Synthesis And Properties Of A Degradable Heat-Resistant Polymer Material Containing Acetal Structure

In this study,polyimide and polyethersulfone were synthesized with degradation and heat resistance.Aromatic polyimide(PIs)is one of the most important high-performance materials with good mechanical properties,excellent thermal stability,high glass transition temperature and good organic solvent resistance.,its low solubility in most organic solvents makes PI material processing difficult,so the application of PI in some fields is limited.This experiment achieves the desired effect through the following structural modification: Triaryl imidazole groups that can improve thermal stability are introduced into the main Chain,and polymers are prepared by blending condensation polymerization to maintain thermal properties.By introducing non-coplanar spiral acetal structure,the polyimide can be degraded under acidic conditions,The application of polyimide in environmental protection material is expanded.Firstly,benzil is taken as a raw material to react with2-chloro-5-nitrobenzaldehyde,thus synthesizing 2-(2-chloro-5-nitrophenyl)-4,5-diphenyl-1H-imidazole(DPI).And then,aldol reaction occurs between p-hydroxybenzaldehyde and pentaerythritol which is cheap and readily available to obtain 2,4,8,10-tetraoxygroup-3,9-2-(4-hydroxyphenyllactic)aspiro [5,5]undecane(PHOD).Nucleophilic substitution reaction happens between DPI and PHOD under the catalyzation of potassium carbonate to obtain a kind of binitro 2,4,8,10-tetraoxygroup-3,9-2 [(4-nitryl-2-(4,5-diphenyl-1H-imidazole-2-radical)phenoxyl] aspiro [5,5] undecane(BNDPIOD),which contains both acetal and imidazole.And it is involved in a reduction reaction to obtain diamine 2,4,8,10-tetraoxygroup-3,9-2 [(4-amino-2-(4,5-diphenyl-1H-imidazole-2-radical)phenoxyl] aspiro [5,5] undecane(BADPIOD).BADPIOD is mixed with ODA in different proportions,and then they are mixed with ODPA.Taking dewatered DMAc as solvent,two-step method is applied to perform condensation polymerization to obtain thin film.Secondly,a special engineering plastic,polyethersulfone,was prepared by reacting with 4,4 dichlorodiphenyl sulfone,using the previously prepared spiral-acetal diphenol as raw material.Due to the introduction of acetal,the modified polyethersulfone is sensitive to acid and can decrease the Solution under acidic conditions.Thirdly,using 1,1-bis[4-(4-pyridyloxy)phenyl]cyclohexane(BAPBP),which contains cardo alicyclic structure and pyridine heterocyclic ring groups and synthesized by our group.BAPBP polymerized with ODPA,6FDA,BPDA,BTDA respectively by traditional two steps to got PIs films.To characterize the PIs films,the result that,due to the introduction of pyridine heterocyclic,the thermal performance of materials is excellent,optical performance is better also.And alicyclic structure destroyed the close packing of molecular chain,reduced the crystallinity of molecular improve the processing performance of materials.