Regensburg 2025 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 32: Poster Session II

CPP 32.28: Poster

Thursday, March 20, 2025, 09:30–12:00, P3

Morphology and intracrystalline dynamics of semicrystalline polyester Poly(3-hydroxy-2,2-dimethylbutyrate) — •Johann C. Holz¹, Arman Edalat¹, Kay Saalwächter¹, Thomas Thurn-Albrecht¹, and Eugene Chen² — ¹Martin-Luther-University, Halle, GER — ²Colorado State University, Fort Collins, USA

Semicrystalline polymers are classified as crystal-fixed (non-diffusive) or crystal-mobile (diffusive) based on polymer chain mobility within the crystal. Crystal-fixed polymers exhibit lower crystallinity, thinner lamellae (da>dc), and less variation in thickness (σa>σc). Finding a biodegradable alternative for crystal-mobile polyethylene (PE) remains a priority for sustainable research. Poly(3-hydroxybutyrate) (P3HB), a biodegradable polyester, was recently found to be crystal-mobile, but suffers from poor mechanical properties.

We here study Poly(3-hydroxy-2,2-dimethylbutyrate) (P3H(Me)2B), a structurally similar polyester with methyl-groups substituted for the two α-hydrogens, to improve mechanical toughness, thermal stability, and recyclability. Our analysis of P3H(Me)2B by Small-Angle X-ray Scattering (SAXS) revealed that it crystallizes in a crystal-fixed mode. This finding contrasts with the crystal-mobile behavior observed in P3HB. Wide-Angle X-ray Scattering (WAXS) corroborated the crystal structure that has already been described in literature, while also revealing previously undetected diffraction peaks. Furthermore, Nuclear Magnetic Resonance (NMR) spectroscopy enabled precise quantification of the polymer’s crystallinity, facilitating accurate determination of the melting enthalpy Hf for a 100% crystalline sample.

Keywords: Crystallization; Polyester; SAXS; Intracrystalline Chain Dynamics; Interface Distribution Function