Effect of hydrolytic degradation and dehydration on the microstructure of 50:50 poly(glycolide-co-D,L-lactide)

King, Elizabeth F.; Cameron, Ruth E.

doi:10.1002/(sici)1097-0126(199803)45:3<313::aid-pi936>3.0.co;2-r

Cited by 3 publications

(5 citation statements)

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“…The latter factor is known to remarkably enhance the hydrolytic degradation of the LA‐based polymer specimens in the core part 14,15,40. Hyon et al also observed that the weight loss rate of P(LLA‐DLA‐GA) specimens increased with the increase of GA unit content 19. The weight loss of the PLLA and P(LLA‐DLA) films remained almost unchanged for 24 weeks, in agreement with that of PLLA and P(LLA‐DLA)(50/50) films reported by Tsuji 26…”

Section: Resultsmentioning

confidence: 98%

“…During the last three decades, numerous articles have been published on hydrolytic degradation behavior of poly[( L ‐lactide)‐ co ‐glycolide] [P(LLA‐GA)], poly[( DL ‐lactide)‐ co ‐glycolide] [P(DLLA‐GA)], poly[( L ‐lactide)‐ co ‐( D ‐lactide)‐ co ‐glycolide] [P(LLA‐DLA‐GA)] and poly[( L ‐lactide)‐ co ‐( D ‐lactide)] [P(LLA‐DLA)] 13–25. Their in vitro degradation was traced by the changes in molecular weight13–15,17–20,22–25 and thermal properties 13–15,17,18,20,24,25. The crystallization of P(LLA‐DLA‐GA)(37.5/37.5/25), P(LLA‐GA)(75/25),15 and P(LLA‐GA)(10/90)24,25 occurred during hydrolytic degradation and rapid crystallization was observed for oligomer‐containing P(DLLA‐GA)(50/50) 20.…”

Section: Introductionmentioning

confidence: 99%

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Hydrolytic Degradation of Amorphous Films of L‐Lactide Copolymers with Glycolide and D‐Lactide

Saha

Tsuji

2006

Macro Materials & Eng

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Summary: Films of poly(L‐lactic acid) (PLLA) and copolymers of L‐lactide (LLA) with either glycolide [P(LLA‐GA)](81/19) or D‐lactide [P(LLA‐DLA)](77/23) were prepared and an effect of comonomer type on the hydrolytic degradation of the films was studied in phosphate‐buffered solutions at 37 °C. The degraded films were investigated using gravimetry (weight loss and water absorption), gel permeation chromatography, DSC, X‐ray diffractometry, tensile testing and polarization optical microscopy. To exclude the effects of molecular weight and crystallinity on hydrolytic degradation, the films were prepared from polymers with similar molecular weights and were made amorphous by melt quenching. It was found that the hydrolytic degradation rate decreased in the order P(LLA‐GA) > P(LLA‐DLA) > PLLA. The hydrolytic degradation rate constant of PLLA and LLA copolymer films increased with increasing the water absorption (hydrophilicity), or with decreasing the initial glass transition temperature or the L‐lactyl unit sequence length, indicating that the hydrolytic degradation rate of the copolymers was closely related to these three parameters. The crystallization of P(LLA‐GA) film occurred within hydrolytic degradation for 20 weeks.Mn of PLLA and LLA copolymer films as a function of hydrolytic degradation time.magnified imageMn of PLLA and LLA copolymer films as a function of hydrolytic degradation time.

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Section: Resultsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Hydrolytic Degradation of Amorphous Films of L‐Lactide Copolymers with Glycolide and D‐Lactide

Saha

Tsuji

2006

Macro Materials & Eng

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“…40 They are formed out of prevoids that are present in the polymer material. The total swelling of the polymer depends on the swelling of the polymer coils 41 and the forming of voids. 40 When the chain parts become so small that the polymer material starts to lose mass, the structure of the polymer device becomes very porous and the medium penetrates the porous structure and penetrates into the polymer.…”

Section: General Considerationsmentioning

confidence: 99%

“…They are formed out of prevoids that are present in the polymer material. The total swelling of the polymer depends on the swelling of the polymer coils and the forming of voids …”

