Block Copolymer Systems with Ionic Interaction

4 BLOCK COPOLYMER SYSTEMS WITH IONIC INTERACTION 

Water-soluble interpolyelectrolyte complexes (IPECs) can be prepared by complexation of amphiphihc block copolymers, which comprise a hydrophobic block and an ionic or hydrophilic nonionic block [81,82]. Double hydrophilic block copolymers having an ionic block and a nonionic one can be prepared for IPECs even in 1 1 charge-to-charge ratio of the polymeric components in aqueous solution [81]. IPECs normally have a core/corona structure and are often referred to as polyion complex micelles, complex coacervate micelles, or block ionomer complexes [83,84]. 

Similar to core-shell structures reported in hydrogen-bonded block copolymer/homopolymer systems, core-shell micelle formation through electrostatic interaction were also reported. These complexes were generally formed at equimolar ratio of polycations and polyanions. But non-stoichiometric mixtures can also be employed to increase the stability 

SELF-ASSEMBLY AND MORPHOLOGY IN BLOCK COPOLYMER SYSTEMS WITH SPECIFIC INTERACTIONS 

As introduced previously, onion-like or core-shell-corona micelles were also reported in complexes formed via 

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This orientation to control the enzymatic activity was also demonstrated by the design of smart (i.e., stimuh responsive) enzyme-block copolymer systems that can be modulated by several triggers. For instance, an on-off switch of the lysozyme activity was synchronized with the reversible formation of polyion complex (PIC) micelles that are formed through electrostatic interaction between a pair of oppositely charged block copolymers with PEG segments. It was shown that an increase in the ionic strength (NaCl concentration) of the media leads to the complete disrnption of the micellar strnctnre (due to the loss of the electrostatic interactions). Lytic activity for Micrococcus luteus cells is completely inhibited when the enzyme is... 

Passive encapsulation of drugs within the nanoparticle structure produces particles that are similar to liposomal formulations, where a drug experiences favourable electrostatic, hydrophobicity-driven or ionic interactions with the polymer system (which is usually a block copolymer). This results in the drug residing in hydrophobic compartments of the polymer. There are several issues with such systems. Firstly, free drug may remain in the formulation system, and this fraction must be purified... 

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