本文關(guān)鍵詞：聚合物薄膜表面活性層厚度與其分子量關(guān)系研究　出處：《浙江理工大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 分子運動 深度分布 分子量依賴性 表面層厚度 聚合物薄膜 玻璃化轉(zhuǎn)變

【摘要】：聚合物表面分子動力學(xué)是高分子物理領(lǐng)域的重要理論科學(xué)問題之一。表面高分子鏈具有與本體不同的聚集態(tài)結(jié)構(gòu)及分子運動能力,其重要特征之一在于其具有深度依賴性。隨著距離表面深度的增加,相應(yīng)深度高分子鏈的分子運動行為也隨之發(fā)生變化。近年來,聚合物表面分子運動能力的深度依賴性成為了表面動力學(xué)領(lǐng)域的研究熱點之一。由于研究手段的缺乏,聚合物表面玻璃化轉(zhuǎn)變行為的分子量依賴性的文獻報道相對較少,而且不同方法得到的研究結(jié)果不能很好地統(tǒng)一。弄清表面玻璃化轉(zhuǎn)變溫度、表面效應(yīng)的影響深度與聚合物鏈尺寸(分子量)的關(guān)系,對于進一步澄清聚合物表面分子動力學(xué)的微觀物理機制具有重要意義。為了解決聚合物表面玻璃化轉(zhuǎn)變深度分布及其分子量依賴性的問題,本文采用含氟基團標(biāo)記結(jié)合不同表面深度敏感度的表面表征手段研究了不同分子量的聚甲基丙烯酸甲酯與聚苯乙烯表面分子玻璃化轉(zhuǎn)變行為及其分子量依賴性。并關(guān)聯(lián)了表面Tg的分子量依賴性與其薄膜玻璃化轉(zhuǎn)變行為的關(guān)系,所得結(jié)論如下:(1)聚合物表面分子運動能力呈現(xiàn)出深度依賴性。根據(jù)分子運動能力與深度的關(guān)系可以將聚合物膜劃分為三層。第一層為直接與空氣接觸厚度很薄的表面層(surface layer),該層其分子運動能力很強,Tg不隨深度的改變而變化。第二層為梯度層(gradient region),該區(qū)域內(nèi)的局部Tg隨深度增加而上升,將表面的高活性傳遞至本體。第三層為本體層。(2)PMMA與PS薄膜表面活性層厚度與表面層Tg均依賴于聚合物鏈尺寸(分子量)。表面層厚度與高分子鏈回轉(zhuǎn)半徑大約呈0.45的倍數(shù)關(guān)系:Hsurface=0.45 R這是由于聚合物/空氣界面的存在,表面高分子鏈采取橢球狀的構(gòu)象而造成的;表面Tg與鏈回轉(zhuǎn)半徑的關(guān)系為:Tg PMMA=2.1 Rg+57.6,Tg PS=1.57 Rg+59.4,說明隨著聚合物分子量增大,表面高分子鏈運動能力減弱。表面高分子鏈的“滑移運動”機制可以對這一現(xiàn)象進行定性解釋。本實驗結(jié)果也直接證實了de gennes提出的“滑移運動”理論模型的合理性。(3)利用water casting的方法在二氧化硅基底上構(gòu)筑一層PMMA強吸附層,然后以其為基底制備不同厚度的無界面效應(yīng)的PMMA薄膜,使用成像橢圓偏振儀對薄膜進行Tg的測定,結(jié)果發(fā)現(xiàn)薄膜Tg存在分子量依賴性。且薄膜厚度越小,薄膜Tg受分子量的影響越大。將之前通過不同分析深度的CA、SFG及XPS測得的表面Tg值與橢圓偏振儀測得的薄膜Tg值進行疊加,發(fā)現(xiàn)二者吻合度良好。這是由于當(dāng)薄膜厚度較小時,表面層所占體積分?jǐn)?shù)較大,聚合物表面分子運動能力的分子量依賴性導(dǎo)致薄膜整體Tg依賴于分子量;隨著薄膜厚度的上升,表面層在薄膜中所占體積分?jǐn)?shù)降低,薄膜Tg受分子量的依賴性減弱,最終達到本體Tg值。
[Abstract]:The surface of the polymer molecular dynamics theory is one of the most important scientific problems in polymer physics. The surface of polymer chains with different ontology aggregation structure and molecular mobility, one of its important features is that it has a depth dependence. With the increase of depth from the surface, the corresponding depth of molecular motion behavior of polymer chains has changed in recent years. The molecular mobility of polymer surface, depth dependence has become a hot topic in the field of surface dynamics. Due to the lack of methods, the molecular weight of polymer on the surface of the glass transition behavior of the dependence of the literature is relatively small, and the results obtained by different methods is not well unified. Clarify the surface of the glass transition temperature, influence the depth and size of the surface effect of polymer chains (molecular weight) of the relationship, to further clarify the polymer surface points The micro physical mechanism has important significance. In order to solve the transformation of subdynamics depth distribution of polymer surface glass and its molecular weight dependence of the problem, this paper uses fluorinated groups of PMMA and polystyrene labeled molecule on the surface of glass transition behavior and different molecular weight dependence with different surface depth sensitive surface characterization methods. And the relationship between the molecular