The Journal of Physical Chemistry B · 2010 · 106 citations · 19 references
Natural SciencesChemistryMaterials ScienceMaterials ChemistryPolymer ChemistryPolymer MaterialsPolymer CharacterizationPolymer Physical ChemistryPolymer PhysicsPolymer StructurePolymerization ProcessesRaman SpectroscopyCrystallization MechanismsHigh-pressure Phase TransitionsHydrogen Bonding InteractionsIn Situ Raman SpectroscopyPolymer Molecular CharacteristicsPolymerization Mechanism AnalysisResonance Raman SpectroscopySpectroscopic Characterization
We report here the first in-situ Raman spectroscopic study of pressure-induced structural and polymeric transformations of acrylic acid. Two crystalline phases (I and II) were observed upon compression to approximately 0.3 and approximately 2.7 GPa. Phase I can be characterized with a single s-cis molecular conformation with possibly a similar structure to the low-temperature phase, while phase II suggests significantly enhanced molecular interactions toward polymerization and structural disordering. Beyond approximately 8 GPa, spectroscopic features indicate the onset of polymerization. The high-pressure polymeric phase together with the pressure-quenched materials was examined and compared with two commercial acrylic acid polymers using Raman spectroscopy. The characteristics of polymeric acrylic acid and their transformation mechanisms as well as the implications of hydrogen-bonding interactions are discussed.
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High-pressure synthesis of crystalline polyethylene using optical catalysis
David Chelazzi, Matteo Ceppatelli, Mario Santoro et al. · Nature Materials · 2004 · 112 citations