Characterization of siloxane residues from polydimethylsiloxane elastomers by MALDI-TOF-MS

Hunt, Simon A.; George, Graeme A.

doi:10.1002/1097-0126(200007)49:7<633::aid-pi528>3.0.co;2-r

Cited by 16 publications

(7 citation statements)

References 9 publications

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“…The heptane extracts were collected in glass vials. After evaporation of the heptane, the residue was dissolved in 1 mL chloroform 11. HABA and DHB, both at a concentration of 10 g/L in THF, were used for MALDI sample preparation.…”

Section: Methodsmentioning

confidence: 99%

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Degradation of biomedical polydimethylsiloxanes during exposure to in vivo biofilm environment monitored by FE‐SEM, ATR‐FTIR, and MALDI‐TOF MS

Kaali

Momcilovic

Markström

et al. 2009

J of Applied Polymer Sci

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Polymers used for biomedical purposes in medical devices are usually requested to be inert to degradation. This article describes that slow irreversible changes were observed in silicone surfaces exposed to in vivo biofilms even if silicone, in general, is supposed to have excellent long-term properties. Tracheostomy tubes made of silicone rubber were exposed to in vivo biofilm environments in clinical tests for periods of 1, 3, and 6 months. The chemical degradation was monitored by MALDI-TOF MS, ATR-FTIR, and FE-SEM. In addition, the physical changes were monitored by contact angle and hardness measurements. Cyclic polydimethylsiloxane (PDMS) was detected on the surfaces of new (unaged) silicones. On the surfaces of the in vivo samples new compounds, presumably linear methyl-hydroxyl-terminated PDMS, were detected in addition to cyclic PDMS. These compounds may be formed as a result of the hydrolysis of linear dimethyl terminated PDMS, which is also present in the silicone rubber. ATR-FTIR spectroscopy confirmed that hydrolysis had indeed occurred during the in vivo exposure, since SiAOH groups were detected. Furthermore, significant changes in the topography were detected by FE-SEM, indicating the initiation of degradation. No significant changes in the contact angle of the in vivo used samples were observed, but this information may be shielded by the fact that biofilm may remain on the surface, despite the thorough cleaning before the analysis. It is also possible that the surface hydrophobicity was recovered by the diffusion of linear low-molecular-weight compounds from the bulk.

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Section: Methodsmentioning

confidence: 99%

“…Chain scission results in loss of hydrophobicity (since hydrophilic groups are formed) and the migrating LMW compounds are responsible for the hydrophobic recovery of the surface 6–10. These LMW compounds were found to be linear PDMS with methyl and/or hydroxyl end groups 11, 12…”

Section: Introductionmentioning

confidence: 99%

Degradation of biomedical polydimethylsiloxanes during exposure to in vivo biofilm environment monitored by FE‐SEM, ATR‐FTIR, and MALDI‐TOF MS

Kaali

Momcilovic

Markström

et al. 2009

J of Applied Polymer Sci

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“…The result indicates that N-3 has many more methyl end-groups. Referring to the data on soft ionization published in the literature [ 20 ], we propose that peak N-3 is a linear LMW siloxane, and peak N-11 is a cyclic LMW siloxane. Thus, the peak N-11 represents the substance of D

, while N-3 represents the substance of L

=CH

[(CH

)

SiO]

Si(CH

)

).…”

Section: Results and Discussionmentioning

confidence: 81%

New Aspects of Degradation in Silicone Rubber under UVA and UVB Irradiation: A Gas Chromatography–Mass Spectrometry Study

et al. 2021

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In this paper, gas chromatography–mass spectrometry (GC–MS) and positron annihilation lifetime spectroscopy (PALS) were used to probe the changes of oligomers and the polydimethylsiloxane (PDMS) network in silicone rubber, after different durations of UVA/UVB irradiation. At the early stage (<300 h) of UVA/UVB irradiation, the concentration of D4-D9 decreases. The o-Ps intensity of the extracted silicone rubber increases in the stage after UVB irradiation. These results indicate the crosslinking of oligomers into the PDMS network. After a long duration (>300 h) of UVB irradiation, D4 was generated and the lifetime of τ3 also increased, indicating the rupture of the Si-O bond in the PDMS network. These two aging processes were termed the post curing process and the chain session process. The new finding was that UVA could only induce the post curing process; UVB causes the rupture of the chemical bond in silicone rubber. Photons of UVB could break the C-H bond, and then trigger the backbiting decomposition of PDMS, breaking the Si-O bond, while the photons of UVA cannot. The fact that D4 was generated after UVB irradiation can be used to evaluate the UVB stability of silicone rubber in the future.

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“…Figure shows the total ion chromatogram of the n ‐hexane extracts for the 0 wt % ATH sample in GC–MS. General formulae for LMW oligomers are D n = [(CH 3 ) 2 SiO] n (cyclic siloxanes) and L n = CH 3 [(CH 3 ) 2 SiO] n Si(CH 3 ) 3 (linear siloxanes) . The first peak appearing at 6.90 min turns out to be D 4 by comparing with the NIST08 data base.…”

Section: Resultsmentioning

confidence: 99%

“…Peaks appearing at 8.70, 10.39, 11.88, 13.20, 14.32, 15.32, 16.23, 17.06, 17.82, 18.53, 19.20, 19.95, 20.82, 21.87, 23.17, and 24.83 min have been assigned to cyclic dimethylsiloxane oligomers (from D5 to D20, respectively) by GC–MS. Other peaks appearing at 16.56, 17.38, 18.14, 18.84, 19.56, 20.33, 21.42, and 22.73 min, respectively, are linear siloxanes . Because of the greater compactness of cyclic LMW siloxanes, their ability to diffuse in the PDMS network is 20% faster than the corresponding linear species .…”

Section: Resultsmentioning

confidence: 99%

Effect of aluminum hydroxide on low‐molecular‐weight siloxane distribution and microstructure of high‐temperature vulcanized silicone rubber

Wang

Yin

Luo

et al. 2017

J of Applied Polymer Sci

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This paper investigates the effect of aluminum hydroxide (ATH) content on the free volume and surface recovery property of polydimethylsiloxane (PDMS)-based silicone rubber containing low-molecular-weight siloxanes. With increasing ratio of ATH up to 43.1 wt %, the concentration of cyclic siloxanes (D n 5 [(CH 3 ) 2 SiO] n , n 5 4-12) in the PDMS matrix increases remarkably, indicative of a spacing effect of ATH particles on the crosslinking of PDMS chains. When more ATH is added, the concentration of D 4 -D 12 began to decrease. PDMS network variation is verified by free volume size corresponding to s 3 in positron annihilation lifetime spectroscopy. The o-Ps intensity decreases linearly with ATH content. Data obtained from X-ray photoelectron spectroscopy suggest the surface recovery property is weakened by ATH. This process is dominated by the amount of free volume holes in the sample. V C 2017Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45803.

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Characterization of siloxane residues from polydimethylsiloxane elastomers by MALDI-TOF-MS

Cited by 16 publications

References 9 publications

Degradation of biomedical polydimethylsiloxanes during exposure to in vivo biofilm environment monitored by FE‐SEM, ATR‐FTIR, and MALDI‐TOF MS

Degradation of biomedical polydimethylsiloxanes during exposure to in vivo biofilm environment monitored by FE‐SEM, ATR‐FTIR, and MALDI‐TOF MS

New Aspects of Degradation in Silicone Rubber under UVA and UVB Irradiation: A Gas Chromatography–Mass Spectrometry Study

Effect of aluminum hydroxide on low‐molecular‐weight siloxane distribution and microstructure of high‐temperature vulcanized silicone rubber

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