藉由氫鍵調控多面體聚矽氧烷自組裝行為與聚苯乙烯/聚丁二烯摻混之微細發泡結構及其機械性質之研究

Abstract

有機無機複合奈米粒子利用粒子表面有機基團和摻混的小分子或寡聚體，其間氫鍵作用力，提供了更多變更廣範的功能性奈米材料，並且有效提升原始材料的光學性、電性以及機械性質。在合適的狀況下，小分子或寡聚體經由分子設計摻混其它種類的小分子可形成某特殊形態結構，展現類似高分子的流變、機械及熱性質的行為。因此運用分子設計，製備具有自組裝特性的奈米級粒子已受到許多的科學研究學者的矚目與探討。 首先，我們合成具有四吡啶基星狀化合物(TNMM)和八酚的多面體聚矽氧烷(OP-POSS)材料，文中我們觀察吡啶與酚基間的氫鍵變化，摻混不同比例得到不同氫鍵比例組成的分子網狀結構，以OP-POSS為計量基準，隨著TNMM的含量增加，酚基與吡啶基間的氫鍵比例跟著增加，不同比例的摻混，其熱性質呈現熱可逆的特性，相較於室溫為黏稠液體的OP-POSS (具低玻璃轉移溫度，Tg=14.4 °C)，摻混40 wt %的TNMM的氫鍵複合網狀結構呈現透明玻璃狀固體，Tg為37 °C。此外，在碳膜稀薄溶液，溶劑揮發過程即除潤(Dewetting)程序，摻混40 wt %的TNMM的氫鍵複合超分子呈現數微米直徑的圓環微結構。 在第二個部分中，我們摻混聚苯乙烯(PS)、苯乙烯-丁二烯橡膠(SRB)及苯乙烯-丁二烯-苯乙烯三段共聚物(SBS)獲得較佳的機械性質及微結構以利微孔發泡形成具緻密封閉性泡孔的多孔性高分子結構體，混入不同比例的交聯劑(架橋劑)、發泡劑、交聯劑、填充劑及助劑等進行密閉高溫發泡以獲得不同孔洞大小以及分佈的發泡材料，發現增加架橋劑可以補強發泡孔洞結構，提升的機械性質包括硬度、收縮性、抗拉伸強度、撕裂强度、斷裂伸長率和壓縮率。

Inorganic nanoparticles (NPs) enclosed within hydrogen bonding between small molecules or oligomers provide new opportunities for the development of functional hybrid materials that exhibit enhanced optical, electrical, and mechanical properties. Under suitable experimental conditions, such assemblies can display polymer-like rheological or mechanical properties, because of their macromolecular architecture. As an alternative to these fabrication pathways, routes that use the self-assembly of nanoparticle are attracting increasing attention. (1) In part one, a pyridine-functionalized pentaerythritol star polyester compound (TNMM) and an octakis[dimethyl(4-hydroxyphenethyl)siloxy]silsesquioxane (OP-POSS) were synthesized and used as tetrahedral and cubic building blocks, respectively, for three-dimensional, hydrogen bond–mediated, POSS-based supramolecular network structures. With noncovalent chain extension of hydrogen bonds between its pyridine and phenol groups, the POSS-based supramolecular networks exhibited thermally reversible properties. Compared with the glass transition temperature of OP-POSS (ca. 14.4 °C) and the melting temperature of TNMM (ca. 160 °C), the hydrogen bond-mediated miscible blend of 40 wt % TNMM in OP-POSS exhibited a single and higher glass transition temperature (37 °C). Because of its strong intermolecular hydrogen bonding, the dewetting pattern of the blend of 40 wt% TNMM in OP-POSS formed ring-like structures, rather than the droplets formed by pure OP-POSS. A transparent, brittle, and glassy solid at room temperature, the blend of 40 wt% TNMM in OP-POSS is an explicit and successful example of a POSS-based hydrogen-bonded supramolecular network. (2) This study investigates the effect of peroxide crosslinking on the structure and mechanical properties for PS/PB foams composed of polystyrene (PS), polystyrene-block-polybutadiene (SBR), and polystyrene-block-polybutadiene-block- polystyrene (SBS). The cell size and its distribution of PS/PB foams was investigated by SEM images, showing the smaller and denser of hollow cells for the PS/PB foam containing the more concentration of DCP (dicumyl peroxide). As expected, the density of the PS/PB foams increases with increasing the content of DCP. The high density of polymeric foams exhibit the high mechanical properties such as hardness, shrinkage, tensile strength, tear strength, elongation at break, and compression set.