The thermodynamics of glycollide, polyglycollide and of polymerization of glycollide in the temperature range of 0–550°K

Yevstropov, A.A.; Kiparisova, Ye.G.; Belov, V.I.

doi:10.1016/0032-3950(78)90109-0

Cited by 21 publications

(21 citation statements)

References 7 publications

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“…Lebedev and co-workers 31 previously reported ∆ f H°m(PGA, pol) ) -(367.2 ( 0.8) kJ‚mol -1 for a PGA sample with 100% crystallinity and ∆ f H°m(PGA, pol) ) -(355.6 ( 1.3) kJ‚mol -1 for an amorphous PGA sample, both prepared by ring opening polymerization and with average chain lengths in the range of 36000-52000 monomers. Note, however, that the three results are not directly comparable.…”

Section: Resultsmentioning

confidence: 96%

“…The difference between ∆ r H°m (15) obtained in this work and the corresponding differential scanning calorimetry data in Table 4 is not likely to be significantly changed by correcting the DSC results to 298.15 K. In fact, using C°p ,m (ClCH 2 COONa, cr) ) 114. 31 and C°p ,m (NaCl, cr) ) 50.509 J‚K -1 ‚mol -1 . 42 The enthalpy of reaction 2, which refers to a polymer with a number of monomers large enough to make the enthalpic contribution of the endgroups negligible, can also be calculated, at 298.15 K, by using the ∆ f H m o (PGA, pol) values for 100% crystalline (PGA-100%cr) and fully amorphous (PGA-am) polymer, reported by Lebedev and co-workers, 31 and quoted above.…”

Section: Resultsmentioning

confidence: 99%

“…They were further recrystallized from ethanol/water (50:50 v/v), dried in vacuum (100 Pa), and kept in Schlenk tubes under argon prior to the calorimetric experiments. All samples were characterized by IR, 1 crystallinity was estimated as 62% from the ratio of the ∆ fus H m value quoted above to the mean value ∆ fus H m ) 11.86 kJ‚mol -1 of the enthalpies of fusion of fully crystalline PGA reported by Lebedev et al 31 and Ginde et al 32 Viscometry gave an average chain length of 27 monomers, based on a molar mass of the monomer of 58 g‚mol -1 . The As 2 O 3 aqueous solution used in the combustion calorimetric experiments was prepared by dissolving solid As 2 O 3 (B. D. H.; mass fraction 0.998) in boiling distilled and deionized water.…”

Section: Methodsmentioning

confidence: 99%

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Driving Force for the Thermally Induced Solid State Polymerization of Alkali Metal Halogenoacetates: A Thermochemical Analysis

Lagoa¹,

Diogo²,

Piedade³

et al. 2002

J. Phys. Chem. B

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Reaction-solution calorimetry was used to determine the standard molar enthalpies of formation of a series of lithium and sodium halogenoacetates in the crystalline state at 298.15 K. The obtained values were as follows: 740.9 ( 0.7) kJ‚mol -1 , ∆ f H°m(BrCH 2 COONa, cr) ) -(700.2 ( 1.2) kJ‚mol -1 , and ∆ f H°m(ICH 2 COONa, cr) ) -(642.0 ( 1.6) kJ‚mol -1 . Microcombustion calorimetric studies of a polyglycolide sample with the empirical formula C 2.000 H 2.160 O 2.032 Cl 0.009243 Na 0.004404 (PGA) led to ∆ f H°m(PGA, pol) ) -( 379.1 ( 1.1) kJ‚mol -1 . These results were used to discuss the energetics of the solid-state polymerization of alkali metal halogenoacetates leading to polyglycolide. In agreement with experimental observations, it is concluded that for a given metal, the reaction becomes less favorable when the halogen changes along the series Cl f Br f I. The reaction is also considerably less favorable for the lithium than for the homologue sodium salts. These differences in reactivity seem to be mainly determined by the lattice enthalpy of the alkali metal halide salt formed in each reaction.

