Side chain piperidine cation grafting type polybiphenyl alkaline membrane and preparation method thereof

[0055] Example 1

[0056] The preparation of 1-(3-bromopropyl)-1-methylpiperidine cationic grafted polybiphenyl (PBP-3-Pip) alkaline membrane, such as figure 1 As shown, it is the preparation process of 1-(3-bromopropyl)-1-methylpiperidine cationic grafted polybiphenyl (PBP-3-Pip) alkaline membrane in Example 1 of the present invention, and the specific steps are as follows :

[0057] (1) Preparation of polybiphenyl (PBP)

[0058] Biphenyl (1 g) and N-methylpiperidone (0.83 mL) were dissolved in dichloromethane (5 mL); then, a mixed liquid of trifluoromethanesulfonic acid (5 mL) and trifluoroacetic acid (0.5 mL) was added gradually. dropwise, and reacted at 0 °C for 6 h to obtain a wine-red viscous liquid. 2 CO 3 Precipitate in aqueous solution, soak at room temperature for 24 hours, and filter to obtain a white solid sample, which is fully washed with deionized water and dried to obtain polybiphenylpiperidine (PBP) polymer;

[0059] (2) Preparation of 1-(3-bromopropyl)-1-methylpiperidine (Br-3-Pip)

[0060] 1,3-Dibromopropane (1.25 mL), N-methylpiperidine (1 mL), and ethyl acetate (20 mL) were added to a round-bottomed flask, and nitrogen was passed through to fully react to obtain a white solid precipitate, which was filtered with suction , purified with ethyl acetate, removed excess reactant, and dried to give side-chain piperidine cation 1-(3-bromopropyl)-1-methylpiperidine (Br-3-Pip);

[0061] (3) Preparation of 1-(3-bromopropyl)-1-methylpiperidine cationic grafted polybiphenyl (PBP-3-Pip) polymer

[0062] The PBP (1 g) prepared in step (1) was dissolved in dimethyl sulfoxide (DMSO) (50 mL), and after the polymer was completely dissolved, an excess of the side chain piperidine cation 1-( 3-Bromopropyl)-1-methylpiperidine (Br-3-Pip) was subjected to quaternization reaction; after 72 hours of reaction at 90°C, the solution was spin-dried to obtain the crude side chain piperidine cation grafted type Polybiphenyl solid; washed the crude product with ethyl acetate and deionized water to remove the remaining Br-3-Pip, suction filtered, and dried to obtain pure 1-(3-bromopropyl)-1-methyl Polypiperidine cationically grafted polybiphenyl (PBP-3-Pip) polymers; such as Pic 4-1 shown, is the general structure of the 1-(3-bromopropyl)-1-methylpiperidine cationic grafted polybiphenyl (PBP-3-Pip) polymer prepared in Example 1 of the present invention;

[0063] (4) Preparation of 1-(3-bromopropyl)-1-methylpiperidine cation-grafted polybiphenyl (PBP-3-Pip) alkaline membrane

[0064] The 1-(3-bromopropyl)-1-methylpiperidine cationic grafted polybiphenyl (PBP-3-Pip) polymer (1g) obtained in step (3) was dissolved in dimethyl sulfoxide (DMSO) (10mL), a certain concentration of casting solution was prepared, and then the casting solution was cast or cast on a heat-resistant glass plate, cured, and peeled off; finally, the obtained alkaline membrane was immersed in 2M NaOH In an aqueous solution, soaked for 48 hours to obtain the final 1-(3-bromopropyl)-1-methylpiperidine cation-grafted polybiphenyl (PBP-3-Pip) alkaline membrane in the form of hydroxide.

[0065] Example 2

[0066] The preparation of 1-(6-bromohexyl)-1-methylpiperidine cationic grafted polybiphenyl (PBP-6-Pip) alkaline membrane, such as Figure 4-2 As shown, it is the preparation flow chart of 1-(6-bromohexyl)-1-methylpiperidine cation-grafted polybiphenyl (PBP-6-Pip) alkaline membrane in Example 2 of the present invention; the specific preparation process as follows:

[0067] (1) Preparation of polybiphenyl (PBP)

[0068] With embodiment 1;

[0069] (2) Preparation of 1-(6-bromohexyl)-1-methylpiperidine (Br-6-Pip)

[0070] 1,6-Dibromohexane (1.5 mL), N-methylpiperidine (1 mL), and ethyl acetate (20 mL) were added to a round-bottomed flask, and nitrogen was passed through to react fully to obtain a white solid precipitate, which was evacuated. Filtration, purification with ethyl acetate, removal of excess reactant, and drying to give side chain piperidine cation 1-(6-bromohexyl)-1-methylpiperidine (Br-6-Pip);

[0071] (3) Preparation of 1-(6-bromohexyl)-1-methylpiperidine cationic grafted polybiphenyl (PBP-6-Pip) polymer

[0072] The PBP (1 g) prepared in step (1) was dissolved in DMSO (50 mL), and after the polymer was completely dissolved, excess side chain piperidine cation Br-6-Pip obtained in step (2) was added for quaternization. Reaction; after 72 hours of reaction at 90 °C, the solution was spin-dried to obtain a crude side-chain piperidine cation-grafted polybiphenyl solid; the crude product was washed with ethyl acetate and deionized water to remove the remaining Br-6- Pip, suction filtration, oven dry to obtain pure 1-(6-bromohexyl)-1-methylpiperidine cationic grafted polybiphenyl (PBP-6-Pip) polymer; as Figure 4-2 shown, is the general structure of the 1-(6-bromohexyl)-1-methylpiperidine cationic grafted polybiphenyl (PBP-6-Pip) polymer prepared in Example 2 of the present invention;

