Chain block designs

Fig. 10 Block copolymer with amino group with distinctive values in the side chain, a Design of a new block copolymer with two amino groups with higher and lower pjfa values in each of the monomer units, b Schematic representation of the side chain substitution of PEG-PBLA through aminolysis reaction, resulting in the formation of various kinds of PEG-polyaspartamide with different amino groups in the side chain...

The generic features of these approaches are known from experience in anionic polymerization. However, radical polymerization brings some issues and some advantages. Combinations of strategies (a-d) are also known. Following star formation and with appropriate experimental design to ensure dormant chain end functionality is retained, the arms may be chain extended to give star block copolymers (321). In other cases the dormant functionality can be retained in the core in a manner that allows synthesis of mikto-arm stars (324). 

Optimal pre-organization of the y-peptide backbone towards the formation of open-chain turn-like motifs is promoted by unlike-y " -amino acid residues. This design principle can be rationalized by examination of the two conformers free of syn-pentane interaction (f and II", Fig. 2.34). Tetrapeptide 150 built from homo-chiral unlike-y -amino acid building blocks 128e has been shown by NMR experiments in pyridine to adopt a reverse turn-like structure stabilized by a 14-mem-bered H-bond pseudocycle [202] (Fig. 2.37 A). 

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