Polymer-nanoparticle interfacial interactions in polymer nanocomposites: Confinement effects on glass transition temperature and suppression of physical aging
Polymer-nanoparticle interfacial interactions in polymer nanocomposites: Confinement effects on glass transition temperature and suppression of physical aging
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DOI：
10.1002/polb.20925
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发表时间：
2006-10-15
影响因子：
--
通讯作者：
Torkelson, John M.
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文献类型：
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作者：
Rittigstein, Perla;Torkelson, John M.
研究了聚苯乙烯（PS）、聚甲基丙烯酸甲酯（PMMA）和聚2-乙烯基吡啶（P2VP）纳米复合材料的玻璃化转变温度（T-g）和物理老化的影响，这些复合材料含有直径为10 ~ 15纳米的二氧化硅纳米球或直径为47纳米的氧化铝纳米球。纳米复合材料是由聚合物、纳米填料和染料的超声溶液制成的自旋涂层。T(g)s和物理老化率是通过荧光测量的痕量染料水平的薄膜。在0.1-10体积%的纳米填料中，T-g值可以相对于纯、散装T-g （T-g,T-bulk）增强或降低，也可以与纳米填料含量保持不变。对于氧化铝纳米复合材料，T-g相对于T-g增加，在P2VP中t -体积增加多达16 K，在PMMA中t -体积减少多达5 K，而在PS中t -体积不变。通过与聚合物薄膜的类比，这些结果分别可以用具有吸引相互作用的P2VP-纳米填料界面、非润湿PMMA-纳米填料界面（界面处的自由空间）和缺乏吸引相互作用的润湿PS-纳米填料界面来解释。湿界面或非湿界面的存在是通过选择溶剂来控制的。例如，0.1% -0.6体积%的二氧化硅/PMMA纳米复合材料相对于甲基乙基酮或醋酸溶液制备薄膜，其T-g增强幅度可达5k， T-g降低幅度可达17k。在4vol %氧化铝/P2VP纳米复合材料中，物理老化率比纯体P2VP降低了17倍。这表明，要实现稳定或接近稳定的非平衡、玻璃状聚合物体系，一种策略是在聚合物中加入分散良好的纳米颗粒，这些纳米颗粒具有吸引的界面相互作用。(c) 2006 Wiley期刊公司
The effects of confinement on glass transition temperature (T-g) and physical aging are measured in polystyrene (PS), poly(methyl methacrylate) (PMMA), and poly(2-vinyl pyridine) (P2VP) nanocomposites containing 10- to 15-nm-diameter silica nanospheres or 47-nm-diameter alumina nanospheres. Nanocomposites are made by spin coating films from sonicated solutions of polymer, nanofiller, and dye. The T(g)s and physical aging rates are measured by fluorescence of trace levels of dye in the films. At 0.1-10 vol % nanofiller, T-g values can be enhanced or depressed relative to neat, bulk T-g (T-g,T-bulk) or invariant with nanofiller content. For alumina nanocomposites, T-g increases relative to T-g,T-bulk by as much as 16 K in P2VP, decreases by as much as 5 K in PMMA, and is invariant in PS. By analogy with thin polymer films, these results are explained by wetted P2VP-nanofiller interfaces with attractive interactions, nonwetted PMMA-nanofiller interfaces (free space at the interface), and wetted PS-nanofiller interfaces lacking attractive interactions, respectively. The presence of wetted or nonwetted interfaces is controlled by choice of solvent. For example, 0.1-0.6 vol % silica/PMMA nanocomposites exhibit T-g enhancements as large as 5 K or T-g reductions as large as 17 K relative to T-g,T-bulk when films are made from methyl ethyl ketone or acetic acid solutions, respectively. A factor of 17 reduction of physical aging rate relative to that of neat, bulk P2VP is demonstrated in a 4 vol % alumina/P2VP nanocomposite. This suggests that a strategy for achieving nonequilibrium, glassy polymeric systems that are stable or nearly stable to physical aging is to incorporate well-dispersed nanoparticles possessing attractive interfacial interactions with the polymer. (c) 2006 Wiley Periodicals, Inc.