Fast Surface Crystallization of Amorphous Griseofulvin Below T g

Zhu, Lei; Jona, Janan; Nagapudi, Karthik; Wu, Tian Shung

doi:10.1007/s11095-010-0140-8

Cited by 94 publications

(108 citation statements)

References 28 publications

Supporting

Mentioning

102

Contrasting

Order By: Relevance

“…The results show higher degrees of crystallinity on the surface of the compacts that in ground compacts both using Raman and XRPD, indicating that the higher crystallinity detected using Raman could be due to the crystallization itself being more pronounced on the compact surface. Crystallization on the surface of amorphous particles has been reported to be considerably faster than in the bulk using griseofluvin, indomethacin and nifedipine (Zhu et al, 2010(Zhu et al, , 2008Wu et al, 2007;Wu and Yu, 2006) due to surface molecules having a higher mobility than molecules in the bulk. Zhu et al (2010Zhu et al ( , 2008 and Wu et al (2007) showed that surface crystallization could be suppressed by coating the sample surface.…”

Section: Recrystallization Of Xylitol and Xylitol-silica Solid Dispermentioning

confidence: 99%

“…Crystallization on the surface of amorphous particles has been reported to be considerably faster than in the bulk using griseofluvin, indomethacin and nifedipine (Zhu et al, 2010(Zhu et al, , 2008Wu et al, 2007;Wu and Yu, 2006) due to surface molecules having a higher mobility than molecules in the bulk. Zhu et al (2010Zhu et al ( , 2008 and Wu et al (2007) showed that surface crystallization could be suppressed by coating the sample surface. Nanubolu and Burley (2012) and Wu et al (2007) reported that the crystallization kinetics of amorphous drugs changed when covering the sample using a coverslip and thus restricting the surface molecule mobility.…”

Section: Recrystallization Of Xylitol and Xylitol-silica Solid Dispermentioning

confidence: 99%

“…It has been shown that the surface crystallization is more rapid than bulk crystallization in amorphous glasses aged below their glass transition temperature (Zhu et al, 2010(Zhu et al, , 2008Wu et al, 2007;Wu and Yu, 2006;Yu, 2016). The reason for this can not only be found in the higher molecular mobility of surface molecules compared to bulk molecules, but also in the more pronounced structural relaxation of the surface as compared to the bulk (Hasegawa et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Monitoring the recrystallisation of amorphous xylitol using Raman spectroscopy and wide-angle X-ray scattering

Palomäki

Ahvenainen

Ehlers

et al. 2016

International Journal of Pharmaceutics

View full text Add to dashboard Cite

Chemical compounds studied in this article: Xylitol (PubChem CID 6912) Silica (PubMed CID 24261) Ibuprofen (PubChem CID 3672) Indomethacin (PubChem CID 3715) Keywords:Amorphous Crystallization Raman spectrometry Wide-angle X-ray scattering Xylitol Non-ordered mesoporous silica A B S T R A C TIn this paper we present a fast model system for monitoring the recrystallization of quench-cooled amorphous xylitol using Raman spectroscopy and wide-angle X-ray scattering. The use of these two methods enables comparison between surface and bulk crystallization. Non-ordered mesoporous silica micro-particles were added to the system in order to alter the rate of crystallization of the amorphous xylitol. Raman measurements showed that adding silica to the system increased the rate of surface crystallization, while X-ray measurements showed that the rate of bulk crystallization decreased. Using this model system it is possible to measure fast changes, which occur in minutes or within a few hours. Raman-spectroscopy and wide-angle X-ray scattering were found to be complementary techniques when assessing surface and bulk crystallization of amorphous xylitol.

show abstract

Section: Recrystallization Of Xylitol and Xylitol-silica Solid Dispermentioning

confidence: 99%

Section: Recrystallization Of Xylitol and Xylitol-silica Solid Dispermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Monitoring the recrystallisation of amorphous xylitol using Raman spectroscopy and wide-angle X-ray scattering

Palomäki

Ahvenainen

Ehlers

et al. 2016

International Journal of Pharmaceutics

View full text Add to dashboard Cite

show abstract

“…Recent studies have discovered that different modes of crystal growth can emerge as a liquid is cooled to form a glass (3)(4)(5)(6)(7)(8), causing crystal growth fronts to advance at velocities much faster than predicted by standard theories. One such growth mode [the glass-to-crystal (GC) mode] exists in the bulk and can cause an increase of crystal growth rate by a factor of 10 4 with a temperature drop by a few kelvin (3,4).…”

mentioning

confidence: 99%

“…One such growth mode [the glass-to-crystal (GC) mode] exists in the bulk and can cause an increase of crystal growth rate by a factor of 10 4 with a temperature drop by a few kelvin (3,4). Another new growth mode occurs at the free surface and can lead to much faster crystal growth than in the bulk (5)(6)(7)(8). Although these phenomena have been observed prominently in organic glasses, they may be relevant for understanding glass crystallization in general.…”

