Stimuli-responsive peptide-based ABA-triblock copolymers: unique morphology transitions with pH

Area of Science:

• Polymer Chemistry
• Materials Science
• Supramolecular Chemistry

Background:

• Polymeric micelles are crucial self-assembled nanostructures with tunable properties.
• Block copolymers offer versatile platforms for creating complex architectures like micelles and vesicles.
• Understanding the influence of block composition and pH on morphology is key for designing functional materials.

Purpose of the Study:

• To synthesize and characterize poly(L-lysine)-b-poly(propylene oxide)-b-poly(L-lysine) (KPK) triblock copolymers.
• To investigate the pH-dependent morphology transitions of KPK copolymers.
• To correlate copolymer composition and charge state with observed self-assembled structures.

Main Methods:

• Synthesis of KPK triblock copolymers with high lysine weight fractions.
• Solution characterization using light-scattering techniques.
• Morphology analysis via microscopy (e.g., TEM, AFM).

Main Results:

• KPK triblock copolymers exhibit distinct morphology transitions with changing pH.
• Spherical micelle-vesicle and spherical micelle-disk micelle transitions were observed.
• Morphology changes are attributed to the balance between core block folding energy and charged block interfacial curvature.

Conclusions:

• KPK triblock copolymers demonstrate pH-responsive self-assembly behavior.
• The observed morphology transitions are governed by thermodynamic principles related to polymer block interactions.
• These findings provide insights into the design of stimuli-responsive polymeric nanostructures.