【作者】 魏玉萍；

【导师】 于九皋； 程发；

【作者基本信息】 天津大学 ， 应用化学， 2005， 博士

【摘要】 纤维素是地球上最为丰富的可再生资源,利用纤维素为原料开发一种无毒、无污染的环境友好的高分子表面活性剂,不仅可以解决当前石油工业的能源危机,而且可以为纤维素的合理利用开辟新的途径,同时得到的表面活性剂有望生物降解,因此具有重大的现实意义。本文以聚合度为280的纤维素为原料,溶液化后,与长链脂肪酰氯进行酯化反应,对纤维素主链引入疏水链段,得到的纤维素长链脂肪酸酯再进行硫酸酯化,以引入亲水链段,创造性地制备了一种新型结构的纤维素类高分子表面活性剂,并将纤维素的新溶剂体系LiCl/DMAc引入到高分子表面活性剂的合成当中,同时还测定了该表面活性剂临界聚集浓度下的表面张力、胶束形态与尺寸,主要内容及结论如下:1.选用聚合度分别为280、643、850三种纤维素为研究对象,经去离子水、甲醇、DMAc溶剂交换后,溶于LiCl/DMAc中,利用高级流变仪对三种纤维素LiCl/DMAc溶液的流变行为进行了研究,动态流变实验结果表明,在实验选择的频率范围,纤维素的LiCl/DMAc溶液体系基本呈粘弹体行为,即G′随频率的增加而增加, G″起初也增加,到G′变化最快的频率时, G″达到最大值;力学内耗tanδ随着频率的增大而降低直至趋于0;从G′与G″交点处的储量G_c ,可以推断出三种不同聚合度纤维素分子量的分散性次序:2#>3#>4#;纤维素溶液温度由50℃升高到80℃时,由于分子运动加快,储能模量G′和耗能模量G″交点处的储量G_c值较低,且频率也相应地降低, tanδ有不同程度地增大。这些研究结果为纤维素LiCl/DMAc溶液的实际应用提供理论基础。2.以辛酰氯为酰化试剂,三乙胺为缚酸剂,在纤维素的LiCl/DMAc均相溶液中,制备了DS=0.43的纤维素辛酰酯,FT-IR、元素分析、CP/MAS ¹³C-NMR、X-ray及SEM等测试手段对其结构及性质进行了表征;得到的DS=0.43的纤维素辛酰酯作为原料,HClSO₃/DMF为硫酸化试剂,45℃左右,5.5h制备了纤维素辛酰酯硫酸钠,FT-IR和¹³C-NMR的测试结果表明,纤维素辛酰酯硫酸钠（ESC）这种新型结构高分子表面活性剂的成功合成,ICP分析结果表明,硫酸钠的取代度可达0.543,基本可以满足表面活性剂的亲水性要求。本研究打破了传统纤维素类高分子表面活性剂先亲水后疏水改性的合成方法,并将纤维素的LiCl/DMAc溶剂体系引入到高分子表面活性剂的合成当中,成功地合成了纤维素辛酰酯硫酸钠这种结构新型的纤维素类高分子表面活性剂,为纤更多还原

【Abstract】 Cellulose is one of the most abundant, naturally occurring polymers usedcommercially. In this paper, a new kind of cellulose-based polymeric surfactant wasdeveloped and synthesized. The potential of this project seems to be great in the viewof either the efficient use of energy and raw material, or the environmental protect.A kind of cellulose with DP=280 was employed as raw materials. After solventexchanged, cellulose was dissolved in LiCl/DMAc, then reacted with octanoylchloride to produce cellulose octanoate in homogeneous solution. The celluloseoctanoate obtained was sulfated with HClSO₃/DMF, after neutralizing with NaOH,the cellulose polymeric surfactant was obtained. And the surface tension, micellesconformation and size of polymeric surfactants were also investigated. This projectchanged the conventional synthesis pathway of cellulose-based polymeric surfactants,and the LiCl/DMAc solvent system was employed in the process of polymericsurfactant synthesis.The overall results as following:Three types of cellulose with different DPs （280, 643, 850） were used as raw material,after solvent-exchanged, dissolved in LiCl/DMAc. Rheological measurements wereused to characterize the behavior of cellulose solution. Results showed that in therange of experimental frequency, three cellulose solutions all showed viscoelasticbehavior. An important characteristic of cellulose solutions is the crossover point forG′ and G″ . At strain rates lower than the crossover strain rate, the G′ values are lessthan G″ , indicating the viscous response dominates. Above the crossover strain rate,the G′ values are greater than G″ . And with the increase of ω , tan δ decreased.From the G_c at the crossover point, the order of polydispersity of three cellulose canbe concluded as following: 2#>3#>4#. The temperature of cellulose solutionincreased from 50℃ to 80℃, the G_c values of decreased, but tan δincreased.Cellulose octanoate with DS=0.43 was synthesized in homogeneous solution usingLiCl/DMAc as solvent and TEA as acid-scavenger. The concentration of cellulosesolution was 2.5wt% with DP of 280. By the CP/MAS ¹³C-NMR、FT-IR、X-ray、SEM、elemental analysis measurements,the cellulose octanoate was characterized. And thecellulose octanoate （DS=0.43） obtained was employed as raw material for furtherhydrophilization. By sulfating with HClSO₃/DMF, then neutralized, a new type ofcellulose polymeric surfactant-cellulose octanoate sulfate was developed andsynthesized. By the FT-IR、13C-NMR measurements and ICP, the cellulose octanoatesulfate obtained was characterized with degree of sulfation as 0.543.By the measuring the surface tension of ESC,the critical congregate concentrationwas obtained as 0.04-0.2wt% and the corresponding surface tension was about 55mN/m. But critical congregate concentration of cellulose sulfate cannot be found in theplot of relationship between the concentration and surface tension. Results showed thatthe surface activity of ESC was superior to cellulose sulfate. In this paper, micellesconformation of polymeric surfactants ESC in aqueous solution was systemicallyinvestigated by dynamic scattering and environmental scanning electron microscopymeasurements. Results showed that polymeric surfactant could also form micellessimilar to conventional ones. When the concentration of ESC was low,the micelleswere spheroidal or ellipsoidal mono-molecule micelles. And at the low concentration,the normalized first-order autocorrelation function （ ）g（t ）1 of ESC can not berepresented by single-exponential decays. At the higher concentration the micelles inaqueous solution would aggregate and form network structure further, but thenormalized first-order autocorrelation function （ ）g（t ）1 of ESC represented bysingle-exponential decays. With the increasing of ESC concentration, the lower sizeregion remained from 50nm to 170nm. The results of rheology test of ESC in aqueoussolution showed that the surfactant had polymeric rheology.更多还原