Unraveling the Complex Polymorphic Crystallization Behavior of the Alternating Copolymer DMDS-alt-DVE

Area of Science:

• Polymer Science and Engineering
• Materials Chemistry
• Crystallography

Background:

• Alternating copolymers like DMDS-alt-DVE are innovative polythioethers with potential in polymer coatings.
• Previous studies reported two crystalline phases (L-Tm and H-Tm) for DMDS-alt-DVE, with H-Tm requiring prior melting of L-Tm.
• Understanding the complex crystallization behavior and polymorphism is key to optimizing material properties.

Purpose of the Study:

• To thoroughly investigate the complex polymorphic behavior of the DMDS-alt-DVE alternating copolymer.
• To explore the interrelationships between different crystalline phases under various thermal conditions.
• To identify new polymorphic forms beyond those previously reported.

Main Methods:

• Calorimetric techniques were employed across seven orders of magnitude of scanning rates.
• Rapid quenching to sub-ambient temperatures was used to induce and detect novel crystalline phases.
• Tailored thermal protocols were designed to selectively produce samples with specific polymorph compositions.

Main Results:

• A previously unreported polymorphic form, characterized by a very low melting temperature (VL-Tm), was detected.
• The study successfully generated samples containing exclusively one, two, or all three identified polymorphs (VL-Tm, L-Tm, H-Tm).
• Insights into the interrelationships and formation pathways of these distinct crystalline phases were gained.

Conclusions:

• The DMDS-alt-DVE copolymer exhibits more complex polymorphism than previously understood, including a novel VL-Tm phase.
• Controlled thermal processing allows for the selective formation of specific polymorphs, enabling tailored material properties.
• A deeper understanding of polythioether polymorphism, crystallization, and morphology is critical for enhancing mechanical and barrier properties in applications like polymer coatings.