Glass Transitions of Ethylene Oxide Polymers

Faucher, J. A.; Koleske, JV; Santee, E. R.; Stratta, J. J.; Wilson, C. W.

doi:10.1063/1.1707961

Cited by 143 publications

(76 citation statements)

References 15 publications

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“…By using broadline proton nuclear magnetic resonance, Faucher et al showed that T g of PEG increased from -49°C for PEG 400 to a maximum of -20°C for PEG 6000 and then decreased with molecular weight. 20 However, in the current study, dispersions containing IMC and PEG 6000 displayed T g s well below -20°C ( Figure 4), suggesting that the T g of pure PEG 6000 must be much lower than -20°C.…”

Section: Composition-dependent Glass Transition Temperature (T G ) Shmentioning

confidence: 77%

Crystallization Kinetics of Indomethacin/Polyethylene Glycol Dispersions Containing High Drug Loadings

2015

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The reproducibility and consistency of physicochemical properties and pharmaceutical performance are major concerns during preparation of solid dispersions. The crystallization kinetics of drug/polyethylene glycol solid dispersions, an important factor that is governed by the properties of both drug and polymer has not been adequately explored, especially in systems containing high drug loadings. In this paper, by using standard and modulated differential scanning calorimetry and X-ray powder diffraction, we describe the influence of drug loading on crystallization behavior of dispersions made up of indomethacin and polyethylene glycol 6000. Higher drug loading increases the amorphicity of the polymer and inhibits the crystallization of PEG. At 52% drug loading, polyethylene glycol was completely transformed to the amorphous state. To the best of our knowledge, this is the first detailed investigation of the solubilization effect of a low molecular weight drug on a semicrystalline polymer in their dispersions. In mixtures containing up to 55% indomethacin, the dispersions exhibited distinct glass transition events resulting from amorphous-amorphous phase separation which generates polymer-rich and drug-rich domains upon the solidification of supercooled polyethylene glycol, whereas samples containing at least 60% drug showed a single amorphous phase during the period in which crystallization normally occurs. The current study demonstrates a wide range in physicochemical properties of drug/polyethylene glycol solid dispersions as a result of the complex nature in crystallization of this system, which should be taken into account during preparation and storage.

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Section: Composition-dependent Glass Transition Temperature (T G ) Shmentioning

confidence: 77%

Crystallization Kinetics of Indomethacin/Polyethylene Glycol Dispersions Containing High Drug Loadings

2015

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“…[89] For example, ethylene glycol (n ¼ 1) exhibits a T g ¼ À93 8C, a value which increases to À50 8C when 9 ethylene oxide units are placed in the chain. The T g of monomer 9, possessing 4 ethylene oxide units, falls in an intermediate range (À75 8C), which was deemed Chain-End and Chain-Internal Crosslinking in ''Latent Reactive'' Silicon Elastomers sufficiently low for our study.…”

Section: Resultsmentioning

confidence: 99%

Chain‐End and Chain‐Internal Crosslinking in “Latent Reactive” Silicon Elastomers

Matloka

Sworen

Zuluaga

et al. 2005

Macro Chemistry & Physics

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Summary: Latent reactivity has been employed to create processable elastomers constructed of carbosilane and either carbosiloxane or polyether segments. Two types of latent modes have been introduced: “chain‐internal” and “chain‐end” sites through the use of labile silicon methoxy and trifunctional olefinic functionalities. These latent reactive sites remain inert during formation of the linear copolymer; subsequent exposure to moisture triggers hydrolysis of the methoxy group and formation of a chemically crosslinked thermoset. These “chain‐end” sites limit the formation of dangling chains improving the overall mechanical properties of the material. The thermoset's mechanical response can be potentially varied from plastic to elastic behavior, depending on the ratio of hard and soft monomers employed. The concentration of “chain‐internal” and “chain‐end” crosslink sites enhances strength; modification to the run length and structure of the soft phase enhances elasticity, generating samples having moduli of 6 MPa, tensile strengths of 0.6 MPa and elongations of 400%.“Latent reactive” silicon elastomer.magnified image“Latent reactive” silicon elastomer.

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“…With convenient geometrical alignment of its polymer chains, PEO is a semicrystalline material with a reported crystallinity as high as 72% and a melting point in the range of 60-75 C. 27 The Tg of the amorphous regions of PEO has been reported to be À53 C. 28 With a rigid structure and a bulky carboxyl side group, PAA can only exist in an amorphous form. DSC profiles of the physical blend and IPC of Polyox N12K and Carbopol 907 are presented in Figure 5.…”

Section: Properties Of the Ipc Between Polyox N12k And Carbopol 907mentioning

confidence: 99%

Interpolymer Complexation Between Polyox and Carbopol, and Its Effect on Drug Release From Matrix Tablets

Zhang

Lubach²,

et al. 2016

Journal of Pharmaceutical Sciences

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Glass Transitions of Ethylene Oxide Polymers

Cited by 143 publications

References 15 publications

Crystallization Kinetics of Indomethacin/Polyethylene Glycol Dispersions Containing High Drug Loadings

Crystallization Kinetics of Indomethacin/Polyethylene Glycol Dispersions Containing High Drug Loadings

Chain‐End and Chain‐Internal Crosslinking in “Latent Reactive” Silicon Elastomers

Interpolymer Complexation Between Polyox and Carbopol, and Its Effect on Drug Release From Matrix Tablets

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