The Synthesis Of Cyclodextrin Based Inclusion Complex And Its Applications In Modifying Polyoxymethylene

Polyoxymethylene (POM) has been widely used in various fields due to its excellent mechanical properties. Significant attention has been paid on the modifications of POM because of the brittleness at room temperature and low thermostability. In this work, we designed and synthesized a series of inclusion complexes (ICs) based on CDs and furtherly applied the obtained inclusion complex to the modifications of POM. ICs are expected to be new multi-functional modifiers because of the unique supramolecular assembled structure.We carried out the experiments focusing on three main aspects:the synthesis of ICs, characterization of ICs, and their applications on modifying POM. The main researches and conclusions are as follows:(1) The synthesis of ICs:According to the principle of spacial size matching, we have succeeded in preparing the inclusion complex of poly(ethylene glycol- propylene glycol- ethylene glycol) (PEG-PPG-PEG, EPE) and β-cyclodextrin β-CD) (IC-EPEs), POM and α-cyclodextrin (α-CD) (IC-POMs), thermoplastic polyurethane (TPU) and β-CD (IC-TPUs);(2) The characterizations of ICs:Detailed characterizations of the prepared ICs were carried out by XRD, FTIR, TGA, DSC, and WAXD. It was found that IC-EPEs, IC-POMs and IC-TPUs crystals adopted the channel structure. Especially, we have compared the properties of the formed ICs with the guest polymers:For IC-EPEs, the thermostability of both host and guest molecules were improved compared with those in pure state; the crystallize ability of IC-POMs was improved attribute to the pre-ordered structure of POM chain segments which were freed from cyclodextrins; TPUs were strengthened by the CDs due to the new crosslinking point of assembled inclusion complex.(3) The modifications of ICs on POM:We fabricated POM/IC-EPEs, POM/IC-POMs and POM/IC-TPUs composites by simply incorporating the ICs into POM matrix by melt blending. It was found that IC-EPEs strengthened POM matrix greatly and improved the thermostability simultaneously. The incorporation of IC-POMs hardly influenced the mechanical properties and crystallization of POM, but increased the initial degradation temperature at nitrogen atmosphere. The POM/IC-TPU (1-1) composites showed excellent stiffness-toughness balance with the initial degradation temperature increased as high as 40 ℃ at nitrogen atmosphere. Further studies showed that the special "soft shell-hard core" structure of the inclusion complex contributed to the excellent properties:the "soft shell" toughened the POM matrix, while the "hard core" compensated for the sacrifice of strength and modulus resulted from elastomer toughened plastic, meanwhile, the "hard core" strengthened the matrix as well. In addition, the cooperation of amino and hydroxy groups was realized by inclusion complex and such combination significantly enhanced the thermostability of POM.