以醋酸纤维素(CA)为膜阻隔层,聚羟基丁酸/戊酸酯共聚物(PHBV)作为膜支撑层,利用静电纺丝法制备出复合膜。研究了醋酸纤维素质量分数、溶剂配比、电压,以及CA与PHBV复合比(体积比)对纤维形态及复合膜性能的影响,并通过扫描电镜表征了CA纤维膜的表面形貌。研究结果表明,当CA的质量分数为12%,溶剂丙酮与N,N-二甲基乙酰胺(DMAc)体积比为1/1,纺丝电压为14 k V时,CA纤维膜形态均匀,并呈现独特的双纤维直径交错结构。这种结构的膜材料有利于在提高水通量的同时,保持其较好的截留率。同时,当CA/PHBV的复合比为10/10时,复合膜的水通量能达到104数量级,截留率可以达到87%。
A series of novel polyamides 3a-3d containing 4-tert-butyltoluene moiety, were prepared using the phosphorylation polycondensation technique. FT-IR and 1↑H NMR techniques were used to investigate the chemical structures of 3a-3d. The results confirmed that they agreed with the proposed structures for 3a-3d completely. The 3a-3d had inherent viscosities ranging from 0.71 to 1.67 dL·g^-1. All the polyamides showed excellent solubility, with the dissolvability at a concentration of 10 wt% in most amide polar solvents. Flexible and tough polyamide films could be prepared by casting from DMAc （N,N-dimethylacetamide） solvent. Their films were nearly colorless and exhibited high optical transparency, with the UV cutoff wavelength in the range of 346-363 nm and transmittance higher than 80% at 450 nm. They also exhibited high glass transition temperatures in the range of 310---343℃ and the onset decomposition temperatures in the range of 435-462 ℃ in nitrogen atmosphere. Meanwhile, these polyamide films possess good mechanical properties with tensile strengths of 76.4-86.1 MPa and elongations at break of 11.2%-27.3%. Due to those properties, these polyamides could be considered as photoelectric and microelectronic materials.
Novel poly（thioether imide）s were synthesized by 2,5-dimercapto-l,3,4-thiadiazole, and aromatic heterocyclic chlorodiimids through nucleophilic!substitution reaction as alkali catalysts were presented. The poly（thioether imide）s exhibited good thermal property. The glass transition temperatures of polymers were around 373 ℃, and 10% weight loss temperatures were in the range of 450-500 ℃ in nitrogen/air atmosphere. Meanwhile, the chloroform dilute solutions of these polYmers could show strong UV-vis absorption peaks at about 289 nm. After being protonated by inorganic acids （HC1）, the new shoulder absorption peaks were observed at 350 nm. The PL absorption bands of polymer solutions were in the region of 350-550 nm, which showed the green-yellow fluorescence.
A new unsymmetrical and noncoplanar diamine containing trifluoromethyl and trimethyl groups, 1,4-bis（4- amino-2-trifluoromethylphenoxy）-2,3,5-trimethylbenzene （2）, was synthesized using 2,3,5-trimethylhydroquinone and 2-chloro-5-nitrobenzotrifluoride as starting materials. A series of fluorinated poly（ether imide）s （PEIs） （4a-4d） were prepared from diamine 2 with four aromatic dianhydrides via a one-step high-temperature polycondensation procedure. The obtained PEIs were readily soluble in most organic solvents and could be solution-cast into flexible and strong films. The resulting thin films exhibited light color and good optical transparency with a cutoff wave- length of 356--376 nm. They also displayed good thermal stability with glass transition temperatures （Tg） above 281℃, 10% weight loss temperatures in the range of 482--486 ~C, and the weight residue more than 55% at 800℃ in nitrogen. Moreover, they revealed low dielectric constants （2.77-2.93 at 1 MHz） and low moisture absorp- tions （0.41%-0.57%）.
A new aromatic diamine containing trifluoromethyl and methyl groups, namely a,a-bis（4-amino-3-methylphetayl）-4-（trifluoromethyl）phenylmethane （1）, was synthesized from 2-methylaniline and 4-（trifluoromethyl）- benzaldehyde. A series of fluorinated polyimides （PIs） were prepared from the diamine with four commercially available aromatic tetracarboxylic dianhydrides using a one-step high-temperature polycondensation procedure. These obtained PIs showed excellent solubility, with the dissolvability at a concentration of 10 wt% in most solvents, and they could afford flexible and strong films. Thin films of these PIs exhibited high optical transparency and light color, with the cutoff wavelength at 324-357 nm and transmittance higher than 74% at 450 nm. Moreover, these Pls possessed eminent thermal stability and good mechanical properties.
