Faculté des sciences

Liquid crystalline period variations in self-assembled block copolypeptides-surfactant ionic complexes

Li, Chaoxu ; Li, Jingguo ; Zhang, Xiuqiang ; Zhang, Afang ; Mezzenga, Raffaele

In: Macromolecular Rapid Communications, 2010, vol. 31, no. 3, p. 265-269

We investigate the complexation of ampholytic poly(N-isopropylacylamide)-block-poly- (L-glutamic acid)-block-poly(L-lysine) (PNiPAM-b-PLG-b-PLLys) triblock copolymers and PNiPAM-block-(PLG-co-PLLys) diblock copolymers with counter charged anionic and cationic surfactants. Both triblock and diblock copolymers are able to selectively form complexes... Plus

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    Summary
    We investigate the complexation of ampholytic poly(N-isopropylacylamide)-block-poly- (L-glutamic acid)-block-poly(L-lysine) (PNiPAM-b-PLG-b-PLLys) triblock copolymers and PNiPAM-block-(PLG-co-PLLys) diblock copolymers with counter charged anionic and cationic surfactants. Both triblock and diblock copolymers are able to selectively form complexes through either L-glutamic acid-cationic surfactant or L-lysine-anionic surfactant ionic pairs, depending on the protonated or deprotonated states of the ampholytic peptide units. The complexes show ordering at multiple length scales: i) the block copolymer length scale (10¹ nm), ii) the liquid crystalline length scale (10⁰ nm), and, iii) the peptidic secondary structures length scale (10⁰ nm). We show that the liquid crystalline period can be tuned by varying the random/block copolypeptide architectures and the composition of the ampholytic amino acid species.