The poly(amidoamine) (PAMAM) dendrimer-grafted silica nanoparticles were utilized as a curing and composite agent for epoxy-terminated polyurethane (PU). For this purpose, surface-hydroxylated silica nanoparticles (SiH) were modified with (3-aminopropyl)triethoxysilane to obtain the core for PAMAM dendrimer synthesized via consecutive addition of methyl acrylate and ethylenediamine. Effect of different chain extenders, pyromellitic dianhydride (PMDA) and 1,4-butanediol (BD), on thermal characteristics of the composites was also studied in detail. Successful incorporation of PMDA and BD chain extenders and also epoxy groups to the PU backbone was confirmed by proton nuclear magnetic resonance analysis. Chemical modification of silica nanoparticles via PAMAM dendrimer in each of the generation steps was studied using Fourier-transform infrared spectroscopy and also their thermal degradation characteristics. The thermogravimetric analysis results proved that increasing content of the PAMAM-modified silica nanoparticles in combination with incorporation of PMDA as the chain extender resulted in higher thermal stabilities of the PU composites. The cured epoxy-modified PU with PMDA chain extender showed higher char residue compared with the cured epoxy-modified PU with BD chain extender (7.1 against 0.8%). X-ray diffraction analysis confirmed amorphous nature of silica and the PU composites. Scanning and transmission electron microscopies were also used for morphological investigation of the pure and PAMAM-modified silica in addition to the PU composite.

聚（酰胺胺）（PAMAM）树枝状聚合物接枝的二氧化硅纳米粒子被用作环氧封端聚氨酯（PU）的固化和复合剂。为此，表面羟基化二氧化硅纳米粒子 (SiH) 用（3-氨基丙基）三乙氧基硅烷改性，以获得通过连续添加丙烯酸甲酯和乙二胺合成的 PAMAM 树枝状聚合物的核心。还详细研究了不同扩链剂、均苯四酸二酐 (PMDA) 和 1,4-丁二醇 (BD) 对复合材料热特性的影响。质子核磁共振分析证实了 PMDA 和 BD 增链剂以及环氧基团成功掺入 PU 主链。使用傅里叶变换红外光谱研究了在每个生成步骤中通过 PAMAM 树枝状聚合物对二氧化硅纳米粒子的化学改性及其热降解特性。热重分析结果证明，增加 PAMAM 改性二氧化硅纳米粒子的含量并结合 PMDA 作为扩链剂可提高 PU 复合材料的热稳定性。与带有 BD 增链剂的固化环氧改性 PU 相比，带有 PMDA 增链剂的固化环氧改性 PU 显示出更高的炭残留（7.1 对 0.8%）。X 射线衍射分析证实了二氧化硅和 PU 复合材料的无定形性质。