The aim of this study was to show that atomic force microscopy (AFM) can be used to obtain mechanistic and kinetic information about the process of moisture-induced surface crystallization of single particles of amorphous lactose. Completely amorphous lactose particles were prepared by spray-drying a solution of alpha-lactose monohydrate, and moisture-induced crystallization was monitored for a bed of particles by microcalorimetry and for single particles by AFM. From the AFM images it was found that crystallization of the surface of single particles can be described in terms of a sequence of three events: an initial smoothening of the surface, formation of crystalline nanostructures dispersed in amorphous material, and growth of these structures to a complete crystalline surface. The surface roughness parameter rugosity was used to estimate the fraction crystalline surface, and the growth kinetics were found to obey the JMAK equation. The fraction crystalline surface at different times could also be estimated by determining the growth rate of individual crystals. It was concluded that AFM offers a unique means of visualizing the process of moisture-induced surface crystallization of amorphous particles and enables mechanistic and kinetic information about the process to be extracted.
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http://dx.doi.org/10.1002/jps.10503 | DOI Listing |
Angew Chem Int Ed Engl
January 2025
Sree Chitra Tirunal Institute for Medical Sciences and Technology, Bioceramics Division, Biomedical Technology Wing, 695011, Thiruvananthapuram, INDIA.
A collagen-inspired helical protein-mimic has been synthesized via topochemical polymerization of a designed tripeptide monomer. In the monomer crystal, molecules arrange in a head-to-tail manner, forming supramolecular helices. The azide and alkyne of adjacent molecules in the supramolecular helix are proximally preorganized in a ready-to-react arrangement.
View Article and Find Full Text PDFBiomaterials
May 2025
State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, 2999 North Renmin Road, Shanghai, 201620, China.
Moisture induced by wound exudate is crucial throughout the wound repair process. The dressing directly affects the absorption, permeation, and evaporation of the wound exudate. However, most dressings in clinical often result in excessive dryness or moisture of wound due to their monotonous structure and function, leading to ineffective thermodynamic control of evaporation enthalpy.
View Article and Find Full Text PDFAdv Mater
December 2024
Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, SE-106 91, Sweden.
Superinsulating nanofibrillar cellulose foams have the potential to replace fossil-based insulating materials, but the development is hampered by the moisture-dependent heat transport and the lack of direct measurements of phonon transport. Here, inelastic neutron scattering is used together with wide angle X-ray scattering (WAXS) and small angle neutron scattering to relate the moisture-dependent structural modifications to the vibrational dynamics and phonon transport and scattering of cellulose nanofibrils from wood and tunicate, and wood cellulose nanocrystals (W-CNC). The moisture interacted primarily with the disordered regions in nanocellulose, and WAXS showed that the crystallinity and coherence length increased as the moisture content increased.
View Article and Find Full Text PDFRSC Adv
December 2024
Department of Physics, Research Institute Physics and Chemistry, Jeonbuk National University Jeonju 54896 Republic of Korea
Adv Sci (Weinh)
December 2024
Key Laboratory of Polar Materials and Devices, Ministry of Education, Shanghai Center of Brain-inspired Intelligent Materials and Devices, East China Normal University, Shanghai, 200241, China.
The discovery of nanoscale ferroelectricity in hafnia (HfO) has paved the way for next generation high-density, non-volatile devices. Although the surface conditions of nanoscale HfO present one of the fundamental mechanism origins, the impact of external environment on HfO ferroelectricity remains unknown. In this study, the deleterious effect of ambient moisture is examined on the stability of ferroelectricity using HfZrO (HZO) films as a model system.
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