Low T_g, strongly segregated, ABA triblock copolymers: a rheological and structural study

Area of Science:

• Polymer Science
• Materials Science
• Organic Chemistry

Background:

• ABA triblock copolymers form reversible networks via microphase separation.
• High temperatures typically degrade the mechanical properties of these copolymers.
• Maintaining microphase separation at elevated temperatures is crucial for advanced applications.

Purpose of the Study:

• To design and synthesize ABA triblock copolymers with enhanced thermal stability.
• To investigate the effect of fluorination on microphase separation and thermal properties.
• To explore the relationship between copolymer architecture and mechanical performance at high temperatures.

Main Methods:

• Synthesis of poly(n-butyl acrylate)-poly(heptafluorobutyl acrylate)-poly(n-butyl acrylate) (PnPBA-PHFBA-PnBBA) triblock copolymers.
• Temperature-dependent Small-Angle X-ray Scattering (SAXS) to assess microphase separation.
• Linear shear rheology to evaluate mechanical properties and network behavior.

Main Results:

• Fluorination significantly increased block incompatibility, leading to strong segregation.
• Microphase separation was preserved up to high temperatures, overcoming typical degradation.
• Rheology revealed a temperature-stable plateau, dependent on block lengths, indicating robust network formation.

Conclusions:

• All-soft ABA triblock copolymers with fluorinated outer blocks offer superior thermal stability.
• The enhanced incompatibility and segregation enable high-temperature performance.
• Copolymer block length is a critical factor in tuning mechanical properties and thermal resistance.