Synthesis And Properties Of Polyethersulfone Polydimethylsiloxane Block Copolymers

A large range of applications are directly dependent on thesurface characteristics of polymeric materials such as friction,permeability,adhesion,biocompatibility,etc.Chemical,photochemicaland plasma treatments are currently used in order to increase thepolarity of polymer surfaces. In contrast, the surface energy of apolymer matrix is efficiently decreased by the addition of silicon-and fluorine-rich compounds.. Polyethersulfone(PES) is widely used as an important class ofengineering thermoplastics which exhibits many excellentproperties,such as good resistance to organic solvent,hydrolyticstability,high Tg and superior thermo-oxidative stability; Theincorporation of polyimethyl iloxane(PDMS) phases is desirable asa method to improve properties such as impact resistance, toughness,elongation at break.In addition , PDMS may lead to surfacemodification due to their surface energy lower than of most othermaterials.The aim of this paper was to improving surface propertyof PES.Such block copolymer(PES-PDMS) has been previously described inthe literature and may be achieved by different synthesis approaches,by copolymer condensation reaction of preformed hydroxy-terminatedpolyethersulfone oligomers and silylamine-terminated PDMS, or byaddition reaction of hydrosilane (Si-H) to vinyl end groups ofaromatic PES oligomers. Consequently,the block copolymer containsSi-O-C or Si-C linkages between two distinctly different segments.The Si-O-C unit is found to be very susceptible to hydrolysisin copolymers versus Si-C type linkage. In our research,we exploitedthe hydrosilylation reaction to form Si-C linkages between PES andPDMS. Hydrosilylation is a very convenient and efficient method forthe syntheses of a variety of organosilicon compounds not only forthe study of organosilicon chemistry, but also for silicon-basedmaterials.Platinum and rhodium catalysts have been the mostfrequently used catalysts among all the metal-based catalysts forthe hydrosilylation.The reaction of chloroplatinic acid with1,3-divinyltetramethy-ldisiloxane gave a catalyst of platinumcomplexes. The activity of complexes in the reaction of mold compoundwith hydrosilyl-terminated PDMS oligomer was discussed,and it wasfound that the catalyst had high activity. At the same time,allylether groups showed high reactivity with Si-H. Further, addition of Si-H to allylether groups occurred mostlyin an anti-Markovnikov manner.Allylether-terminated PESs havebeen obtained by reaction of hydroxy-PES with allyl bromide.Finally,block polymers of PES-PDMS have been prepared byhydrosilylation of allylether-terminated PES with hydrosilyl-terminated PDMS us a Pt catalyst. To prove our assumption, at first we characterized and analyzedthe mold compound and polymer through FTIR,DSC,1H-NMR.The finalresults are consistent with prediction.The average moleculer weightof hydrosilyl-terminated PDMS and allylether-terminated PES wereinvestigated by H-NMR. 1 We employed FTIR instrument to trace the hydrosilylationreaction. The IR spectra of PES-PDMS block copolymers demonstratedthe conversion of Si-H end groups to Si-C linkages by the completedisappearance of 2130cm-1 absorption bond characteristic of thehydrosilyl -terminated PDMS and appearance of a large absorptionwhich is not present in the spectra of PES.1H-NMR was used todetermine the composition of the block polymers from the ratio ofthe peak intensities of PDMS methyl proton at δ=0.07ppm and thearomatic proton of PES atδ=7.82ppm. Finally,the thermal stability and surface property of blockcopolymers were studied. The thermal stability of PES-PDMS wasstudied by TGA. The comparison of the values of the temperature 5%weight loss (468-445℃) for the PES with that of PES-PDMS indicatedthat the thermal stability of block copolymers decreased due toincorporation of PDMS units. In addtion the surface property of block copolymers has beenstudied by X-ray Photoelectron Spectroscopy(XPS) and contact angle...