weight dependence of the surface of Tg films with glass transition behavior, the conclusions are as follows: (1) the polymer surface molecular movement ability showing depth dependence. According to the relationship between the molecular movement ability and the depth of the polymer film can be divided into three layers. The first layer is in direct contact with the air is very thin the surface layer (surface layer), the layer of the molecular motion ability is very strong, Tg does not change with depth change. The second layer is gradient Layer (gradient region), local Tg in the region increased with increasing depth, high active surface transfer to the body. The third layer is the ontology layer. (2) surface activity of PMMA and PS thin film thickness and surface layer of Tg are dependent on the size of the polymer chain (molecular weight). The thickness of the surface layer and the polymer the chain is about 0.45 times the radius of gyration relationship: Hsurface=0.45 R this is due to the presence of the polymer / air interface, the surface of polymer chain conformation to ellipsoidal caused; relationship between surface Tg and the radius of gyration chain is: Tg PMMA=2.1 Rg+57.6, Tg PS=1.57 Rg+ 59.4, with the molecular weight of the polymer increases, weaken the surface of polymer chain exercise capacity. Surface of polymer chain "slip" mechanism of this phenomenon is explained. The experimental results also confirmed that de Gennes's "slip" theory model. The rationality of the use of W (3) Ater casting PMMA is a layer of strong adsorption layer on the silica substrate, and the interface effect of PMMA thin film substrates with different thickness, determination of Tg on film using imaging ellipsometry, results showed that the molecular weight dependence of Tg thin film. And the film thickness is small and the effect of film Tg the molecular weight of the larger. Through different depth analysis of CA SFG and XPS before the measurement of surface Tg values of Tg films with ellipsometry measured values were superimposed, it is found that the two good agreement. This is because when the film thickness is small, the surface layer of volume fraction of large molecular weight. The polymer surface molecular mobility dependence leads to the whole film Tg depends on the molecular weight; with the rise of film thickness, surface layer volume fraction decreased, dependent on the molecular weight of Tg films decreased, and eventually reach the body Tg value.

【學(xué)位授予單位】：浙江理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TB383.2;TQ317

【參考文獻】

相關(guān)期刊論文 前4條

1 李鯤,郭建華,李欣欣,吳平平,韓哲文;原子轉(zhuǎn)移自由基聚合合成甲基丙烯酸丁酯與丙烯酸全氟烷基乙酯兩嵌段共聚物及其性能的研究[J];高分子學(xué)報;2002年02期

2 Dong-dong Peng;Ran-xing Nancy Li;Chi-hang Lam;Ophelia K.C.Tsui;;TWO-LAYER MODEL DESCRIPTION OF POLYMER THIN FILM DYNAMICS[J];Chinese Journal of Polymer Science;2013年01期

3 劉望龍;左彪;楊燕航;丁佳;王新平;沈之荃;;基底界面效應(yīng)對聚苯乙烯薄膜分子運動行為的影響[J];中國科學(xué):化學(xué);2013年10期

4 劉英軍;朱玉梅;王宇;李雪華;左彪;楊菊萍;王新平;姚炎慶;沈之荃;;聚苯乙烯分子鏈構(gòu)象與其薄膜的玻璃化轉(zhuǎn)變行為[J];中國科學(xué):化學(xué);2014年12期

，

本文編號：1377964