链间氢键调控对聚丙烯酸-聚氧化乙烯复合物薄膜力学性能的影响

The Effect of Interchain Hydrogen Bond on the Mechanical Properties of Poly(acrylic acid)-Poly(ethylene oxide) Complex Films

采用可调节式涂膜器制备了聚丙烯酸(PAA)和聚氧化乙烯(PEO)复合物薄膜.通过改变薄膜组分和酸处理调控PAA与PEO间氢键相互作用.利用傅里叶红外光谱、示差扫描量热仪、X射线衍射仪和力学拉伸仪对氢键相互作用、薄膜聚集态结构和力学性能进行表征.研究结果表明,氢键相互作用的强弱影响着材料的聚集态结构和力学性能,当PAA与PEO分子间相互作用较弱时,PEO结晶,薄膜呈现塑形材料的性质,当PAA与PEO分子间相互作用较强时,氢键能完全抑制PEO结晶,薄膜呈现高弹性.

Poly(acrylic acid)(PAA)and poly(ethylene oxide)(PEO)can form hydrogen-bonded polymer complex.A PAA/PEO homogenous solution can be obtained by adding NaOH into the mixture to restrict the hydrogen bonding between PAA and PEO.First,PAA was dissolved in 20 mL of NaOH aqueous solution and PEO was dissolved in 20 mL of distilled water with the total mass of PAA and PEO of 3.48 g.After stirred for 6 h and centrifuged in the deaeration system at 3500 r/min for 10 min,the mixture was blade coated onto a PTFE plate through an adjustable film applicator with the thickness of 2 mm,and dried in the ambient environment to obtain PAA/PEO films.The effects of film composition and acid treatment on the structures and mechanical properties of the films were studied by Fourier transform infrared spectroscopy(FTIR),differential scanning calorimetry(DSC),wide angle X-ray diffraction(XRD),and mechanical streching machine.The crystallization behavior of PEO and the mechanical properties of the films showed strong dependence on the hydrogen bonding between PAA and PEO.The elongation increased while the tensile strenghth and the Young’s modulus decreased first and then increased with the increasing PEO content in the films.After incubation in a pH=1 solution for 3 min,the hydrogen bonding between PAA and PEO was enhanced.Compared with the film without acid treatment,the flexibility of the film was greatly enhanced after acid incubation.In particular,Young’s modulus of the film(n(AA):n(EO)=1:3)before acid treatment was 426 MPa while it declined to 3 MPa after acid incubation.Namely,when the hydrogen bonding between PAA and PEO became weak,PEO would crystallize and the film performed like a plastic material.When the hydrogen bonding between PAA and PEO became strong,the crystallization of PEO was restricted and the film acted as a rubber material.