Polymerizable Oxygen Probe Derived from Platinum-Based Porphyrins for Oxygen Sensing and Pressure-Sensitive Paints

Abstract

In this work, a polymerizable oxygen probe (PtTFPP-1MA) derived from platinum(II)- 5,10,15,20-tetrakis-(2,3,4,5,6-pentafluorophenyl)-porphyrin (PtTFPP) was synthesized and characterized. The probe PtTFPP-1MA with a methacrylate unit can be copolymerized with other monomers; herein, we used t-butyl styrene (tBs) as a representative monomer for the oxygen sensor and pressure-sensitive paint (PSP). Three copolymers of poly(tBs-co-(PtTFPP-1MA)) (P1a−c) with different PtTFPP-1MA contents were synthesized. Results showed that the oxygen-sensing ability of these polymers exhibited similar oxygen sensitivity, indicating that the compositions of the probe concentrations in our chosen ranges did not have significant influences on sensing. To determine the properties' difference of probe between the physical doping approach with the chemical copolymerization method in the polymer matrix, poly(tBs) (P2) without PtTFPP-1MA were prepared. Results showed that the polymers (P1a−c) prepared by the chemical copolymerization method exhibited better performance in oxygen-and pressuresensing tests. In order to investigate whether steric hindrance of the bulky t-butyl group has a significant effect on sensing, poly(St-co-(PtTFPP-1MA)) (P3) using polystyrene with the t-butyl moiety as the matrix was synthesized for comparison. Results confirmed that P1a with the bulky t-butyl group possesses much better sensing performance than P3. P1a's pressure sensitivity (0.75%/kPa) at 20 °C is among the highest values in reported PSPs, and its temperature sensitivity (−0.63%/°C) at 100 kPa is among the lowest in reported PSPs. It is expected that the polymerizable oxygen probe PtTFPP-1MA could be widely used in oxygen sensors and PSPs.

Synthesis of fluorinated copolymers and their applications as pressure‐responsive materials

“…PtTFPP‐1MA was synthesized according to the procedure we reported earlier 33 . t‐Butyl styrene (tBs) and TFEM were obtained from Aladdin (Beijing, China) and passed through basic aluminum oxide column to remove stabilizers.…”

“…PtTFPP-1MA was synthesized according to the procedure we reported earlier. 33 t-Butyl styrene (tBs) and TFEM were obtained from Aladdin (Beijing, China) and passed through basic aluminum oxide column to remove stabilizers. Azodiisobutyronitrile (AIBN) was commercially available from Sigma-Aldrich (Saint Louis, America) and recrystallized from ethanol for purification before use.…”

“…Where P 0 was synthesized as we reported previously. 33 A certain amount of tBs, TFEM, PtTFPP-1MA and 8.0 mg of AIBN were dissolved in 3 mL of trifluorotoluene in a 10 mL Schlenk tube and the feed ratios were shown in Table 1. Oxygen in the mixed solutions were removed through 3 cycles of free-zeÀpumpÀthaw.…”

“…32 In our previous work, a polymerizable oxygen probe PtTFPP-1MA (its structure was given in Scheme 1) that derived from platinum(II)-5,-10,15,20-tetrakis-(2,3,4,5,6-pentafluorophenyl)-porphyrin (PtTFPP) was copolymerized with t-butyl styrene (tBS) to obtain a series of copolymers with excellent performance. 33 These PSPs prepared by chemical copolymerization showed better performance in oxygen and pressure tests than those prepared by physical doping. Because the tert-butyl group has relatively large spatial volume, these materials exhibit both good pressure sensitivity (0.75%/ kPa) at 20 C (being among the highest of reported PSPs) and low temperature influence(À0.63%/ C) at 100 kPa (being among the lowest of reported PSPs).…”

“…In addition, the key to achieve excellent pressure sensitivity performance of the PSPs is to improve the oxygen sensitivity of the oxygen probes and the oxygen permeability of the polymer matrices 32 . In our previous work, a polymerizable oxygen probe PtTFPP‐1MA (its structure was given in Scheme 1) that derived from platinum(II)‐5,10,15,20‐tetrakis‐(2,3,4,5,6‐pentafluorophenyl)‐porphyrin (PtTFPP) was copolymerized with t‐butyl styrene (tBS) to obtain a series of copolymers with excellent performance 33 . These PSPs prepared by chemical copolymerization showed better performance in oxygen and pressure tests than those prepared by physical doping.…”