【作者】 林博；

【导师】 张红东；

【作者基本信息】 复旦大学 ， 高分子化学与物理， 2011， 博士

【摘要】 本论文的工作主要围绕ABC树枝状嵌段共聚物本体相形态、ABC星型三嵌段共聚物薄膜相形态的自洽场理论研究以及线型ABC三嵌段共聚物的RAFT合成展开。第一部分：运用SCFT的实空间解法求来研究树枝状ABC共聚物(dendrimer)在2D空间的相行为。比较了线型、星型、树枝状嵌段共聚物体系在相分离行为上的主要区别,得到七种不同的有序相结构。它们分别是(1)中心对称的12,6,4边形相dodecagon-hexagon-tetragon(DOHT. [12.6.4])；(2)三色层状相"three-color" lamellae phase(LAM3)；(3)核—壳型六角晶格相,core-shell hexagonal lattice phase(CSH)；(4)三色蜂窝六角相,"thrree-color" hexagonal honeycomb phase(HEX3)；(5)结合10,6,4边形和10,6,6边形的中心不对称相结构decagon-hexagon-tetragon, decagon-hexagon-hexagon phase (DEHT;DEHH, [10.6.4;10.6.6])；(6)交替珠子层状相lamellae phase with alternating beads(LAM+BD);(7)8,8,4多边形相octagon-octagon-tetragon phase (00T,[8.8.4]).通过系统改变树枝状共聚物第一代共聚物的组成,得到对称相互作用(xABN =xACN=XBCN=80)和不对称相互作用(xABN=80,xACN=xBCN=100)的三张三元相图。树枝状共聚物有4个三链段的汇结点,这种高分子链的拓扑结构约束使其相结构变得更加复杂。尤其是当三组分的组成差别不大(fA≈fB≈fC)时,在三角形相图的中心区域可以搜索到完美的三色蜂窝六角相HEX3微相结构。此外在三角形相图靠近HEX3区域的位置,还出现了与HEX3能量接近、体系相形态互相竞争的8,8,4边形的微相结构(OOT)。我们还在树枝状共聚物的相图中明确了中心对称的12,6,4多边形(DOHT)相形态的出现,同时也补充说明了10,6,4边形不是体系单一的相区,它往往伴随另外一种10,6,6边形相区的出现,进而形成整个中心不对称的微相结构([10.6.4；10.6.6])。然而,当体系的一个组分的组成很大(fA(orfB,fc)≥0.7)时,而其他的两个组分的组成很小,则树枝状共聚物的特征得不到充分的表现,这时候的相行为(LAM3 or LAM+BD)类似于线型三嵌段共聚物。第二部分：嵌段共聚物薄膜是一种普遍而且重要的受限体系。受限体系的边界效应在给嵌段的熵带来变化的同时,受限边界对不同嵌段的浸润性质也会引起也会引起表面能的变化,两者的共同作用可以很大程度地改变受限边界附近的嵌段的分子构型,从而改变受限表面附近区域的微相分离形态。这一部分运用自洽场理论结合伪谱算法系统地模拟了在两个性质相同的平行基板之间的受限星型A0.3B0.3C0.4三嵌段共聚物薄膜的相行为。在模拟中,选择体系各个链段组分的体积分数近似相等(fA=fB=0.3,fB=0.4)以突出线型聚合物的高分子链段的特征结构。在三个不同的系列的组分间相互作用下,着重考察了嵌段共聚物薄膜厚度,表面场的强度对共聚物薄膜相行为的影响。研究结果表明,在受限及表面场的作用下出现了一系列稳定的相形态,包括柱状相、层状相、穿孔层状相以及混合结构相；在我们的模拟过程中,那些以星型三嵌段共聚物中的其中一个嵌段形成类似无机CsCl结构的混合结构相形态尤其引起我们的兴趣。结果表明,这样的混合结构相形态常常会出现在一个较大的混合结构区域(H-区域),这是由于它们的自由能太过接近以致于难以被区分开来的缘故；通过系统性的调节星型三嵌段共聚物薄膜的厚度和表面场的强度,来确定和评价嵌段共聚物的相行为及相转变；同时我们对比了弱选择性平面场与强选择性表面场的相图,最后讨论了聚合物薄膜厚度、表面场的选择性以及星型三嵌段共聚物的本身性质对不同厚度的的星型三嵌段共聚物薄膜的稳定性的影响。第三部分：以偶氮二异丁腈为引发剂,二硫代苯甲酸异丙苯酯以链转移剂的RAFT活性聚合技术合成了两种不同的线型三嵌段共聚物：等臂的聚(甲基丙烯酸特丁酯)-b-聚(甲基丙烯酸环氧丙酯)-b-聚(苯乙烯)和接近等臂的聚(甲基丙烯酸特丁酯)-b-聚(甲基丙烯酸羟乙酯)-b-聚(N,N-二甲基乙基甲基丙烯酸甲酯)。红外光谱说明了这些线型三嵌段共聚物的嵌段特征官能团的分子结构与’H核磁共振图谱的测试结果一致。通过’H核磁共振图谱还确定了线型三嵌段共聚物各个嵌段的聚合度。此外,还采用两种不同的非等温热分解动力学分析方法：Friedma微分法和Ozawa-Flymn-Wall积分法,来补充说明它们各自的热稳定性。分析结果表明：聚(甲基丙烯酸特丁酯)-b-聚(甲基丙烯酸环氧丙酯)-b-聚(苯乙烯)的热分解活化能远大于聚(甲基丙烯酸特丁酯)-b-聚(甲基丙烯酸羟乙酯)-b-聚(N,N-二甲基乙基甲基丙烯酸甲酯),是由于前者在聚合过程中引入了刚性的苯环官能团以及带有反应活性的环氧基团嵌段。更多还原

