Thermal polydimethylsiloxane degradation. Part 2. The degradation mechanisms

Camino, Giovanni; Ломакин, С. М.; Lageard, M.

doi:10.1016/s0032-3861(01)00785-6

Cited by 479 publications

(358 citation statements)

References 9 publications

Supporting

Mentioning

337

Contrasting

Unclassified

Order By: Relevance

“…H vs. Y crosslinking via varying free radical mechanisms), bonding to the filler matrix, etc. [1][2][3][4][6][7][8][9][10][11][12][13][14][15] For both thermally and radiation induced degradation multiple, competing reaction pathways can exist and occur simultaneously to varying extent dependent on variables such as total input energy, monomer types (i.e. stabilizing phenyl groups), additives (fillers, stabilizers, etc.…”

Section: Spectrometry (Gc/ms) the Mechanical Data Andmentioning

confidence: 99%

MQ NMR and SPME Analysis of Nonlinearity in the Degradation of a Filled Silicone Elastomer

et al. 2010

View full text Add to dashboard Cite

Radiation-induced degradation of polymeric materials occurs through numerous, simultaneous, competing chemical reactions. Although degradation is typically found to be linear in adsorbed dose, some silicone materials exhibit nonlinear dose dependence due to dose-dependent dominant degradation pathways. We have characterized the effects of radiative and thermal degradation on a model filled-PDMS system, Sylgard 184 (commonly used in electronic encapsulation and in biomedical applications), using traditional mechanical testing, NMR spectroscopy, and sample headspace analysis using solid-phase microextraction (SPME) followed by gas chromatography/mass spectrometry (GC/MS). The mechanical data and 1H spin−echo NMR spectra indicated that radiation exposure leads to predominantly cross-linking over the cumulative dose range studied (0−250 kGy) with a rate roughly linear with dose. 1H multiple-quantum NMR spectroscopy detected a bimodal distribution in the network structure, as expected from the proposed structure of Sylgard 184. The MQ NMR spectra further indicated that the radiation-induced structural changes were not linear in adsorbed dose and that competing chain scission mechanisms made a greater contribution to the overall degradation process in the range of 50−100 kGy (although cross-linking still dominated). The SPME−GC/MS data were analyzed using principal component analysis (PCA), which identified subtle changes in the distributions of degradation products (the cyclic siloxanes and other components of the material) as a function of age that provide insight into the dominant degradation pathways at low and high adsorbed dose.

show abstract

Section: Spectrometry (Gc/ms) the Mechanical Data Andmentioning

confidence: 99%

MQ NMR and SPME Analysis of Nonlinearity in the Degradation of a Filled Silicone Elastomer

et al. 2010

View full text Add to dashboard Cite

show abstract

“…The incorporation of aromatic structures into the polymer chain backbone increases both the threshold temperature for the degradation and the temperature at which the maximum rate of volatile emissions occur. Camino et al (2002) report that earlier work shows that the thermal degradation of PDMS end-blocked with (CH 3 )Si-groups in inert atmospheres (e.g. N 2 ) and under vacuum results in depolymerisation and the formation of cyclic oligomers.…”

Section: Breakdown Of Pdms Polymersmentioning

confidence: 83%

“…Overall, Camino et al (2002) conclude that thermal degradation of PDMS occurs through two competing mechanisms. The first is a molecular mechanism that forms cyclic oligomers.…”

mentioning

confidence: 79%

“…It is also reported that cationic reactions on glass surfaces can contribute to the thermal degradation of PDMS polymers. Camino et al (2002) carried out further experiments to investigate the mechanism of thermal degradation of PDMS [end-blocked with (CH 3 )Si-groups and containing a vinylmethylsiloxane unit every 1400th -(CH 3 ) 2 -Si-O-unit, with a viscosity of 8 × 10 6 mPa 9 ). Experiments were carried out in either a helium or air atmosphere in a glass container, and two types of heating regime were used.…”

Section: Breakdown Of Pdms Polymersmentioning

confidence: 99%

See 1 more Smart Citation

Temperature Dependence of the Organic Carbon/Water Partition Ratios (K_OC) of Volatile Methylsiloxanes

Panagopoulos

Jahnke

Kierkegaard

et al. 2017

Environ. Sci. Technol. Lett.

View full text Add to dashboard Cite

Knowing the temperature dependence of the organic carbon/water partition ratios (K OC ) of volatile methylsiloxanes (VMS) is required to understand their environmental fate. We measured the K OC of two linear VMS (lVMS), three cyclic VMS (cVMS), and six polychlorinated biphenyls (PCBs) at 25, 15, 10, and 5 °C and calculated their enthalpies and entropies of sorption to organic carbon (ΔH OC and ΔS OC , respectively). The ΔH OC of VMS ranged from −79.2 to −45.8 kJ mol −1 , while the ΔH OC of the PCBs ranged from −68.7 to −29.3 kJ mol −1 . Previously reported measurements of the enthalpy of phase change between octanol and water (ΔH OW ) for cVMS (11.3−68.8 kJ mol −1 ) differed substantially from our ΔH OC measurements, even showing different signs (negative versus positive). Literature data of ΔH OC and ΔH OW for PCBs (−61 to −17 kJ mol −1 ) are closer to our measured values of ΔH OC for the PCBs showing the same sign (negative) with differences within a factor of 2 in the majority of the cases. Comparison of all available data for PCBs and VMS indicated that there may be important differences between ΔH OC and ΔH OW , especially for the VMS. Therefore, assuming ΔH OC equals ΔH OW in environmental fate models may be a source of substantial error.

