Physics of amorphous solids

Hilden, Lori R.; Morris, Kenneth R.

doi:10.1002/jps.10489

Cited by 153 publications

(85 citation statements)

References 36 publications

(41 reference statements)

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“…3 B). In case of SD systems (binary and ternary), all XRPD spectra showed the amorphous nature as there were no diffraction peaks observed for any SD; instead, a halo pattern attributed to the amorphous form was observed (12,15,32) (Fig. 3 D-I).…”

Section: X-ray Powder Diffraction Studiesmentioning

confidence: 96%

Physicochemical Investigations and Stability Studies of Amorphous Gliclazide

Jondhale¹,

Bhise²,

Pore³

2012

AAPS PharmSciTech

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Abstract. Gliclazide (GLI), a poorly water-soluble antidiabetic, was transformed into a glassy state by melt quench technique in order to improve its physicochemical properties. Chemical stability of GLI during formation of glass was assessed by monitoring thin-layer chromatography, and an existence of amorphous form was confirmed by differential scanning calorimetry and X-ray powder diffractometry. The glass transition occurred at 67.5°C. The amorphous material thus generated was examined for its in vitro dissolution performance in phosphate buffer (pH 6.8). Surprisingly, amorphous GLI did not perform well and was unable to improve the dissolution characteristics compared to pure drug over entire period of dissolution studies. These unexpected results might be due to the formation of a cohesive supercooled liquid state and structural relaxation of amorphous form toward the supercooled liquid region which indicated functional inability of amorphous GLI from stability point of view. Hence, stabilization of amorphous GLI was attempted by elevation of T g via formation of solid dispersion systems involving comprehensive antiplasticizing as well as surface adsorption mechanisms. The binary and ternary amorphous dispersions prepared with polyvinylpyrrolidone K30 (as antiplasticizer for elevation of T g ) and Aerosil 200® and/or Sylysia® 350 (as adsorbent) in the ratio of 1:1:1 (w/w) using kneading and spraydrying techniques demonstrated significant enhancement in rate and extent of dissolution of drug initially. During accelerated stability studies, ternary systems showed no significant reduction in drug dissolution performance over a period of 3 months indicating excellent stabilization of amorphous GLI.

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Section: X-ray Powder Diffraction Studiesmentioning

confidence: 96%

Physicochemical Investigations and Stability Studies of Amorphous Gliclazide

Jondhale¹,

Bhise²,

Pore³

2012

AAPS PharmSciTech

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“…Amorphous materials lacks the long‐range ordering of a crystal but has certain short‐range ordering at atomic length scale due to their favorable chemical bonding 142, 143. Due to the lack of three‐dimensional long‐range order, amorphous solids do not constructively diffract X‐rays, as do crystalline solids.…”

Section: Single‐phosphate Materials For Na Storagementioning

confidence: 99%

“…Due to the lack of three‐dimensional long‐range order, amorphous solids do not constructively diffract X‐rays, as do crystalline solids. Therefore, broad, diffuse haloes are observed in X‐ray powder diffraction patterns instead of well‐defined peaks 143. Amorphous solids are supposed as potential electrodes considering less lattice pressure during electrochemical reaction.…”

Section: Single‐phosphate Materials For Na Storagementioning

confidence: 99%

Phosphate Framework Electrode Materials for Sodium Ion Batteries

et al. 2017

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Sodium ion batteries (SIBs) have been considered as a promising alternative for the next generation of electric storage systems due to their similar electrochemistry to Li‐ion batteries and the low cost of sodium resources. Exploring appropriate electrode materials with decent electrochemical performance is the key issue for development of sodium ion batteries. Due to the high structural stability, facile reaction mechanism and rich structural diversity, phosphate framework materials have attracted increasing attention as promising electrode materials for sodium ion batteries. Herein, we review the latest advances and progresses in the exploration of phosphate framework materials especially related to single‐phosphates, pyrophosphates and mixed‐phosphates. We provide the detailed and comprehensive understanding of structure–composition–performance relationship of materials and try to show the advantages and disadvantages of the materials for use in SIBs. In addition, some new perspectives about phosphate framework materials for SIBs are also discussed. Phosphate framework materials will be a competitive and attractive choice for use as electrodes in the next‐generation of energy storage devices.

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“…This can be achieved by altering the crystal form (polymorph, hydrates/solvates) or by producing the amorphous form. The most common technique for producing an amorphous phase in pharmaceutical systems is mechanical activation (energization) of a crystalline mass by micronization (particle size reduction) (3), and the habit effects on solubility are transient and are influenced directly by particle size (1). Thus, solid dispersion systems existing as amorphous phase due to particle size reduction up to molecular or colloidal level could have maximum effect on solubility enhancement and hence, it was focused to obtain amorphous molecular dispersions of the drug, acetazolamide having poor lipophilicity (log P=0.14) in the present study.…”

Section: Introductionmentioning

confidence: 99%

Effectiveness of Spray Congealing to Obtain Physically Stabilized Amorphous Dispersions of a Poorly Soluble Thermosensitive API

Kulthe

Chaudhari

2014

AAPS PharmSciTech

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Abstract. An amorphous phase produced by micronization up to the molecular or colloidal level of a poorly soluble drug having low lipophilicity can distinctly enhance its solubility characteristics. However, though dispersing the molten mass of a poorly water-soluble drug within polymeric matrix has been found to be most effective in formation of molecular dispersions, the drug molecules which melt at high temperature also accompanied by decomposition, such as acetazolamide, are difficult to formulate as molecular dispersions. Hence, a method is proposed to obtain molecular dispersions of acetazolamide with poloxamer-237 by spray congealing under optimal heat treatment. Uniform molecular and/or colloidal dispersions of the drug were achieved with instantaneous solvent evaporation by mixing a drug solution with molten mass of the plasticizer matrix. Immobilization of dispersed drug molecules was effected subsequently through rapid solidification by spray congealing. Initial characterization of 1:1, 1:1.5, and 1:2 ratios of solid dispersions and devitrification study of an optimized (1:2) ratio ensured efficacy of the proposed method in formation of physically stabilized amorphous systems without thermal degradation and hence resulted in more than ninefold rise in solubility and more than 90% dissolution within initial 10 min. With 1:2 ratio, molecular dispersions could be achieved by initial solvent evaporation stage, which when subjected to spray congealing produced physically stable amorphous systems, without signs of thermal degradation. This study also proposes an opportunity for selection of those polymers with which the drug is immiscible in their fluid state, yet obtaining molecular dispersions.

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Physics of amorphous solids

Cited by 153 publications

References 36 publications

Physicochemical Investigations and Stability Studies of Amorphous Gliclazide

Physicochemical Investigations and Stability Studies of Amorphous Gliclazide

Phosphate Framework Electrode Materials for Sodium Ion Batteries

Effectiveness of Spray Congealing to Obtain Physically Stabilized Amorphous Dispersions of a Poorly Soluble Thermosensitive API

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