Does the oxa-Michael reaction of 2-trifluoromethacrylic acid lead to fluorinated polyesters?

• Published in: Polymer chemistry Vol. 12; no. 31; pp. 458 - 4523
• Main Authors: Tran-Do, Minh-Loan, Eid, Nadim, Totée, Cédric, Gimello, Olinda, Améduri, Bruno
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 21.08.2021
• Subjects: Acids; Addition polymerization; Aluminum chloride; Amines; Contact angle; Degree of polymerization; Differential scanning calorimetry; Fluorination; Glass transition temperature; Initiation (polymerization); Michael reaction; NMR spectroscopy; Oligomers; Peroxides; Phosphines; Piperidine; Polyester resins; Polyesters; Polymer chemistry; Thermodynamic properties; Thermogravimetric analysis; Triflic acid
• ISSN: 1759-9954; 1759-9962
• DOI: 10.1039/d1py00685a

2-Trifluoromethacrylic acid (MAF) is a peculiar fluorinated functional monomer. Though it is known to polymerise via C&z.dbd;C bond cleavage under anionic initiation, its oxa-Michael addition polymerisation afforded polyesters bearing trifluoromethyl side groups. This oxa-Michael addition was attempted in the presence of radical (peroxides), basic (amines and phosphines) and acidic (AlCl 3 , triflic acid, and p -toluenesulfonic acid) reactants and catalysts which led to the formation of oligomers with various yields (up to 57%) and molar masses (up to 2200 g mol −1 ). The obtained polyesters were characterised by GC/MS, IR, 19 F NMR, 1 H NMR and 13 C NMR spectroscopy techniques and MALDI-TOF, and their thermal properties were determined by thermogravimetric analysis and differential scanning calorimetry. Triphenylphosphine and piperidine led to the highest degree of polymerization DP n (up to the 16th adduct) with a degradation temperature of about 200 °C. The glass transition temperatures ( T g ) were −59 and −46 °C for the MAF bisadduct (diMAF) and oligoMAF, respectively. Such oligomers were hydrophobic, evidenced by a water contact angle measurement of 107°, showing that the contribution of the trifluoromethyl group was higher than that of the ester function. 2-Trifluoromethacrylic acid (MAF) is a peculiar fluorinated functional monomer.