Functionalization Of Polyimide And Polyethersulfone Materials Via Trifluoromethylation And Quaternary Ammonium Salt Structural Derivation

Both as heat-resistant polymers,polyimides(PIs)and polyethersulfone(PES)are prepared by condensation polymerization,and share some similarities in structure and properties.The main chains of PIs and PES are composed of rigid skeleton with aromatic ring that endow materials with excellent thermal and mechanical properties and chemical stability,therefore widely used as high performance polymers.Meanwhile,PIs or PES have their own structural characteristics and limitations,necessitating the structural modification for improved application performance.Due to the presence of intermolecular and intramolecular charge transfer(CT)effect,PIs suffer from poor processability,which makes the material difficult to melt and dissolve,deep color,and relatively high dielectric constant,limiting the further application of PIs.On the other hand,due to its excellent physiological inertia,PES is used as biomedical material,such as hemodialysis membrane.However,the hydrophobic structure of PES materials leads to the adsorption of platelet and protein on the surface of the materials,causing coagulation and inflammation.Therefore,it is necessary to further increase the biological / blood compatibility of the materials to improve the clinical reliability of medical devices.In view of the above problems,the structure of trifluoromethyl and dimethylamine have been introduced into PI backbone to improve the solubility and transparency.The bulky structure of trifluoromethyl and dimethylamine would incease the inter-chain spacing distance,which makes the solvent easier to access the polymer chains and improves its processability.In addition,ether linkage has been introduced into PI molecule,and its flexible structure would increase the free rotation of macromolecular chain,inhibit the CT interaction,and improve the flexibility and solubility of PIs.At the same time,quaternary ammonium salt and sulfonate structure have been introduced into PES to improve the hydrophilicity of the materials and impart certain antibacterial properties.Quaternary ammonium salt and sulfonate group are typical hydrophilic structure,which can inhibit the adsorption of protein and platelets on the surface of the material.The cationic nature of quaternary ammonium salt absorbs anionic type bacteria through the isoelectric interaction and hydrogen bonding forces,inhibiting their growth of bacteria to achieve antibacterial effect.In the research of this dissertation,fluorinated and dimethylamine structure have been introduced into PI backbone,and quaternary ammonium salt and sulfonate group into PES backbone to improve the performance of the modified polymer materials.This dissertation is composed of the following two parts:The first part relates to the investigation on PIs.In this part,4,4'-biphenol(BP)has been used as raw materials to react with formaldehyde and dimethylamine in the ethanol reaction solution,to offer 3,3'-bis(bis(N-N-dimethyl)-methyl)biphenol(BBMAMBP)that reacted with 2-chloro-5-nitrobenzotrifluoride via nucleophilic substitution to give the dinitro compound1,1'-(4,4'-bis(4-nitro-2-(trifluoromethyl)phenoxy)-[1,1'-biphenyl]-3,3'-dimethyl)Bis(N,N-dimethylmethylamine)(BNPDMA),followed by reduction by hydrazine with palladium on carbon to generate the diamine monomer4,4'-((3,3'-bis((dimethylamino)methyl)-[1,1'-biphenyl]-4,4'-bis(oxy))bis(3-(Trifluoromethyl)aniline)(BMA3FA).Coplymerization with ODPA have been carried out by doping BMA3 FA with ODA in different proportions to give PI films via two-step approach.It is found that the modified PI film has good hydrophobicity and good permeability.The modified PI film shows good hydrophobicity,the with the contact angle data dropping to 65.9°.As the moiety of zwitterionic diamine increases,the contact angle of the PI film becomes larger.The overall optical transparency remains above 76%,indicating that good optical properties.The second part relates to the investigation on PES.In this part,3,3'-bis(bis(N,N-dimethyl)-methyl)biphenol(BBMAMBP)has been reacted with 4,4-dichlorodiphenyl sulfone via condensation polymerization to synthesize PES,then the resulting PES is further reacted with 1,3-propane sultone to generate quaternary ammonium salt and sulfonate modified PES.At the same time,Mannich reaction between 2,5-dimethylphenol with 4,4-dimethylaminobenzaldehyde produces the dimethylaminated biphenol4,4'-((4-(dimethylamino)phenyl)methylene)bis(2,5-dimethylphenol),and the resulting PES has been further reacted methyl iodide to convert into PES containing quaternary ammonium salt.The hydrophilicity of the modified PES membrane has gained improved hydrophilicity and antibacterial properties.The contact angle of control polyethersulfone is 103.3°,and the modified polyethersulfone is 42.4°.It is found by antibacterial experiments that control polyethersulfone does not have any antibacterial properties,whereas,the modified zwitterionic PES exhibits its antibacterial efficiency high as 50%.