【Abstract】 In this thesis, the study mainly includes the following three aspects:(ⅰ) self-assembly of ABC dendrimer by real-space self-consistent mean field theory; (ⅱ) self-assembly of ABC star triblock copolymer thin films confined with a preferential surface:a self-consistent mean field theory; (ⅲ) synthesis and thermal analysis of linear triblock copolymers based on methacrylate ester.In the first part, we systematically studied the phase behavior of ABC dendrimer melt systems by real-space implementation of self-consistent mean field theory, and compared it with linear, star ABC triblock copolymer to find the major influences of different chain topology. Seven ordered morphologies have been observed during the simulation. They are (a) dodecagon-hexagon-tetragon (DOHT. [12.6.4]); (b) "three-color" lamellae phase (LAM3); (c) core-shell hexagonal lattice phase (CSH); (d) "three-color" hexagonal honeycomb phase (HEX3); (e) decagon-hexagon-tetragon, decagon-hexagon-hexagon phase (DEHT, DEHH. [10.6.4; 10.6.6]); (f) lamellae phase with alternating beads (LAM+BD); (g) octagon-octagon-tetragon phase (OOT. [8.8.4]). Most of them present in the simulation of linear or star ABC triblock copolymer; however, the DOHT is particular in ABC dendrimer.Triangle phase diagrams are constructed for three classes of typical ABC dendrimer in terms of the relative strength of the interaction parameters:symmetric interaction parameters xABN=xACN=xBCN=80 and asymmetric interaction parameters one, xABN=80, xACN= XBCN=100. When the volume fraction and interaction energies of the three species are comparable, the HEX3 phase is found to be the most stable. Near the region of HEX3 in the triangle phase diagrams, we found another competitive microphase (OOT) with its energy is close to HEX3. The DOHT phase is first reported in the ABC dendrimer, and the decagon-hexagon-tetragon, decagon-hexagon-hexagon phase ([10.6.4; 10.6.6]) mixed phase is complementary shown as a microphase with asymmetric center. When the volume of one species is big enough, such as fA(or fB,fc)≥0.7, the chain topology of dendrimer do not stretch as it want to be, then it takes a LAM+BD microphase as linear ABC triblock copolymers.In the second part, microphase separation and morphology of a near-symmetric A0.3B0.3C0.4 star triblock copolymer thin film confined between two parallel and homogeneous hard walls have been investigated by self-consistent mean field theory (SCMFT) with a pseudo-spectral method. Our simulation experiments reveal that under surface confinement, in addition to the typically parallel, perpendicular, and tilted cylinders, other phases, such as lamellae, perforated lamellae, and complex hybrid phases, have been found to be stable, which are attributed to the block-substrate interactions. Especially those hybrid phases in which A block and B block disperse as spheres and alternately arrange as cubic CsCl structures, with a network perforative structure of C block. The results show that these hybrid phases are also stable within a broad hybrid region (H-region) under suitable film thickness and broad field strength of substrates, due to their free energies is too close to being distinguished. Phase diagrams have been evaluated by purposefully and systematically varying the film thickness and field strength at three different cases of Flory-Huggins interaction parameters between species in the star polymer. We also compare the phase diagrams for weak and strong preferential substrates, each with a couple of opposite quality and discuss the influence of confinement, substrate preference, and the nature of the star polymer on the stability of relatively thinner and thick film phases in this work.In the third part, Two linear triblock copolymer:poly(t-butyl methacrylate-b-glycidyl methacrylate-b-styrene) with equivalent arms (PtBMA97-b-PGMA18-b-PSt98), and poly(t-butyl methacrylate-b-2-hydroxyl ethyl methacrylate-b-N,N-dimethylamino-ethyl methacrylate) with unequal arms (PtBMA137-b-PHEMA23-b-PDMAEMA156) were controlled synthesized with living RAFT polymerization technique under the chain transfer of cumyl dithiobenzoate. The results of FT-IR spectra illuminates that the characteristic groups of copolymer fit well with the result of 1H-NMR which successfully determine the corresponding molecular structure of triblock copolymers. The thermal stability of PtBMA97-b-PGMA18-b-PSt98 and PtBMA137-b-PHEMA23-b-PDMAEMA156 were also complementarily explained by the activation energy of thermal decomposition from Friedman differential method and Ozawa-Flynn-Wall integral method. The results show that the degradation energy of the former copolymer was much higher than that of the latter copolymer due to the aromatic groups were introduced into the polymer segments of the former copolymer during the RAFT polymerization process and because of the oxirane rings are typically reactive, that they occurred intermolecular crosslinking reaction during the thermal decomposition.更多还原