Synthesis And Properties Of Cycloolefin Metathesis Copolymer And Its Composite For Shape Memory Investigation

It is well known that norbornene-based polymers are a kind of amorphous polymer with high thermal stability, optical transparency, low dielectric constant, and shape memory abilities in broad applications. However, as used in shape memory materials, PNBE is required highly molecular weight to attain a certain mechanical strength that brings about issues in processing. Based on the consideration above we design two kinds of shape memorable copolymers.One is with PCL side chains and cyano functional groups attached to PNBE backbones in the combination of ROP and ROMP. On the one hand, it forms the microphase segregation structure which is essential for the shape memory effect and improves the mechanical strength of PNBE for choosing the crystalline PCL as side chains to amorphous PNBE backbones. On the other hand, the copolymerization with norbornene derivatives could improve the brittle and poor processible properties of PNBE and the incorporation of functional cyano group in the polymer could dramatically enhance the strength of the materials since cynao group with strong polarity makes the polymer chain more liable to aggregate. As a result, this kind of material offers an opportunity for manufacturing through the thermoplastic molding. X-ray diffraction pattern indicated the copolymer has two phases a typical amorphous pattern of PNBE and the crystallinity of PCL, a Tm is measured by DSC at 55℃which is a Ttrans of the copolymer. The shape recovery time is within 5 min at 90℃. The stress-strain curves indicated the copolymer resembles the semicrystalline polymers such as polyethylene and polypropylene. The rapidly fall of the E'in DMA indicates that the copolymer exhibits the good shape fixity on cooling and the large shape recovery upon heating. Moreover, a capacity of the induction heating that remotely triggered by an alternating magnetic field has been obtained by a facile method to disperse modified Fe3O4 nanoparticles in the copolymer matrix. We actualize the copolymer sensitive to magnetic field on the same time decrease shape recovery induction time at about 186 s by increase thermal conductivity of modified Fe3O4 nanoparticles.The other one is based on the polymeric backbone of NBE derivates and COE. In consideration that pure SMPs usually exhibit lower modulus, the inorganic POSS is incorporated into the polymer as side chain that dramatically improves mechanical strength and thermomechanical properties which proven by tension test and TGA that with higher POSS content excels in mechanical strength and thermostability. Ttrans of P(COE-co-NBEDCA-g-POSS10) and P(COE-co-NBEDCA-g-POSS2o) are 78℃and 68℃from DMA. It is demonstrated that the specimen regains its original shape with 58 s at 98℃and 44 s at 88℃.