| Polyhedral oligomeric silsesquioxanes (POSS), having an inner cage with aninorganic silicon and oxygen framework which is covered externally by organicsubstituents, are cube-octameric molecules of nanoscale dimensions that may befunctionalized with reactive groups suitable for the synthesis of neworganic-inorganic hybrids as well as their application in optics, catalysis, andelectronics. In the past years, there has been ample literature to report the preparationof POSS-containing composites，including (i) POSS macromers bearing singlepolymerizable (or reactive) groups were grafted onto polymer chains;(ii) a reactivegrafing approach copolymerize with other monomers’ ends of organic polymers; and(iii) Prepare POSS-containing nanocomposites by the use of multi-functional POSSmacromers. POSS-containing composites obtained by first method, sometimes,exhibit an ill defined structure as incomplete grafting reaction. The second methodcould get the end modification composite, but only capped POSS macromers bearingsingle polymerizable (or reactive) group to the terminal of polymer chains is difficultto get the polymer with high POSS content. For the third method, there have beensome reports on the preparation of POSS-containing nanocomposites by the use ofmulti-functional POSS macromers. Because of multiple site on POSS with equivalentreactivity it is rather difficult to introduce only two functional groups, sopolymerization from the POSS monomers typically generates insoluble cross-linkedpolymers from small amounts of POSS containing more than two functional groups.And the cross-linked polymers cannot be processed as linear polymers. It is expectedthat linear organic-inorganic copolymers with POSS in the main chains can beaccessed via one-step polymerization while difunctional POSS macromers are utilized.Double-decked silsesquioxane (DDSQ) is a kind of difunctional POSS. For manyapplications, the preparation of thermoplastic organic-inorganic hybrids with DDSQin the main chains is desirable owing to the simplicity in thematerials processing andthe good symmetry to ensure high chain regularity of the hybrids. Poly(aryl ether sulfone)(PES) is an engineering thermoplastic used in aviation,military, and electronic field. PES exhibits many excellent properties, such as highservice temperature, resistance to organic solvents, as well as certain mechanicalproperties. However, as common with traditional thermoplastics, PES could behave inpoor hydrophobic(CA=80o) manner as O=S=O and ether bond. Moreover, lowdielectric constant of PES(k=3.0) can not be satisfied the demand in electronicpackaging and large scale integrated circuit. According to the previously reports，incorporating DDSQ into the main chains of polymer can significant lower thedielectric constant as DDSQ having an inner cage with an inorganic silicon andoxygen framework. However,the synthesis of copolymers with DDSQ in the mainchains are highly rigid because their bulky side groups may interfere with each other,which give rise to very low number of macromolecular conformations and themacromolecular have poor toughness. With the same compositions of DDSQpolydimethysiloxanes (PDMSs) serve as good toughening and hydrophobic agents fororganic-inorganic copolymersbecause of the silicon-based spiral arrangement of themolecular chains, which lead to strong chain flexibility and high surface energy.So, in this study, two dihydroxy terminated cage (DDSQ) and linear (PDMS)organosiloxane oligomers were used to copolymerize with4-chlorobenyl sulfone toobtain poly(aryl ether sulfone) containing cage and linear organosiloxane (Si-PES)through one-step high-temperature solution method. A research was conducted toinvestigate the effect of organosiloxane structure on the dielectric of hybridcopolymers. The free volume of chain entanglement and interfacial polarization ofPOSS and organic phase in microcosmic polymers were also discussed. Moreover,thermal behavior, crystallization behavior, and surface properties were investigated.Cl-terminated copolymer cotaining linear and cage siloxane in the main chain wereobtained by controlling the feed ratio of sileugenol and fluorine sulfone. Theterminal-modified with various amounts of organic silicon monomer were furtherstudied at effct of the content and structure to hydrophobic silicone polymer. Thispaper mainly has two parts:The first part, octamethyl cyclotetrasiloxane as a monomer, silicone-tetramethyl-dihydro as capping agent, an acid catalyst microspheres styrenecationic were used in catalysting ring-opening polymerization, a fixed chain lengthsdihydrotestosterone capped linear polymethylsiloxane were synthesized. Thenhydrogenated product with eugenol siloxane to obtain a bisphenol terminated linearsilicone monomer. Then double-decker type four silicon alcohol were used tosynthesis organic silicon bisphenol monomer according to our group’s reports before.The two kinds of different structures, same elemental composition of organic siliconbisphenol monomers were used to react with4,4-dichlorobenyl sulfone to gain,aseries of linear and cage containing backbone organic silicone polyether sulfonerandom copolymers. At the same time, Cl-terminated copolymer cotaining linear andcage siloxane in the main chain were obtained by controlling the feed ratio ofsileugenol and fluorine sulfone.The second part was discuss and study the dielectric and hydrophobic propertiesof the prepared copolymer. Such as the effct of the polymer microscopic phasemorphology, polarization and the molecular chain conformation and otherpolymerization to the dielectric material impact performance. This provides a newway to further study the composition and structure of the organic silicone of PEShybrid material functional modifications. |
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