Three polycaprolactam samples modified by 0.05—0.50% polyphenylquinoxaline(PPQ)by weight were prepared.Their structure and mechanical properties were characterized by FT-IR, SEM, density, tensile, impact, DTAand visc...Three polycaprolactam samples modified by 0.05—0.50% polyphenylquinoxaline(PPQ)by weight were prepared.Their structure and mechanical properties were characterized by FT-IR, SEM, density, tensile, impact, DTAand visco-elastic method, PPQ induced the formation of 'crystal grains' distributed evenly over nylon spherulites in modified samples, which were observed for the first time, and strengthened modified samples. Modified nylons had higher crystallinities, higher T_g, more nearly perfect spherulites than MC nylon itself, and showed typical reinforcing effect on mechanical properties.展开更多
A novel fluorene-bridged tetraketone monomer,9,9-bis[(4-benzilyloxy)phenyl]fluorene(FLTK) was synthesized and characterized.The tetraketone was polymerized with various aromatic tetraamines to afford a series of polyp...A novel fluorene-bridged tetraketone monomer,9,9-bis[(4-benzilyloxy)phenyl]fluorene(FLTK) was synthesized and characterized.The tetraketone was polymerized with various aromatic tetraamines to afford a series of polyphenylquinoxalines(PPQs).The obtained polymers were found to be soluble in common organic solvents such as N-methyl-2-pyrrolidone(NMP),chloroform and m-cresol.Flexible and tough PPQ films obtained by spin-casting their NMP solutions exhibited tensile strengths higher than 60 MPa.The films also demonstrated good thermal stability up to 500℃in nitrogen and glass transition temperatures higher than 280℃.In addition,the PPQ films exhibited good hydrolytic stability. High surface and volume resistivity retentions were achieved for the films after immersion or boiling in water for 24 h.展开更多
Since the electrical conductivity of polyacetylene was published in 1977, a lot of work has been devoted to the synthesis of new organic conducting or semiconducting materials. A new development in the field of electr...Since the electrical conductivity of polyacetylene was published in 1977, a lot of work has been devoted to the synthesis of new organic conducting or semiconducting materials. A new development in the field of electrically展开更多
Although polyimide (PI) and polyphenylquinoxaline (PPQ) are both heat resistant polymers, their hydrolytic stabilities are quite different. In this paper, the electron densities of two model compounds——N-phenylphtha...Although polyimide (PI) and polyphenylquinoxaline (PPQ) are both heat resistant polymers, their hydrolytic stabilities are quite different. In this paper, the electron densities of two model compounds——N-phenylphthalimide and 2,3-diphenylquinoxaline are calculated by moans of CNDO/2 method. On the other hand, hydrolysis of model compounds and polymers is carried out. The theoretical calculation and experiments both prove that PPQ has excellent hydrolytic stability while PI is completely hydrolyzed under the same experimental condition. The mechanism of hydrolysis is also predicted.展开更多
The preparation of conducting PPQ film was first reported in the previous paper. It is very interesting that this film is highly sensitive to moisture in air. The hydration and dehydration of the film are accompanied ...The preparation of conducting PPQ film was first reported in the previous paper. It is very interesting that this film is highly sensitive to moisture in air. The hydration and dehydration of the film are accompanied by change not only in color but also in conductivity and UV-visible spectrum. The conducting PPQ is reduced to PPQ and loses its conductivity after being soaked in water.展开更多
基金Project supported by the National Natural Science Foundation of China.
文摘Three polycaprolactam samples modified by 0.05—0.50% polyphenylquinoxaline(PPQ)by weight were prepared.Their structure and mechanical properties were characterized by FT-IR, SEM, density, tensile, impact, DTAand visco-elastic method, PPQ induced the formation of 'crystal grains' distributed evenly over nylon spherulites in modified samples, which were observed for the first time, and strengthened modified samples. Modified nylons had higher crystallinities, higher T_g, more nearly perfect spherulites than MC nylon itself, and showed typical reinforcing effect on mechanical properties.
基金supported by the National Natural Science Foundation of China(Nos.51873104 and 51011120100)
文摘A novel fluorene-bridged tetraketone monomer,9,9-bis[(4-benzilyloxy)phenyl]fluorene(FLTK) was synthesized and characterized.The tetraketone was polymerized with various aromatic tetraamines to afford a series of polyphenylquinoxalines(PPQs).The obtained polymers were found to be soluble in common organic solvents such as N-methyl-2-pyrrolidone(NMP),chloroform and m-cresol.Flexible and tough PPQ films obtained by spin-casting their NMP solutions exhibited tensile strengths higher than 60 MPa.The films also demonstrated good thermal stability up to 500℃in nitrogen and glass transition temperatures higher than 280℃.In addition,the PPQ films exhibited good hydrolytic stability. High surface and volume resistivity retentions were achieved for the films after immersion or boiling in water for 24 h.
基金Project supported by the National Natural Science Foundation of China
文摘Since the electrical conductivity of polyacetylene was published in 1977, a lot of work has been devoted to the synthesis of new organic conducting or semiconducting materials. A new development in the field of electrically
文摘Although polyimide (PI) and polyphenylquinoxaline (PPQ) are both heat resistant polymers, their hydrolytic stabilities are quite different. In this paper, the electron densities of two model compounds——N-phenylphthalimide and 2,3-diphenylquinoxaline are calculated by moans of CNDO/2 method. On the other hand, hydrolysis of model compounds and polymers is carried out. The theoretical calculation and experiments both prove that PPQ has excellent hydrolytic stability while PI is completely hydrolyzed under the same experimental condition. The mechanism of hydrolysis is also predicted.
基金Project supported by the National Natural Science Foundation of China
文摘The preparation of conducting PPQ film was first reported in the previous paper. It is very interesting that this film is highly sensitive to moisture in air. The hydration and dehydration of the film are accompanied by change not only in color but also in conductivity and UV-visible spectrum. The conducting PPQ is reduced to PPQ and loses its conductivity after being soaked in water.
