We study the interfacial energy parameters that explain the reinforcement of polymers with nanodiamond (ND) and the development of mechanical strength of electrospun ND-reinforced composites. Thermodynamic parameters such as the wettability ratio, work of spreading and dispersion/aggregation transition are used to derive a criterion to predict the dispersibility of carboxylated ND (cND) in polymeric matrices. Such a criterion for dispersion (D_c) is applied to electrospun cND-containing poly(vinyl alcohol) (PVA), polyacrylonitrile (PAN), and polystyrene (PS) fiber composites. The shifts in glass transition temperature (ΔT_g), used as a measure of polymer/cND interfacial interactions and hence the reinforcement capability of cNDs, reveal a direct correlation with the thermodynamic parameter D_c in the order of PAN < PS < PVA. Contrary to expectation, however, the tensile strength of the electrospun fibers correlates with the D_c and ΔT_g only for semicrystalline polymers (PAN < PVA) while the amorphous PS displays a maximum reinforcement with cND. Such conflicting results reveal a synergy that is not captured by thermodynamic considerations alone but also factor in the contributions of polymer/cND interface stress transfer efficiency. Our findings open the possibility for tailoring the interfacial interactions in polymer–ND fiber composites to achieve maximum mechanical reinforcement.

中文翻译：

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纳米金刚石增强聚合物纤维的界面贡献

我们研究了解释用纳米金刚石 (ND) 增强聚合物和电纺 ND 增强复合材料机械强度发展的界面能参数。热力学参数如润湿比、铺展功和分散/聚集转变用于推导预测羧化 ND (cND) 在聚合物基质中的分散性的标准。这种分散标准 ( D _c ) 适用于电纺含 cND 的聚乙烯醇 (PVA)、聚丙烯腈 (PAN) 和聚苯乙烯 (PS) 纤维复合材料。玻璃化转变温度的变化 (Δ T _g)，用作衡量聚合物/cND 界面相互作用并因此衡量 cND 的增强能力，揭示了与热力学参数D _c的直接相关性，其顺序为 PAN < PS < PVA。然而，与预期相反，电纺纤维的拉伸强度与D _c和ΔT _{g 相关}仅适用于半结晶聚合物（PAN < PVA），而无定形 PS 显示出与 cND 的最大增强。这种相互矛盾的结果揭示了一种协同作用，这种协同作用不仅仅被热力学考虑所捕获，而且还影响了聚合物/cND 界面应力转移效率的贡献。我们的发现为调整聚合物-ND 纤维复合材料中的界面相互作用以实现最大的机械增强提供了可能性。