Preparation And Properties Of Cyclodextrin Modified Polysiloxanes

Polysiloxane has many excellent properties, such as low surface tension, good thermalstability, good physiologically inert and biocompatible, has been widely used as organic-inorganic materials. Cyclodextrins are one of the important host compounds of poly(pseudo)rotaxanes. Cyclodextrins are biocompatible，selectivie and regulated for the molecule.Assembly between cyclodextrin (CD) and polymer have attracted growing attention.In this paper, the different structures of amphiphilic polyether polysiloxanes wereprepared by functionalized modification. Assembly between different type of cyclodextrinsand polyether polysiloxanes were studied. The products were characterized by FT-IR,1H-NMR, DSC, XRD, DSC, TGA, et al. The specific programs are conducted from followingaspects.Firstly, the Octamethylcyclotetrasiloxane and Tetramethyl-dihydro-disiloxane are usedas raw materials to synthesize Hydrideterminated polydimethylsiloxane (HPDMS). Themethod of this reaction is ion ring-opening polymerization with the activators Tetramethylammonium hydroxide silicon alkoxide and Trifluoromethanesulfonic acid. Assemblybehavior between β-CD, γ-CD and HPDMS were discussed.Secondly, Amphiphilic polyether polysiloxane block copolymer (PEO-PDMS-PEO) wassynthesized by hydrosilylation, using HPDMS and polyoxyethylene allyl ether (APEG).FT-IR spectrum,1H-NMR spectrum and surface tensiometer were used to analyse the blockcopolymer.Thirdly, inclusion reactions between α-CD, γ-CD and PEO-PDMS-PEO were discussed.The complex of α-CD and PEO-PDMS-PEO was channel crystalline and forms hydrogel. Theconcentration and ratio of the reactants could affect the hydrogel’s sol-gel transitiontemperature. The complex of γ-CD and PEO-PDMS-PEO formed precipitation. Under lowconcentration, γ-CD could make the surface tension of PEO-PDMS-PEO increased. Underlow concentration, with increasing γ-CD, PEO-PDMS-PEO’s turbid solution became clearand then became turbid again. γ-CD could identify PDMS segments and the complex ischannel crystalline. γ-CD could identify PEO segments, which had be confirmed by DSC and FT-IR. But we could not be sure the crystalline structure and whether one or two PEO chainswere included by γ-CD. When α-CD and γ-CD existed in system, γ-CD could identify PDMSsegments and α-CD could identify PEO segments. The complex of α-CD, γ-CD andPEO-PDMS-PEO was channel crystalline.Finally, the polyether grafted polysiloxane (PDMS-(PEO)4.5) was synthesized. Thecomplex of α-CD and PDMS-(PEO)4.5could form hydrogel, which was more stable thanPEO-PDMS-PEO because of the more PEO segments.