[0073] (4) Preparation of 1-(6-bromohexyl)-1-methylpiperidine cation-grafted polybiphenyl (PBP-6-Pip) alkaline membrane

[0074] The 1-(6-bromohexyl)-1-methylpiperidine cation-grafted polybiphenyl (PBP-6-Pip) polymer (1 g) obtained in step (3) was dissolved in DMSO (10 mL), A certain concentration of casting liquid is prepared, and then the casting liquid is cast or cast on a heat-resistant glass plate, cured, peeled off, and finally, the obtained alkaline film is immersed in a 2M NaOH aqueous solution for 48 hours to obtain the final film. 1-(6-Bromohexyl)-1-methylpiperidine cation-grafted polybiphenyl (PBP-6-Pip) basic membrane in hydroxide form.

[0075] Example 3

[0076] The preparation of 1-(8-bromooctyl)-1-methylpiperidine cationic grafted polybiphenyl (PBP-8-Pip) alkaline membrane, such as Figure 4-3 shown, is the preparation flow chart of 1-(8-bromooctyl)-1-methylpiperidine cation-grafted polybiphenyl (PBP-8-Pip) alkaline membrane in Example 3 of the present invention; the specific preparation The process is as follows:

[0077] (1) Preparation of polybiphenyl (PBP)

[0078] With embodiment 1;

[0079] (2) Preparation of 1-(8-bromooctyl)-1-methylpiperidine (Br-8-Pip)

[0080] 1,8-Dibromooctane (1.75 mL), N-methylpiperidine (1 mL), and ethyl acetate (20 mL) were added to a round-bottomed flask, and nitrogen was passed through to fully react to obtain a white solid precipitate. Filtration, purification with ethyl acetate, removal of excess reactant, and drying yielded the side chain piperidine cation 1-(6-bromohexyl)-1-methylpiperidine (Br-8-Pip);

[0081] (3) Preparation of 1-(8-bromooctyl)-1-methylpiperidine cationic grafted polybiphenyl (PBP-8-Pip) polymer

[0082] The PBP (1 g) prepared in step (1) was dissolved in DMSO (50 mL), and after the polymer was completely dissolved, excess side chain piperidine cation Br-8-Pip obtained in step (2) was added for quaternization. Reaction; after 72 hours of reaction at 90°C, the solution was spin-dried to obtain a crude side-chain piperidine cation-grafted polybiphenyl solid; the crude product was washed with ethyl acetate and deionized water to remove the remaining Br-8- Pip, suction filtration, oven dry to obtain pure 1-(8-bromooctyl)-1-methylpiperidine cationic grafted polybiphenyl (PBP-8-Pip) polymer; as Figure 4-3 shown, is the general structure of the 1-(8-bromooctyl)-1-methylpiperidine cationic grafted polybiphenyl (PBP-8-Pip) polymer prepared in Example 3 of the present invention;

[0083] (4) Preparation of 1-(8-bromooctyl)-1-methylpiperidine cation-grafted polybiphenyl (PBP-8-Pip) alkaline membrane

[0084] The PBP-8-Pip polymer (1 g) obtained in step (3) was dissolved in DMSO (10 mL) to prepare a casting solution with a certain concentration, and then the casting solution was cast or cast on a heat-resistant glass plate Finally, the obtained alkaline film was soaked in 2M NaOH aqueous solution for 48h to obtain the final PBP-8-Pip alkaline film in the form of hydroxide.

[0085] Use nuclear magnetic resonance spectrometer (Bruker AV 400, 400MHz) to characterize the products prepared in Examples 1-3 of the present invention, and its resonance frequency is 400MHz, such as Figure 5shown, is the nuclear magnetic structure diagram of the polydiphenylene and the respective side-chain piperidine cation-grafted polybiphenyl polymers prepared in Example 1-3 of the present invention; wherein, a is the step in Example 1-3 of the present invention (1) NMR structure diagram of the prepared polybiphenyl (PBP); b is the cationic graft of 1-(3-bromopropyl)-1-methylpiperidine prepared in step (3) in Example 1 of the present invention NMR structure diagram of type polybiphenyl (PBP-3-Pip) polymer; c is the cationic graft of 1-(6-bromohexyl)-1-methylpiperidine prepared in step (3) in Example 2 of the present invention NMR structure diagram of type polybiphenyl (PBP-6-Pip) polymer; d is 1-(8-bromooctyl)-1-methylpiperidine cationically coupled to 1-(8-bromooctyl)-1-methylpiperidine prepared in step (3) in Example 3 of the present invention NMR structure diagram of the branched polybiphenyl (PBP-8-Pip) polymer; the individual polymers can be confirmed by the NMR structure diagram.

[0086] TGA Q500 analyzer (METTLER, TGA/DSC3+) was used to analyze the thermal stability of the products of Examples 1-3 of the present invention. Before the test, the samples were dried at 80°C for 48h, and the heating rate during the test was set to 10°C/min. The temperature range is 30-800°C, and the results are as follows Image 6 As shown, the alkaline membranes prepared in Examples 1-3 have similar degradation curves, which can be roughly divided into three stages: the first stage of weight loss below 155 °C is attributed to the residual moisture and solvent in the membrane The second stage at around 200–370 °C is caused by the decomposition of piperidine cations; the third stage of weight loss detected above 400 °C corresponds to the decomposition of backbone PBP. The above results show that the PBP-n-Pip series membranes prepared in Examples 1-3 of the present invention all have good thermal stability, and can fully meet the temperature requirements of the daily work of the fuel cell.