Section: General Considerationsmentioning

confidence: 99%

Improved Mathematical Model for the Hydrolytic Degradation of Aliphatic Polyesters

et al. 2009

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The objective of this study was to develop a mathematical model that describes and even predicts the hydrolytic degradation of aliphatic polyesters. From literature, it is known that the main process of degradation of aliphatic polyesters is the autocatalytic hydrolysis of ester bonds. Because of this hydrolysis, polymer chains are cleaved and the molecular weight will decrease. With time, the molecules become small enough for the system to start losing weight, since the small molecules dissolve in the aqueous medium. In addition, the crystallinity can change during degradation and influence the degradation rate of the polymer and the monomer ratio of a copolymer. In order to test the model several aliphatic polyesters were synthesized. The degradation behavior of these polymers was investigated by placing them in an aqueous environment (pH ) 7.4) at 37 °C. At certain time intervals, samples of the polymers were taken and analyzed. A mathematical model was developed based on the autocatalytic hydrolytic degradation mechanism of aliphatic polyesters and verified with the measured results. Up to now, no models are known that include the autocatalytic hydrolysis behavior of aliphatic polyesters. The calculations of the new developed model are compared with measured results. It shows that it describes the concentration change of all polymer chains present as function of the degradation time. Hence, the change in molecular weight distribution, the decrease of the average molecular weight and the mass loss of the polymer as function of the degradation time can be predicted. This is a major advancement with respect to any earlier developed model. The only unknown input parameter for the model is the hydrolysis rate constant. The mathematical model is valid for semicrystalline as well as amorphous polymers and for copolymers.

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“…In particular, the intimate incorporation of different polymer ingredients at a hyperfine structural level will lead to not only the improvement of general material properties but also the desired control of the susceptibility to biodegradation. Such multicomponent biodegradable polymers may be grouped into three classes, namely, miscible or partially miscible blends, − block copolymers, − and graft copolymers. − The third class is mainly based on polysaccharides and would be anticipated to give rise to a diversity of degradation phenomena according to the degree of graft substitution onto the carbohydrate backbone and the total composition, in addition to the chemical sorts of selected polymeric constituents.…”

Section: Introductionmentioning

confidence: 99%

Biodegradable Cellulose Diacetate-graft-poly(l-lactide)s: Enzymatic Hydrolysis Behavior and Surface Morphological Characterization

Teramoto

Nishio

2003

Biomacromolecules

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Enzymatic hydrolysis of selected copolymers of cellulose diacetate-graft-poly(L-lactide)s (CDA-g-PLLAs) were conducted with proteinase K for film specimens, which were solely quenched from the molten state or, further, annealed at temperatures below or above their glass transition temperatures. The hydrolysis rates depended seriously on the thermal history, as well as on the graft modification. Especially, the heat treatment, followed by physical aging or crystallization of the originally amorphous materials, was a key factor to control subtly their enzymatic degradation behavior. Atomic force microscopy revealed that the enzymatic hydrolysis transformed the surface of the respective films into a more undulated one with a number of fine protuberances, for example, of several hundred nanometers in height and a few micrometers in width. Attenuated total reflection FTIR spectroscopy ensured selective release of lactyl units from the surface region. In visual appearance, some degraded films exhibited even an iridescent color due to an effect of interference of visible light reflected on the surface. These observations suggest a conception of "spatiotemporally controlled degradation", leading to a new method not only for regulation of the overall rate of degradation but also for fine surface abrasion of polymer materials.

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Effect of hydrolytic degradation and dehydration on the microstructure of 50:50 poly(glycolide-co-D,L-lactide)

Cited by 3 publications

References 4 publications

Hydrolytic Degradation of Amorphous Films of L‐Lactide Copolymers with Glycolide and D‐Lactide

Hydrolytic Degradation of Amorphous Films of L‐Lactide Copolymers with Glycolide and D‐Lactide

Improved Mathematical Model for the Hydrolytic Degradation of Aliphatic Polyesters

Biodegradable Cellulose Diacetate-graft-poly(l-lactide)s: Enzymatic Hydrolysis Behavior and Surface Morphological Characterization

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