Direct mass spectrometry of polymers. VII. Primary thermal fragmentation processes in polycarbonates

Foti, Salvatore; Giuffrida, Mario; Maravigna, P.; Montaudo, Giorgio

doi:10.1002/pol.1983.170210602

Cited by 48 publications

(31 citation statements)

References 13 publications

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“…The persistence of peaks due to cyclic oligomers in the MALDI spectra can be justified by assuming the presence of an equilibrium between the rate of cleavage and the rate of formation of cycles (Scheme 1a). This result is in agreement with the data illustrated in our previous DPMS studies on PC degradation, 5,6 in which it has been shown that cyclic oligomers are generated by an intramolecular exchange reaction (Scheme 1a), in the initial stages of the thermal degradation (300-350°C).…”

Section: Resultssupporting

confidence: 94%

“…In the spectrum obtained after heating 15 min, is present a strong peak at m/z 2775 (marked as G in Figure 5), which is located 18 mass units lower than peak D, and it can be assigned to PC oligomers terminated with phenol groups at both ends and containing one xanthone unit along the chain (species G, Table 2). The formation of pyrolysis compounds containing xanthone units during the thermal degradation of PC has been also detected in the previous DPMS study, 5 and it is thought to occur by a thermal rearrangement (Scheme 1e) taking place in parallel to other pyrolysis processes.…”

Section: Resultsmentioning

confidence: 84%

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MALDI−TOF Investigation of Polymer Degradation. Pyrolysis of Poly(bisphenol A carbonate)

Puglisi¹,

Samperi²,

Carroccio³

et al. 1999

Macromolecules

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The MALDI-TOF technique allows the detection of intact polymer molecules up to high masses and therefore offers the opportunity to study directly the thermal degradation processes occurring in polymeric materials by analyzing conveniently exposed (i.e., partially degraded) polymer samples. This opens new vistas in polymer analysis and deserves careful exploration, due to the relevance of polymer degradation phenomena in everyday practice.The thermal decomposition of poly(bisphenol A carbonate) (PC) has been investigated by heating isothermally at 300, 350, 400, and 450°C and subsequent analysis of the pyrolysis residue by means of MALDI mass spectrometry. The MALDI mass spectra of the pyrolysis residues obtained at 300°C showed a progressive reduction of the abundance of cyclic oligomers, whereas the relative abundance of the other compounds was unaffected. At 350°C, the occurrence of an extensive hydrolysis reaction was responsible for the degradation of cycles and linear chains bearing tert-butylphenyl carbonate end groups with subsequent formation of abundant open chain PC oligomers with phenol end groups. Furthermore, at these two temperatures, cyclic oligomers never disappear in the MALDI spectra, even at higher heating time (60 min), suggesting the presence of an equilibrium between the rate of cleavage and the rate of formation of cycles. PC chains terminated with phenol groups at both ends, together with pyrolyzed chains bearing phenyl and isopropylidene end groups, generated by the disproportionation of the aliphatic bridge of bisphenol A, were observed in the MALDI spectra of pyrolysis residue obtained at 400°C. Condensed aromatic compounds such as xanthones, which are considered to be the precursors of a graphite-like structure of the charred residue, were also detected in the MALDI spectra of PC samples heated at 400°C and they became the most intense species at 450°C. The PC samples heated at temperature higher than 450°C consisted of insoluble carbonaceous materials not suitable for MALDI analysis.

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Section: Resultssupporting

confidence: 94%

Section: Resultsmentioning

confidence: 84%

MALDI−TOF Investigation of Polymer Degradation. Pyrolysis of Poly(bisphenol A carbonate)

Puglisi¹,

Samperi²,

Carroccio³

et al. 1999

Macromolecules

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“…Cyclic carbonates, once formed, are thermally degraded, undergoing hydrolysis and decarboxylation. 69 It has been a fR-O-co-oi…”

Section: Polycarbonatesmentioning

confidence: 99%

“…[60][61][62][63][64][65][66][67][68][69][70] As in the case of polyesters, aliphatic and aliphatic-aromatic polycarbonates easily undergo secondary thermal decomposition reactions, and cyclic carbonates are therefore accompanied by products originating from J3-CH hydrogen transfer processes. 69,[72][73][74] In the case of polycarbonates the thermal stability is also a function of the conformational flexibility of the structural units in the polymer. 69…”

Section: Rfr-o-co-ol]mentioning

confidence: 99%

Thermal Degradation Mechanisms in Condensation Polymers

Montaudo

Puglisi

1987

Developments in Polymer Degradation—7

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“…As an example, aromatic polycarbonates are used on large scale for the production of CDs. The thermal properties of several aliphatic and aromatic polyi.exe carbonates [8][9][10][11][12][13][14][15][16][17] have been studied using various techniques such as differential scanning calorimetry (DSC), powder X-ray analyses at various temperatures and thermogravimetrical analyses (TGA). The main purpose of this paper is to study the thermal degradation route of some new polycarbonates with the main objective of understanding how the thermal degradation temperature can be controlled by tailoring the chemical structure of the polymer backbone.…”

Section: Introductionmentioning

confidence: 99%

Thermodegradable polycarbonates: Effect of substituents on the degradation temperature

et al. 2002

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Abstract:The thermal degradation process of some new polycarbonates is investigated from an experimental and theoretical point of view, in order to obtain insight into the microscopic aspects that influence the reaction mechanism and the process of thermolysis. In particular, attention is focussed on the influence of the type of substituents in the polymer chain on the degradation temperature. A series of novel polycarbonates were designed differing from each other by the groups attached at the α and β carbon atoms. Thermal behavior was characterized by thermogravimetrical analyses. The polymers undergo rapid and complete thermolysis at different degradation temperatures depending on the structure. The degradation products were separated by gas chromatography and analyzed by mass spectroscopy. The ratio of formed dienes in the product distribution depends on the heating rate. Furthermore, density functional theory calculations were performed on a series of model compound systems for the polycarbonates under study, in particular carbonate systems differing by the groups attached at the α and β carbons. The study proves that the thermal degradation route can be controlled by tailoring the polymer backbone structure. Moreover, ab initio calculations provide further insight into the microscopic ingredients that govern the degradation process and associated reaction rates.

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Direct mass spectrometry of polymers. VII. Primary thermal fragmentation processes in polycarbonates

Cited by 48 publications

References 13 publications

MALDI−TOF Investigation of Polymer Degradation. Pyrolysis of Poly(bisphenol A carbonate)

MALDI−TOF Investigation of Polymer Degradation. Pyrolysis of Poly(bisphenol A carbonate)

Thermal Degradation Mechanisms in Condensation Polymers

Thermodegradable polycarbonates: Effect of substituents on the degradation temperature

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