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大四寫論文

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Results and discussion
Polymer synthesis
Optically active aromatic PA5a–PA5h containing bulky pendent group were synthesized from the reaction of optically active dicarboxylic diacid 1 with aromatic diamines 2a–2h by the direct polycondensation procedure using two different methods (Scheme 1).
From a technological viewpoint, the use of an organic solvent in large-scale production is not very affable. So we carried out the polymerization reaction in imidazolium types ILs in order to description a safe, straightforward and efficient method for polymerization reaction. At first, in order to choose the best IL for the preparation of PAs, the reaction of monomer 1 with 2h was carried out in different synthetic ILs such as: 1,3-dipropylimidazolium bromide, 1,3-diisopropylimidazolium bromide, 1,3dibenzylimidazolium chloride, 1,3-dibenzylimidazolium bromide, 1,3-dibutylimidazolium bromide, 1,3-dipentylimidazolium bromide, 1,3- diheptylimidazolium bromide, 1,3-dialylimidazolium chloride and 1,3-dialylimidazolium bromide and in the absence of any IL under oil bath (Scheme 2) and the results are shown in Table 1. According to Table 1 the best inherent viscosity and
yield was obtained when [1,3-(isopr)2im]Br was used as IL for direct polycondensation. So [1,3-(isopr)2im]Br was selected for other polymerization. It is interesting to mention that, the polymers were not obtained in the absence of either of ILs or TPP, so the presence of both components are necessary for polyamidation reactions, and consequently ILs play as a catalyst as well as solvent for these reactions. Since the amounts of ILs were used for each reaction is very low, we did not recycle them. Otherwise, these ILs could be easily separate from resulting polymers and reused
Thus, an efficient, simplified and benign procedure for the preparation of PAs was carried out via direct polyamidation reaction of chiral diacid 1 with different aromatic diamines 2a–2h.
The polymerization reaction was performed using oil bath heating by TPP and 1,3-(isopr)2im]Br as a condensing agent (Method I) and also was carried out under same conditions via Yamazaki phosphorylation reaction, using TPP/Py/NMP/CaCl2 as a condensing agent (Method II) and the results are shown in Tables 2 and 3.

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大四寫論文: 金幣+50, 翻譯EPI+1, ★★★很有幫助 2015-04-09 00:03:33

結(jié)果與討論
聚合物的合成
用兩種不同的方法（圖1）經(jīng)過直接的過程由光學(xué)活性的二羧基的二酸1與芳族二胺2a-2h的反應(yīng)合成了帶有大側(cè)基的光學(xué)活性的芳族PA5a-PA5h。
從技術(shù)觀點來看在大規(guī)模生產(chǎn)中使用有機(jī)溶劑不是很友善的。所以我們在咪唑鹽型IL中進(jìn)行的這種聚合反應(yīng)以說明一個安全、簡單并有效的方法用于聚合反應(yīng)。首先,為了選擇最好的IL用于制備PA,單體1與2h的反應(yīng)是在不同的合成的IL中進(jìn)行的：1,3 -二丙基咪唑溴、1,3 -二異丙基咪唑溴、1,3 -二芐基咪唑氯、1,3 - 二芐基咪唑溴、1,3 -二丁基咪唑溴、1,3 -二苯基咪唑溴1,3 -二庚基咪唑溴、1,3 -二烯丙基咪唑氯和1,3 -二烯丙基咪唑溴，在沒有任何IL的情況下，油浴加熱（圖２），結(jié)果列于表1。根據(jù)表1，當(dāng)使用[ 1,3 - ( isopr) 2im] Br作為用于直接縮聚反應(yīng)的IL時得到最好的特性粘度和收率。所以選擇[ 1,3 - isopr) 2im] Br用于另外的聚合反應(yīng)。令人感興趣的是提到這種聚合物不是在既沒有IL也沒有TPP的情況下得到的,所以兩種成分的存在對聚酰胺化反應(yīng)是必需的,因此IL擔(dān)當(dāng)了這些反應(yīng)的催化劑和溶劑。因為用于各反應(yīng)的IL量非常低,所以我們不進(jìn)行回收。不然,這些IL也很容易從生成的聚合物中分離出并再次使用
因此,通過手性二酸1與不同的芳族二胺2a-2h的直接的聚酰胺化反應(yīng)進(jìn)行了一種有效的、簡化的并溫和的方法用于PA的制備。
用油浴加熱通過TPP和1,3 - ( isopr) 2im] Br作為冷凝劑（方法I）并且還進(jìn)行了相同條件下通過山崎磷�；磻�(yīng),使用TPP/Py/NMP/CaCl2作冷凝劑（方法II）完成了這種聚合反應(yīng)，結(jié)果列于表2和表3。

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2樓2015-04-08 10:50:28