Solid-state multipulse proton Nuclear Magnetic Resonance (NMR) characterization of self-assembling polymer films

Area of Science:

• Polymer Science
• Materials Science
• Solid-State Physics

Background:

• Poly(styrene-b-isoprene-b-styrene) triblock copolymers exhibit complex self-assembled structures.
• Understanding domain morphology is crucial for tailoring material properties.
• Solid-state Nuclear Magnetic Resonance (NMR) offers non-destructive methods for structural analysis.

Purpose of the Study:

• To investigate the domain structure of poly(styrene-b-isoprene-b-styrene) triblock copolymers.
• To compare domain sizes in clear films versus self-assembled films with microcavities.
• To determine the influence of film preparation on nanoscale domain morphology.

Main Methods:

• Multipulse solid-state proton Nuclear Magnetic Resonance (NMR) spectroscopy.
• Proton spin diffusion measurements utilizing a dipolar filter pulse sequence.
• Preparation of polymer films via solvent casting (carbon disulfide in moist environment and solvent evaporation under nitrogen).

Main Results:

• Domain sizes for polystyrene and polyisoprene blocks were measured in the range of 3-6 nm.
• Domain sizes were found to be dependent on the polymer molecular weight.
• No significant differences in domain size were observed between clear films and self-assembled films with microcavities.

Conclusions:

• Solid-state proton NMR is effective for characterizing nanoscale domain structures in block copolymers.
• The preparation method (clear vs. self-assembled films) does not significantly alter the fundamental domain sizes.
• The observed domain sizes are consistent with established polymer self-assembly principles.