mentioning

confidence: 99%

Glasses crystallize rapidly at free surfaces by growing crystals upward

Sun

Zhu

Kearns

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

126

137

View full text Add to dashboard Cite

The crystallization of glasses and amorphous solids is studied in many fields to understand the stability of amorphous materials, the fabrication of glass ceramics, and the mechanism of biomineralization. Recent studies have found that crystal growth in organic glasses can be orders of magnitude faster at the free surface than in the interior, a phenomenon potentially important for understanding glass crystallization in general. Current explanations differ for surface-enhanced crystal growth, including released tension and enhanced mobility at glass surfaces. We report here a feature of the phenomenon relevant for elucidating its mechanism: Despite their higher densities, surface crystals rise substantially above the glass surface as they grow laterally, without penetrating deep into the bulk. For indomethacin (IMC), an organic glass able to grow surface crystals in two polymorphs (α and γ), the growth front can be hundreds of nanometers above the glass surface. The process of surface crystal growth, meanwhile, is unperturbed by eliminating bulk material deeper than some threshold depth (ca. 300 nm for α IMC and less than 180 nm for γ IMC). As a growth strategy, the upward-lateral growth of surface crystals increases the system's surface energy, but can effectively take advantage of surface mobility and circumvent slow growth in the bulk. C rystallization is a ubiquitous process, producing countless solids in the natural and man-made world. Glasses and amorphous solids are formed by avoiding crystallization while cooling liquids, condensing vapors, or drying solutions. The solidity of a glass might suggest resistance to crystallization; its very existence implies that crystallization is avoidable. And yet glasses can crystallize, sometimes surprisingly fast. The crystallization of glasses is of interest in many fields for understanding the stability of amorphous materials (1), the fabrication of glass ceramics, and the mechanism of biomineralization, for which crystallization of amorphous solid precursors is considered a key step (2).Recent studies have discovered that different modes of crystal growth can emerge as a liquid is cooled to form a glass (3-8), causing crystal growth fronts to advance at velocities much faster than predicted by standard theories. One such growth mode [the glass-to-crystal (GC) mode] exists in the bulk and can cause an increase of crystal growth rate by a factor of 10 4 with a temperature drop by a few kelvin (3, 4). Another new growth mode occurs at the free surface and can lead to much faster crystal growth than in the bulk (5-8). Although these phenomena have been observed prominently in organic glasses, they may be relevant for understanding glass crystallization in general. These phenomena seem to have counterparts in nonorganic glasses, but differences are also evident. Fast crystal growth is known for metallic glasses and amorphous silicon, but the abrupt activation of GC growth is reported only for organic glasses. Surface-enhanced crystal growth occurs in amorphous selenium ...

show abstract

In situ AFM study of near‐surface crystallization in PET and PEN

Shinotsuka

Assender

2016

J of Applied Polymer Sci

View full text Add to dashboard Cite

The surface crystallization behavior of poly(ethylene terephthalate) (PET) and poly(ethylene 2,6-naphthalate) (PEN) spincoated thin films was compared by means of atomic force microscopy (AFM) with an in situ heating stage. As the films were heated up stepwise, characteristic surface crystals appeared at a crystallization temperature (T c ) in the near-surface region which is about 15 8C under the bulk T c , and were replaced by bulk crystals when the temperature was increased to the bulk T c . In the case of films whose thickness is less than 70 nm (PET) and 60 nm (PEN), significant increases in the bulk T c were observed. Scanning force microscopy (SFM) force-distance curve measurements showed that the glass transition temperature (T g ) of the near-surface region of PET and PEN were 22.0 and 26.6 8C below their bulk T g (obtained by DSC). After the onset of surface crystallization, edge-on and flat-on crystals appeared at the free surface of PET and PEN thin films, whose morphologies are very different to those of the bulk crystals. Although the same general behavior was observed for both polyesters, there are significant differences both the influence of the surface and substrate on the transition temperatures, and in morphology of the surface crystals. These phenomena are discussed in terms of the differences in the mobility of polymer chains near the surface.

show abstract

Fast Surface Crystallization of Amorphous Griseofulvin Below T g

Cited by 94 publications

References 28 publications

Monitoring the recrystallisation of amorphous xylitol using Raman spectroscopy and wide-angle X-ray scattering

Monitoring the recrystallisation of amorphous xylitol using Raman spectroscopy and wide-angle X-ray scattering

Glasses crystallize rapidly at free surfaces by growing crystals upward

In situ AFM study of near‐surface crystallization in PET and PEN

Contact Info

Product

Resources

About