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Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Driving Force for the Thermally Induced Solid State Polymerization of Alkali Metal Halogenoacetates: A Thermochemical Analysis

Lagoa¹,

Diogo²,

Piedade³

et al. 2002

J. Phys. Chem. B

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“…25 Using the bulk heat of fusion for poly(glycolide), which was reported to be 11.96 KJ * (mol monomer) Ϫ1 for 100% crystalline poly(glycolide) 26 or 11.75 KJ * (mol monomer) Ϫ1 , 27 the PLGA "crystallinity" in our gel systems was estimated to be around 7-8% of the total glycolide units. However, the "crystallites" in the gels are small because of the low molecular weight of the glycolide segment and because of the presence of solvent molecules.…”

Section: Differential Scanning Calorimetry (Dsc) Observationsmentioning

confidence: 99%

Structure formation in injectable poly(lactide‐co‐glycolide) depots. II. Nature of the gel

et al. 2004

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The benzyl benzoate solutions of poly(D,L-lactide-co-glycolide), a random oriented synthesized copolymer with L/G ratio of 50:50, have been shown to form gels during aging and upon injection into buffer or water. The gelation properties influence drug release kinetics for these injectable, depot-forming solutions. In this article, we report on the mechanism of gelation. We find that only polymers that have a certain average block length of glycolide units form gels during aging as well as depots upon in vitro. Thus, gel formation is likely due to the formation of ordered solvated aggregates of blocky glycolide units. Rheometry, differential scanning calorimetry, and nuclear magnetic resonance were used to investigate the gelation kinetics and the polymer molecular parameters. Of all the polymers used, poly(lactide-coglycolide)s with glycolide average block length <2.9 did not show any gelation behavior. The details of the gelation process are also solvent dependent.

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“…Note, for example, the different relative intensities of the peak at 170 °C in the inset of Figure a. The high melting temperatures are associated with the fusion of polyglycolide hard segments (i.e., 229 °C is the reported equilibrium melting temperature of polyglycolide) and its enthalpy allowed the crystallinity of the sample to be estimated considering a value of 11.8 kJ mol −1 for a 100% crystalline polyglycolide . Crystallinities of 22% and 21% were thus determined for the as processed scaffold and the melt crystallized sample (Figure b), respectively.…”

Section: Resultsmentioning

confidence: 99%

Tunable Drug Loading and Reinforcement of Polycaprolactone Films by Means of Electrospun Nanofibers of Glycolide Segmented Copolymers

Márquez

Franco

Turón

et al. 2017

Macro Materials & Eng

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Electrospinning of a segmented copolymer having polyglycolide hard segments is successfully performed from 1,1,1,3,3,3‐hexafluoroisopropanol solutions. During the process, a bactericidal agent, i.e., chlorhexidine (CHX), is effectively loaded, which results in nanofibers with a smaller diameter because of the change in solution conductivity. New fabrics based on molding of alternate layers of poly(ε‐caprolactone) (PCL) films and the electrospun scaffolds of the segmented copolymer are prepared and characterized. The thermal molding process renders a PCL matrix homogeneously reinforced with nanofibers that compensate for the loss of mechanical properties caused by incorporation of CHX. Release of CHX is evaluated in different media. Results vary depending on the layer where the drug is incorporated. Thus, systems with an immediate bacteriostatic effect, as well as systems with a potential long term antimicrobial effect, are obtained. Growth inhibition and adhesion assays demonstrate the fast bactericidal effect of samples with CHX loaded in its outer layers.

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The thermodynamics of glycollide, polyglycollide and of polymerization of glycollide in the temperature range of 0–550°K

Cited by 21 publications

References 7 publications

Driving Force for the Thermally Induced Solid State Polymerization of Alkali Metal Halogenoacetates: A Thermochemical Analysis

Driving Force for the Thermally Induced Solid State Polymerization of Alkali Metal Halogenoacetates: A Thermochemical Analysis

Structure formation in injectable poly(lactide‐co‐glycolide) depots. II. Nature of the gel

Tunable Drug Loading and Reinforcement of Polycaprolactone Films by Means of Electrospun Nanofibers of Glycolide Segmented Copolymers

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