| The present thesis was aimed on the synthesis of linear/hyperbranched poly(urethane-benzyltetrazole), hyperbranched poly(urethane-tetrazole) and benzyltetrazole-containing triethoxysilane. The different types of crosslinked membranes were obtained via sol-gel process, thermal and/or UV curing process. The hydrogen bond density in the cured membranes was enhanced by introducing the tetrazole group, resulting in the unique properties of cured membranes. The studies mainly focused on the synthesis of polymers containing tetrazole group, the proton conducting behavior of their organic/inorganic hybrid membranes, as well, the shape memory behavior prepared from hyperbranched poly(urethane-tetrazole) via"A2+BB'2"approach.1. Synthesis and characterization of linear/hyperbranched poly(urethane-benzyltetrazole)A series of poly(urethane-benzyltetrazoles) (PBTZs) with different linkage structures were synthesized via the addition polymerization of hexadiisocyanate (HDI) as an A2 type monomer with (4-(1H-tetrazol-5-yl)benzyl)-diethanolamine (TBDEA) as a BB'2 type monomer under different reaction conditions, such as catalyst and temperature, including linear poly(urethane-benzylretrazole) (LPBTZ) and hyperbranched poly(urethane-benzylretrazoles) (HPBTZs). The FTIR, and 13C and 1H NMR spectroscopy were used to characterize the molecular structures of TBDEA, LPBTZ and HPBTZ. The molecular topologic structure was determined by the reaction selectivity that the isocyanate group reacted with the hydroxyl group in diethanolamine segment or the active hydrogen atom on tetrazole ring. The results showed that the existence of DBTDL as a catalyst was helpful to improve the reaction activity between hydroxyl group in diethanolamine segment and isocyanate group. Hence, at 30°C with BDTDL addition, LPBTZ with side benzyltetrazole groups was obtained. Its number-average molecule weight was measured to be 5,986 g/mol with a wider molecular weight distribution of 3.84 by GPC. Raising reaction temperature was propitious to the reaction of isocyanate group with the active hydrogen atom on tetrazole ring. It was found that at the reaction temperatures, 30°C, 60°C and 80°C, without DBTDL addition, the HPBTZs were prepared. The degrees of branching (DB) for HPBTZs obtained from the 1H NMR spectra increased with reaction temperature raised. At 30°C, 60°C and 80°C for 24 h, the corresponding DB value was 0.29, 0.43 and 0.48. The wider molecular weight distribution of 1.7-2.9 for HPBTZs was obtained via GPC analysis. TGA results showed that HPBTZs have high thermal stability compared with LPBTZ.2. Preparation and conducting behavior of amphibious organic/inorganic hybrid proton exchange membranes based on poly(urethane-benzyltetrazole) with acid doping by sol-gel approachA series of precursors with H3PO4 doping were prepared through a sol-gel process based on acrylated triethoxysilane (A-TES) and benzyltetrazole-modified triethoxysilane (BT-TES). The novel amphibious organic/inorganic hybrid proton exchange membranes which could be used under both wet and dry conditions were prepared through the UV-curing and thermal curing of the precursors blending with polyethylene glycol (400) diacrylate. The molecular structures of A-TES and BT-TES were characterized by 1H, 13C and 29Si NMR spectra. The TGA results showed that the membranes behaved acceptable thermal stability for their applications above 200℃. The DSC determination indicated that the crosslinked membranes with the weight rations of below 1.6 for BT-TES to A-TES and the same weight H3PO4 doping as A-TES possess the minus Tgs, as well the lowest Tg (-28.9℃) for that with double weight H3PO4 doping and the ratio of BT-TES to A-TES reaching to 2.4. The high proton conductivity in the range of 9.4-17.3 mS cm-1 with the corresponding water uptake of 19.1-32.8 % of the membranes was detected at 90℃in wet condition. Moreover,, the excellent proton conducting performance of hybrids was obtained in dry condition, and further improved with increasing temperature. The proton conductivity under dry environment for the membrane with the weight ratio of 2.4 for BT-TES to A-TES and double H3PO4 loading increased from 4.89×10-2 mS cm-1 at 30℃to 25.7 mS cm-1 at 140℃. The excellent proton transport ability under both hydrous and anhydrous conditions demonstrates a potential application in polymer electrolyte membrane fuel cells.3. Preparation and proton conductivity of organic/inorganic hybrid membrane based on acid-doped linear poly(urethane-benzyltetrazole)The linear poly(urethane-benzyltetrazole) (LPBTZ) with side benzyltetrazole groups was synthesized via the addition polymerization of (4-(1H-tetrazol-5-yl)benzyl)-diethanolamine (TBDEA) with hexadiisocyanate (HDI). The 3-isocyanatopropyl triethoxysilane (IPTS)-endcapped poly(urethane-benzyltetrazole) (PUBTZ) was obtained by the reaction of IPTS with LPBTZ. The addition product (PEO-IPTS) of IPTS with hydrophilic polyethylene oxide (PEO) was prepared as an inorganic component to form the hybrid composite. The benzyltetrazole group was introduced as a proton donor and acceptor at high temperature under dry condition. The number-average molecular weight of LPBTZ was measured by GPC to be 1.13×104 g mol-1 with its polydispersity of 1.83 after polycondensation for 24 h. A series of hybrid proton conductive membranes were prepared by mixing PUBTZ with PEO-IPTS and doping phosphoric acid at various molar ratios, following by a sol-gel process (PUBTZ-Pn, n is the molecule weight of PEO). The thermal property study by DSC indicates that the Tg of PUBTZ-P200 decreased to -11.9℃from 9.2℃, as the molar ratio of PEO-IPTS to PUBTZ increased from 4.67 to 14. Moreover, a lower Tg (-3.8℃) was obtained from PUBTZ-P600 when PEO600 was used. Doping 3.22 mmol phosphoric acid resulted in the decrease of Tg from 9.2℃of 1.61 mmol acid doping to -45.7℃. The proton conductivity of all membranes exceeded 10-3 at testing temperature in 100 % RH. Moreover, their anhydrous proton conductivity were improved as the temperature raised. For PUBTZ-P200F, the anhydrous proton conductivity reached to 2.66 mS cm-1 at 90℃.4. Synthesis and shape memory behavior study of hyperbranched poly(urethane-tetrazole)A novel hyperbranched poly(urethane-tetrazole) (HPUTZ) was synthesized via the"A2+BB'2"approach using hexadiisocyanate (HDI) and 3-(bis-(2-hydroxyethyl)) aminopropyltetrazole (HAPTZ). The molecular structure was characterized by FTIR and 1H NMR spectroscopy. The number average molecular weight was measured to be 1.05×104 g/mol with a polydispersity of 1.27 by GPC analysis. The HPUTZ was further cured by the semi-adduct (PEG-IPDI) from polyethylene glycol (PEG) reacting with isophorone diisocyanate (IPDI) to form the crosslinked HAPTZ-PU films in different ratios of HAPTZ to PEG-IPDI. The glass transition temperature of HAPTZ-PU increased from 44.9℃to 56.4℃as the HPUTZ content increased from 20 % to 33 % from the DSC analysis. The DMA results indicated that the HPUTZ-PU with 20 % HPUTZ possessed the highest storage modulus and loss tangent. However, the storage modulus increased with the increase of HPUTZ segment at higher temperature. The shape memory study showed that all the films presented the excellent shape memory function. Over 98% shape recover could be obtained for the HAPTZ-PU with 20-33 % HAPTZ segment content within 60 s in the tension deformation test and within 40 s at 80℃in the bend deformation test.
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