Controlling internal pore sizes in bicontinuous polymeric nanospheres

Area of Science:

• Polymer Chemistry
• Materials Science
• Nanotechnology

Background:

• Amphiphilic block copolymers self-assemble into various nanostructures in solution.
• Controlling the internal morphology of these nanostructures is crucial for applications.
• Complex polymeric nanospheres offer unique possibilities for advanced material design.

Purpose of the Study:

• To synthesize complex polymeric nanospheres in water from comb-like amphiphilic block copolymers.
• To investigate the influence of polymer molecular weight and composition on internal morphology.
• To establish criteria for the formation of bicontinuous polymer nanospheres (BPNs) and control their size and pore characteristics.

Main Methods:

• Synthesis of comb-like amphiphilic block copolymers.
• Formation of nanospheres in aqueous solutions.
• Three-dimensional cryo-electron tomographic analysis for internal morphology determination.
• Construction of a partial phase diagram.
• Tuning of preparation parameters (solvent ratio) and copolymer properties (MW, hydrophilic fraction).

Main Results:

• Complex polymeric nanospheres were successfully formed in water.
• Polymer molecular weight and hydrophilic weight fraction precisely controlled internal structure.
• Criteria for bicontinuous polymer nanosphere (BPN) formation were identified (MW ≤ 17 kDa, hydrophilic fraction ≤ 0.25).
• Nanosphere diameters were tunable from 70 to 460 nm by varying the organic solvent to water ratio.
• Internal pore diameters of BPNs were controlled from 10 to 19 nm by adjusting the hydrophilic-hydrophobic balance.

Conclusions:

• Comb-like amphiphilic block copolymers are effective building blocks for complex nanospheres in water.
• Precise control over nanosphere size and internal pore structure is achievable by tuning copolymer properties and preparation conditions.
• The findings provide a framework for designing BPNs with tailored morphologies for specific applications.