Block coplymers

The SBjj diblock in which the styrene block is made first in cyclohexane, followed by the dipiperidise ethane modifier to the styreyl lithium then the butadiene to form this block coplymer. The reader may see the difference as illustrated in the following tables (XIII - XIV) as the physical properties vary from B S to SB ... 

Breiner T (2001) Block coplymers with functionalized poly(2-hydroxyethyl methacrylate) segments for optical data storage. PhD Thesis, University of Bayreuth... 

Block coplymers exhibit surface activity since one of the blocks is soluble in one of the phases and the other is miscible in the other phase, e.g., AB block, A hydrophilic, B hydrophobic... 

Scheme 29 illustrates the synthetic routes to three classes of silicone-urethane block copolymers that were reported by Benrashid et al. It is interesting that the solvents from which the siloxane-urethane block coplymers were cast have a significant influence on microphase segregation. For example, films cast from THF had a higher siloxane concentration at the surface relative to polymers cast from DMAc/ CH2CI2 or dioxane. 

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