Molecular Motions in Sucrose-PVP and Sucrose-Sorbitol Dispersions—II. Implications of Annealing on Secondary Relaxations

Bhattacharya, Sisir; Bhardwaj, Sunny P.; Suryanarayanan, Raj

doi:10.1007/s11095-014-1379-2

Cited by 4 publications

(2 citation statements)

References 27 publications

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“…Since sucrose hydrogen bonds with PVP, even a low PVP concentration can effectively inhibit crystallization. Furthermore, sucrose-PVP systems have also been the subject of numerous studies and have been comprehensively characterized. − Therefore, it was possible to systematically study the effect of numerous factors of interest, specifically plasticization, polymer concentration, compression pressure, and dwell time on its crystallization behavior.…”

Section: Introductionmentioning

confidence: 99%

Compression-Induced Crystallization in Sucrose-Polyvinylpyrrolidone Amorphous Solid Dispersions

Bērziņš

Suryanarayanan

2018

Crystal Growth & Design

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Tablets of amorphous sucrose and sucrosepolyvinylpyrrolidone (PVP) amorphous solid dispersions were compressed at 25, 75, or 150 MPa at dwell times ranging from 5 to 900 s. Compression-induced physical destabilization was evident from differential scanning calorimetry. Crystallization kinetics was monitored using a laboratory source X-ray diffractometer, while crystallization was detected using highly sensitive synchrotron radiation. At the highest compression pressure, sucrose crystallization was evident immediately after compression. However, the addition of PVP, even at a low concentration of 1% w/w, inhibited crystallization. Furthermore, nucleation itself was completely prevented at higher PVP concentrations (≥15% w/w) under a compression pressure of practical interest (150 MPa with 5 s dwell time). However, an increase in dwell time (e.g., to 60 s) facilitated nucleation, and there was an increase in nucleation density as a function of dwell time. Both polymer content and sample history were pivotal factors limiting compression-induced crystallization in plasticized amorphous systems. Generally, plasticization was found to amplify compression-induced destabilization. PVP, in a concentration dependent manner, attenuated this effect.

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Section: Introductionmentioning

confidence: 99%

Compression-Induced Crystallization in Sucrose-Polyvinylpyrrolidone Amorphous Solid Dispersions

Bērziņš

Suryanarayanan

2018

Crystal Growth & Design

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“…In light of its potential correlation with physical instability, molecular mobility in the amorphous state has been extensively investigated. − Many studies on the stability of solid dispersions have focused on the glass transition temperature ( T g ), with the goal of raising T g by the addition of a polymer. ,, Since amorphous systems are often characterized by multiple relaxations, T g alone does not provide a comprehensive picture of the molecular mobility. , Moreover, temperature dependence of molecular mobility in the glassy and supercooled liquid regions could be very different. − These characteristics are not reflected by T g , making it an unreliable indicator of molecular mobility. Thus, it is important to comprehensively study the molecular dynamics in the amorphous state.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of Amorphous Itraconazole Stabilization in Polymer Solid Dispersions: Role of Molecular Mobility

et al. 2014

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Physical instability of amorphous solid dispersions can be a major impediment to their widespread use. We characterized the molecular mobility in amorphous solid dispersions of itraconazole (ITZ) with each polyvinylpyrrolidone (PVP) and hydroxypropylmethylcellulose acetate succinate (HPMCAS) with the goal of investigating the correlation between molecular mobility and physical stability. Dielectric spectra showed two mobility modes: α-relaxation at temperatures above the glass transition temperature (Tg) and β-relaxation in the sub-Tg range. HPMCAS substantially increased the α-relaxation time, with an attendant increase in crystallization onset time and a decrease in crystallization rate constant, demonstrating the correlation between α-relaxation and stability. The inhibitory effect on α-relaxation as well as stability was temperature dependent and diminished as the temperature was increased above Tg. PVP, on the other hand, affected neither the α-relaxation time nor the crystallization onset time, further establishing the link between α-relaxation and crystallization onset in solid dispersions. However, it inhibited the crystallization rate, an effect attributed to factors other than mobility. Interestingly, both of the polymers acted as plasticizers of β-relaxation, ruling out the latter's involvement in physical stability.

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Orientational glass, orientationally disordered crystal and crystalline polymorphism: A further study on the thermal behavior and molecular mobility in levoglucosan

Ramos

2019

Journal of Molecular Liquids

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Molecular Motions in Sucrose-PVP and Sucrose-Sorbitol Dispersions—II. Implications of Annealing on Secondary Relaxations

Abstract: An increase in local mobility of sucrose brought about by annealing could be negated with an additive.

Cited by 4 publications

References 27 publications

Compression-Induced Crystallization in Sucrose-Polyvinylpyrrolidone Amorphous Solid Dispersions

Compression-Induced Crystallization in Sucrose-Polyvinylpyrrolidone Amorphous Solid Dispersions

Mechanism of Amorphous Itraconazole Stabilization in Polymer Solid Dispersions: Role of Molecular Mobility

Orientational glass, orientationally disordered crystal and crystalline polymorphism: A further study on the thermal behavior and molecular mobility in levoglucosan

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