show abstract

“…The weight loss from 450 °C up to 630 °C (30 wt. %) may be attributed to elimination of methyl groups in PDMS [35,36]. On the other hand, materials with more than 15 % of OPU suffer a weight loss greater than 30%.…”

Section: Modulation Of the Hydrophilic Character And Influence On Thementioning

confidence: 99%

Modulación del carácter hidrofílico e influencia sobre la biocompatibilidad de híbridos base poliuretano-siloxano

Jiménez-Gallegos¹,

Téllez-Jurado²,

Rodríguez‐Lorenzo³

et al. 2011

Bol. Soc. Esp. Ceram. Vidr.

View full text Add to dashboard Cite

Organic-inorganic hybrid materials are known for their outstanding chemical and physical properties. Although some studies have been published regarding the use of hybrids for biomedical applications, relationship between hydrophilic character and biodegradation, bioactivity and biocompatibility has not been studied yet. The sol-gel method has been chosen for the manufacturing of siloxane-polyurethane hybrids for the exceptional potential of the method to obtain nanostructured materials. The effect of the amount of the urethane oligomer (OPU) on the structure, hydrophilic character, degradability, bioactivity and citotoxicity was investigated. Gelling time of these hybrids increases linearly with the decrease on the Siloxane/OPU ratio up to an 80/20 value. Hydrophilic character of the hybrids can be modulated and affects dramatically the degradation rate of the specimens. A hybrid with a 50/50 Siloxane/OPU ratio displayed an appropriate degradation rate, bioactivity and lack of cell toxicity that makes this material a candidate for further studies for applications in bone regeneration.Keywords: Sol-gel process; Biomedical applications; Hybrid Materials; Bioactivity; Polyurethane. Modulación del carácter hidrofílico e influencia sobre la biocompatibilidad de híbridos base poliuretano-siloxanoLos materiales híbridos Orgánico-Inorgánico son conocidos por sus excepcionales propiedades químicas y físicas. Aunque se han publicado algunos estudios respecto al uso de híbridos para aplicaciones biomédicas, aun faltan estudios que determinen la relación que existe entre el carácter hidrofílico de estos materiales y las propiedades que les permiten ser utilizados como biomateriales: degradación, bioactividad y biocompatibilidad. El método sol-gel se ha escogido para la fabricación de híbridos debido a la posibilidad de obtener materiales nanoestructurados que comprenden un componente orgánico y un inorgánico. Se investigó el efecto de la cantidad del olígomero de uretano (OPU) sobre la estructura, el carácter hidrofílico, la degradabilidad, la bioactividad y la citotoxicidad. El tiempo de gelificación de estos híbridos incrementa linealmente con la disminución en la relación Siloxano/OPU hasta un valor de 80/20. El carácter hidrofílico de los híbridos se puede modular y afectar considerablemente la velocidad de degradación de las muestras. Un híbrido con una relación 50/50 Siloxane/OPU muestra una velocidad de degradación, una bioactividad y falta de toxicidad que hacen a este material un candidato para futuros estudios para aplicaciones en regeneración ósea.

show abstract

Thermal polydimethylsiloxane degradation. Part 2. The degradation mechanisms

Cited by 479 publications

References 9 publications

MQ NMR and SPME Analysis of Nonlinearity in the Degradation of a Filled Silicone Elastomer

MQ NMR and SPME Analysis of Nonlinearity in the Degradation of a Filled Silicone Elastomer

Temperature Dependence of the Organic Carbon/Water Partition Ratios (K_OC) of Volatile Methylsiloxanes

Modulación del carácter hidrofílico e influencia sobre la biocompatibilidad de híbridos base poliuretano-siloxano

Contact Info

Product

Resources

About

Thermal polydimethylsiloxane degradation. Part 2. The degradation mechanisms

Cited by 479 publications

References 9 publications

MQ NMR and SPME Analysis of Nonlinearity in the Degradation of a Filled Silicone Elastomer

MQ NMR and SPME Analysis of Nonlinearity in the Degradation of a Filled Silicone Elastomer

Temperature Dependence of the Organic Carbon/Water Partition Ratios (KOC) of Volatile Methylsiloxanes

Modulación del carácter hidrofílico e influencia sobre la biocompatibilidad de híbridos base poliuretano-siloxano

Contact Info

Product

Resources

About

Temperature Dependence of the Organic Carbon/Water Partition Ratios (K_OC) of Volatile Methylsiloxanes