Intracrystalline Dynamics in Poly(3-hydroxybutyrate) and Its Role in Morphological Evolution and Mechanical Implications

Poly(3-hydroxybutyrate) (P3HB) is a semicrystalline biodegradable polymer that gradually becomes brittle upon aging, yet the molecular processes behind this transformation remain debated [1]. Here we investigate the role of intracrystalline chain mobility within the lamellar crystals of P3HB and how it influences the evolution of semicrystalline morphology and mechanical behavior [2]. Solid-state NMR reveals slow motions consistent with helical jumps of chains confined inside the crystalline lamellae, while SAXS and fast scanning calorimetry track morphological changes occurring under the same thermal conditions used in mechanical studies. The combined analysis suggests a connection between intracrystalline diffusion, secondary crystallization, and the progressive confinement of amorphous regions, which may underlie the well-known embrittlement of P3HB. This integrated approach links molecular-scale dynamics to long-term structural evolution and provides a physical basis for understanding and potentially mitigating the instability of semicrystalline biodegradable polymers.

References

[1] De Koning, G.J. M. & Lemstra, P. J., Polymer, 1993, 34, 4089.

[2] Anuar, A., et al., Macromolecules, 2024, 57, 8507.