SANS模拟纳米SiO_2-乳胶复合材料退火过程中的中间结构和链构象
Modeling of Intermediate Structures and Chain Conformation in Silica-Latex Nanocomposites Observed by SANS During Annealing
摘要：
利用对比度变化小角中子散射研究了二氧化硅-胶乳纳米复合材料在纳米复合材料形成和退火过程中聚合物结构的演变。实验系统由二氧化硅纳米颗粒（Rsi \approx 8 nm）和专门合成的氢化和氘代纳米胶乳的混合物（Rlatex \approx 12.5 nm）制成。通过链相互扩散和释放在纳米复合材料中的胶乳珠粒的逐步消失进行了定量分析与模型的分散强度的毛状胶乳珠粒和RPA描述的自由链。在无二氧化硅的基质和低二氧化硅含量（7%v）的纳米复合材料中，在高达Tg + 85 K下的数周的退火程序导致链的分子分散，其回转半径被报道。在更高的二氧化硅含量（20%v），链相互扩散似乎在几周的时间尺度上减慢，仅在最强退火时达到分子分散。链的回转半径被发现是不受二氧化硅填料的存在下。
英文摘要：
The evolution of the polymer structure during nanocomposite formation and annealing of silica-latex nanocomposites is studied using contrast-variation small angle neutron scattering. The experimental system is made of silica nanoparticles (Rsi \approx 8 nm) and a mixture of purpose-synthesized hydrogenated and deuterated nanolatex (Rlatex \approx 12.5 nm). The progressive disappearance of the latex beads by chain interdiffusion and release in the nanocomposites is analyzed quantitatively with a model for the scattered intensity of hairy latex beads and an RPA description of the free chains. In silica-free matrices and nanocomposites of low silica content (7%v), the annealing procedure over weeks at up to Tg + 85 K results in a molecular dispersion of chains, the radius of gyration of which is reported. At higher silica content (20%v), chain interdiffusion seems to be slowed down on time-scales of weeks, reaching a molecular dispersion only at the strongest annealing. Chain radii of gyration are found to be unaffected by the presence of the silica filler.
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