Synthesis and characterization of phosphonate and aromatic‐based polynorbornene polymers derived from the ring opening metathesis polymerization method and investigation of their thermal properties

Abstract

In the present study, phosphonate ester, phosphonic acid, and aromatic (phenyl, naphthalene, anthracene) groups containing polymers were synthesized by the ROMP method to analyze thermal properties of these polymers. Thermal stability of the synthesized polymers is tested by thermal gravimetric analysis under nitrogen, air, and microscale combustion calorimetry analysis. Analysis shows that thermal behavior is directly related to the phosphorus level in the copolymer series. All the polymers are thermally stable under nitrogen and air up to 900 °C. Synergistic charring effect under air was observed between aromatic groups and phosphonic acid functionality in the copolymer series. Anthracene units have a greater potential to form carbonaceous char than the naphthalene and phenyl units. Phosphonate ester and naphthalene units bearing copolymers (P3A) gave 8.13% char yield at 900 °C under air. Phosphonic acid derivatives of this polymer, P3D, gave a highest char residue of 17.15% under the same condition. The introduction of phosphonate and phosphonic acid in each copolymer series is also beneficial in reducing the peak heat release rate (PHRR). Cleavage of the phosphonate ester bearing homopolymer (P4) to phosphonic acid (P4A) causes a sharp decrease in the PHRR ratio from 274 to 28.2 W/g. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47085.

Synthesis and Characterization of Polyphosphonates and Polyurethanes Using Chalcone and DOPO-Chalcone as a Flame Retardant

“…Most of the polymer series was stable in the temperature range from 25 to 300 °C. The weight loss in this range is due to the loss of the residual solvent and dehydration of residual water . The −O–P­(O)–O bond in the structure was broken at around 250–350 °C.…”

“…Further, we performed MCC analysis on the series of polyphosphonates. MCC is used to evaluate the flammability behavior of samples using a milligram scale . Approximately 5 mg of the sample was heated up to 750 °C at a heating rate of 1 K/s under an inert atmosphere until it was completely pyrolyzed, and the heat release capacities of the samples were analyzed.…”

“…HRC and HRR are important parameters for evaluating the flame retardancy of products. If the product possesses thermal stability, in other words, low flammability, the HRR value will be lower. , Table shows that the DOPO–chalcone polyphosphonates have much higher HRC and HRR values when compared to the chalcone-based polyphosphonates. The HRC results for (DHC–PPDC) 80 , (DHC–PPDC) 0 , and (DHC–PPDC) 25 are 54, 77, and 88 J/g K, respectively.…”

“…67 Thus, cleavage of DOPO from DHC−DOPO−PU produced pyrophosphate and derivatives at a comparatively lower temperature under an air atmosphere. 3,47,67 On the other hand, the char formation was higher for the DHC−PU-type polyurethane than for DHC− DOPO−PU under a N 2 atmosphere. Basically, DOPO is cleaved from the polyurethane matrix and purged away via N 2 gas flow, like in the polyphosphonate series discussed earlier, and the formation of graphite-like char residues is more dominant with the chalcone internal double bonds.…”

“…The weight loss in this range is due to the loss of the residual solvent and dehydration of residual water. 47 The −O−P(O)−O bond in the structure was broken at around 250−350 °C. The third degradation stage above 400 °C was attributed to the thermal degradation of the polymers and splitting of chains and release of gaseous products.…”