反相气相色谱表征可溶性聚酰亚胺的表面性质

采用反相气相色谱技术,将正己烷、正庚烷、正辛烷、正壬烷作为非极性分子探针,乙醚、丙酮、三氯甲烷作为极性分子探针在50℃、60℃、70℃和80℃条件下测定了可溶性聚酰亚胺HQDPA-DMMDA的表面色散自由能与表面Lewis酸碱性质.HQDPA-DMMDA在50℃、60℃、70℃和80℃的表面色散自由能分别为34.37、31.80、29.50和27.64 mJ/m2,自由能随温度的升高而线性降低.实验发现,HQDPA-DMMDA为弱的Lewis两性聚合物材料,其Lewis酸常数Ka为0.4115,碱常数Kb为0.5812.

SURFACE CHARACTERIZATION OF SOLUBLE POLYIMIDE BY INVERSE GAS CHROMATOGRAPHY

Inverse gas chromatography(IGC) is a new characterizing method for surface properties in polymer field.The main difference between GC and IGC is that the interested species is the polymer material acting as the stationary phase in IGC column.Probe solvents with known properties are injected in column.For the interactions between probe solvents and polymer stationary phase are different,the surface properties of polymer can be determined from the retention volume of probe solvents.In this work,surface properties of soluble polyimide HQDPA-DMMDA were quantitatively analyzed by the IGC method.Four n-alkanes(C_6,C_7,C_8 and C_9) were chosen as non-polar probes to characterize the dispersive component of free energy.Trichloromethane(CHCl_3),ethyl ether and acetone were chosen as polar probes to detect the Lewis acid-base parameters.It was found the dispersive component of free energy of HQDPA-DMMDA was 34.37 mJ/m~2,31.80 mJ/m~2,29.50 mJ/m~2 and 27.64 mJ/m~2 at 50℃,60℃,70℃ and 80℃,respectively.The surface free energy decreased linearly with increasing temperature.The Lewis acidic number K_a of HQDPA-DMMDA was 0.4115,and basic number K_b was 0.5812.The result meant that HQDPA-DMMDA was a weak Lewis amphoteric polymer.