Aladdin), tris(2-aminoethyl)amine (Alfa Aesar), exo-3,6-epoxy-1,2,3,6-tetrahydroxyphthalic anhydride1 (Alfa Aesar), 6-hexamethylene diisocyanate (HDI, Sigma-Aldrich) were used without further purification. Dihydroxyl terminated poly(tetramethylene oxide) glycol (PTMEG-diol) (M n = 2900 g/mol, Reagent grade) was purchased from Aldrich Co., and p-dioxanone (PDO) was provided by the pilot plant of the center for degradable and flame-retardant polymeric materials (Chengdu, China), and dried over C

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... H 2 for 48 h, then diatilled under a reduced pressure of 70 Pa just before used. N,N-dimethylformamide (DMF) was used was dried over 4 A molecular sieve for 72 h, distilled under reduced pressure of 70 Pa just before use. CHCl 3 was washed three times by distilled water,dried by refluxing over P 2 O 5 and distilled just before use. 1, 1, 1, 3, 3, 3-Hexafluoroisopropanol, pentane and methanol were used without further purification. Tris(2-maleimide ethyl)amine were synthesized as previously reported. Analytical Methods Fourier transform infrared (FTIR) spectra of the samples were recorded on a Fourier transform infrared spectrometer in a range of wave numbers from 4000 to 700cm -1 . The resolution and scanning time were 4 cm -1 and 32 times, respectively. The samples were milled into powders and then mixed and laminated with KBr. The chemical structures and number-average number (M n ) of the obtained samples were characterized at 400 MHz using Bruker AV400 spectrometer in CDCl 3 , with tetramethylsilane as the internal standard. The molecular weights were obtained at 35 ℃ by gel permeation chromatography (GPC), using a Waters GPC device equipped with a 1515 pump, a Waters model 717 autosampler, and a 2414 refractive index detector. Chloroform was employed as the eluent at a flow rate of 1.0 mL min -1 , and a sample concentration of 2.5 mg mL -1 was used. The UV-vis spectra were measured by a VARIAN CARY-50 spectrophotometer. The films were prepared by casting the PPDO-PTMEG solution onto quartz substrates. Swelling and gel content were measured by immersing the samples in chloroform at room temperature, and then dried them in vacuum until constant weight. The percentages were obtained by the following equations: