Journal Article

PUBDB-2025-02342

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Insights into Mechanochemical Solid-State Ball-Milling Reaction: Monitoring Transition from Heterogeneous to Homogeneous Conditions

Go, E. S. ; Hong, E. J. ; Lee, J. Y. ; Stolar, T.Extern* ; Peterson, G. I. ; Emmerling, F. L.Extern* ; Kim, K. (Corresponding author) ; Kim, J. G. (Corresponding author)

2025
ACS Publications Washington, DC

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Please use a persistent id in citations: doi:10.1021/jacsau.5c00322  doi:10.3204/PUBDB-2025-02342

Abstract: As mechanochemical synthesis has advanced significantly, there has been intense interest in understanding the underlying mechanisms of these reactions. Given that many mechanochemical processes are conducted in the solid-state without solvation yet sometimes yield faster reactions than those in solution, we sought to address the following question: Are mechanochemical reactions homo- or heterogeneous? To investigate, we employed a model system involving the mixing and copolymerization of l-lactide (LLA) and d-lactide (DLA), monitored through powder X-ray diffraction (PXRD), nuclear magnetic resonance, and differential scanning calorimetry. In situ and ex situ PXRD analyses of the mixture of LLA and DLA showed that vibratory ball milling rapidly transformed the initially heterogeneous lactide mixture into a homogeneous phase within one min due to collisions between the balls and the jar. By varying the milling conditions, we were able to regulate the level of mixing, which subsequently influenced the copolymerization outcomes. In the solid-state ball-milling copolymerization of LLA and DLA in the presence of a catalyst and initiator, multiblock copolymers of poly(l-lactic acid) and poly(d-lactic acid) were formed within one min during the early stage of the reaction, when incomplete mixing of the monomers led to a process governed by phase heterogeneity. In contrast, prolonged polymerization promoted conditions approaching homogeneity, ultimately yielding atactic poly(lactic acid). This transition from heterogeneous to homogeneous reactions is a distinctive feature compared to conventional homogeneous reactions, potentially leading to mechano-exclusive reaction designs.

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Contributing Institute(s):

1. DOOR-User (DOOR ; HAS-User)

Research Program(s):

1. 6G3 - PETRA III (DESY) (POF4-6G3) (POF4-6G3)
2. FS-Proposal: I-20231186 (I-20231186) (I-20231186)

Experiment(s):

1. PETRA Beamline P02.1 (PETRA III)

Appears in the scientific report 2025

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Database coverage:
; ; ; ; Article Processing Charges ; Clarivate Analytics Master Journal List ; DOAJ Seal ; Emerging Sources Citation Index ; Fees ; IF >= 5 ; JCR ; SCOPUS ; Web of Science Core Collection

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