One-pot solvothermal synthesis of silane-functionalized carbon nanodots as compatibilizers for the immiscible TPU/MVQ blends

Herein, silane-functionalized carbon nanodots (Si-CDs) with different sizes and surface grafting density were successfully fabricated by a facile and cost-effective one-pot solvothermal treatment and incorporated for the first time as novel compatibilizers into the thermoplastic polyurethane/methyl vinyl silicone rubber (TPU/MVQ) blends. As obtained fluorescent Si-CDs with a size of 2 nm and functionalized with maximum amido and silane chains, called Si-CDs-High, displayed better compatibilizing efficiency than other Si-CDs with large size and low grafting density. The average diameter of MVQ domain in the blend reduced sharply from 2.51 +/- 1.03 mu m to 0.91 +/- 0.28 mu m at a small content of 1 wt% of Si-CDs-High. As effective compatibilizers, Si-CDs-High were located at the interface and formed a stable interface layer between TPU and MVQ phases and the thickness of interface was quantitatively identified by using Atomic Force Microscope. The superior compatibilizing efficiency of Si-CDs-High can be attributed that such Si-CDs with sufficient chains and groups can not only prevent coalescence of polymer domains by rigid nanoparticle core but also enhance interfacial adhesion due to the molecular entanglements and hydrogen bonding. Furthermore, the polymer blends with Si-CDs-High exhibited enhanced mechanical property, thermal stability and tunable fluorescent properties. This strategy compatibilized by fluorescent Si-CDs paves a new possibility for advanced blend nanocomposites.