Functionalization of Block Copolypeptides via Thiol-yne Addition and Their Self-assembly Behavior in Solutions
Ping Chen;Wen-xin Fu;Jiangsu Key Laboratory for Chemistry of Low-dimensional Materials,School of Chemistry and Chemical Engineering,Huaiyin Normal University;Institute of Chemistry,Chinese Academy of Sciences;
A series of polypeptide-based amphiphilic hybrid copolymers were synthesized via the combination of ring-opening polymerization( ROP) and thiol-yne click reaction. First,poly( ethylene glycol)-block-poly( γ-propargyl-L-glutamate)( PEG-b-PPLG) diblock copolymers were prepared by ROP using a monoamine terminated poly( ethylene glycol)( PEG-NH2) as the initiator. Subsequently,the PPLG block was modified with a saturated hydrocarbon( 1-octanethiol) or a superhydrophobic fluorinated side group( 1-mercapto-1H,1H,2H,2H-perfluorooctane) by thiol-yne reaction with high efficiency. The self-assembly behavior of all obtained copolymers in solutions was finely investigated and characterized using Fourier transform infrared( FTIR) spectroscopy,circular dichroism( CD) spectroscopy,dynamic light scattering( DLS) and transmission electron microscopy( TEM). The polypeptide blocks were shown to exhibit α-helix conformations,and all copolymers could spontaneously self-assemble into sphere or rodlike micelles in aqueous or organic solution due to the different solubility of the distinct blocks. Such strategy offers a general and efficient way to achieve various amphiphlic hybrid copolymers using simple copolymer precursors,especially for the preparation of functional self-assembly materials with various architectures. Moreover,the self-assemblies of these functional amphiphilic copolypeptides could be easily modulated by tuning the optional macroinitiators and a series of functional thiols.