Synthesis And Characterization Of Octaarmed Star-shaped Polyester And Miscibility, Phase Behavior And Specific Intermolecular Interaction In Epoxy Resin Blends

A novel octaarmed star-shaped poly(L-lactide) (PLLA) with polyhedral oligomeric silsesquioxane (POSS) core was synthesized via ring-opening polymerization of L-lactide (LLA) with octa(3-hydroxylpropyl) polyhedral oligomeric silsesquioxane (POSS) as an initiator. It is found that the arm length of organic-inorganic PLLA can be well controlled according to the molar ratios of L-lactide to POSS. The structure and molecular weights of the star-shaped PLLA were characterized by means of proton nuclear magnetic resonance (1H NMR) and gel permeation chromatography (GPC). Differential scanning calorimetry (DSC) indicated that the star-shaped PLLA samples are also crystallizable but possess lower melting points and crystallinity than control linear PLLA. The wide angle X-ray diffraction showed that the formation of octa-armed star topology does not alter the crystalline structures of PLLA. In term of thermogravimetric analysis (TGA), it is identified that the thermal stability of PLLA is effectively enhanced with the introduction of the POSS core.A novel octaarmed star-shaped poly(ε-caprolactone) (PCL) with polyhedral oligomeric silsesquioxane (POSS) core was synthesized. MOCA cured ER/star-PCL and ER/linear-PCL were investigated by using DSC, FTIR. The two binary blends are judged to be fully miscible in the amorphous state as evidenced by the single, composition-dependent glass transition temperatures in terms of differential scanning calorimetric (DSC) results. The Tg of the star-PCL blends were higher than those of the linear ones, implying that the degree of homogeneity of the star blend system is higher than that of the linear blend due to the star structure.