ADMET Polymerization Of Diene Ionomer With POSS Pendant Group And The Properties Of The Polymer

Acyclic diene metathesis (ADMET) has proven to be a versatile tool for the production of novel polymeric materials since the term was successfully demonstrated 20 years ago that it has found applications in different fields, such as polymer, material and medicinal chemistry et al. Polyhedral oligomeric silsesquioxane (POSS), as one of the inorganic/organic hybrid nanomaterials has attracted great attention both in science circles and in industrial quarters over the past decades because of its excellent physical and chemical properties. A variety of polymerization techniques have been used to prepare different types of POSS-containing hybrid polymers, include conventional free radical polymeriztion, nitroxide-mediated radical polymerization (NMP), atom transfer radical polymerization (ATRP), reversible addition fragmentation chain transfer (RAFT) polymerization, ring-opening metathesis polymerization (ROMP), and anionic polymerization et al. However, to the best of our knowledge, the use of ADMET polymerization to product POSS-containing polymers has not been reported yet. Based on the above described research status, in this contribution, we report the first investigation of the ADMET polymerization of the POSS-containingα,ω-diene diene monomers and ionomers using Grubbs second generation catalyst (GrubbsⅡ) to prepare novel POSS hybrid polyethylene.1H NMR,13C NMR, gel permeation chromatography (GPC), thermogravimetry (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), atomic force microscope (AFM) were used to fully characterize the investigated systems.According to the design idea, we synthesized two types of diene monomers N,N'-Bis (butenyl)-aminopropyl POSS (monomer 1) and N,N-Bis (10-undecenyl)-aminopropyl POSS (monomer 2) with POSS as pendant group from the initial material, POSS-NH2, by one-step of nucleophilic substitution using 4-bromo-l-butene and 11-bromo-1-undecene as the subsitute reactants, respectively. The structures were characterized with 1H NMR and 13C NMR to confirm as the target products. The ADMET behavior of the above prepared monomers was investigated in toluene with GrubbsⅡunder different reaction time. Molecular weight and Polydispersity Index (PDI) of the corresponding polymers were characterized by GPC. The results showed that no polymerization occurred of monomer 1 while the polymerization degree of monomer 2 was not high. We speculated the results were caused by the bulky structure and steric hindrance of the POSS units as well as the complexation between N of the monomers and Ru which is present in Grubbs catalyst. Encouraged by the above results, we managed to employ N-methylation of monomer 2 to eliminate catalyst inhibition. The state of the monomer changed from pale yellow sticky liquid to fluffy yellow powder after methylation followed by characterized the ionomer with 1H NMR,13C NMR, FT-IR and Elemental Analysis to confirm the methylation was successfully proceeded. Then, ADMET polymerizations of the above obtained ionmomer were investigated and the molecular weights of the corresponding polymers were characterized with GPC. The results showed that the polymerization degrees of the corresponding polymers increased significantly compared to the polymers based on monomer 2 at the same conditions, which demonstrated that methylation was extraordinary operative to eliminate catalyst inhibition. Polymer which based on monomer 3 was further hydrogenated with p-toluenesulfonhydrazide and the hydrogenation was reasonably performed in high yield with virtually little remaining unsaturation as monitored by 1H NMR spectroscopy. The properties and morphology of the corresponding hydrogenated polymer were characterized with TGA, DSC, XRD and AFM.