer brushes was investigated at a nanosphere with its radius comparable to the polymer size. A series of structures with island number ranging from 2 to 12 (except for 11) were obtained. These islands arrange themselves in a highly symmetric way on the spherical surface, very similar to packing pattern with the same number of microspheres. This part was focused on the effects of many parameters on the island structures, such as grafting density ratio, the total grafting density, chain length disparity and the substrate curvature. The results shows that the island number will increase as the grafting density ration increases. When the grafting density ration is very high, however, a special layered structure was observed. The total grafting density has little influence on the formation of island structures. Increasing the chain length disparity will induce the structure transition from a layered structure to island structures and finally to an inverse layered structure. The substrate curvature plays a key role in determining the type of island structures. The island number and the brush height will decrease as the substrate curvature increases.