Scalable Fabrication of Nano-Objects with Soft Polysiloxane Core and Functional Application as Toughening or Flame-Retardant Additives

Polysiloxane has found extensive applications in advanced composite materials. However, the low compatibility with most polymers always resulted in the formation of macroscopic phase separation and thus limited its functional utilization to a maximum extent. Self-assembly of block copolymers has been developed as an efficient technique for preparing nanomaterials by selectively allocating each block at the core or shell region, thus facilitating multiple applications. However, the scalable fabrication and functional application of nano-objects with a soft polysiloxane core remain challenging, despite being boosted with theoretical significance and urgent applications. To this aim, herein, the poly(methyl methacrylate)-b-poly(dimethylsiloxane-co-vinylmethylsiloxane)-b-poly(methyl methacrylate) (PMMA-b-P(DMS-co-VMS)-b-PMMA, MSM) triblock copolymers were first designed and synthesized. Subsequently, employing a heat-induced self-assembly (HISA) process, the nano-objects with regular morphologies and controlled sizes were prepared in selective solvents and further stabilized by in situ cross-linking of the P(DMS-co-VMS) core. The observed low melting temperature (Tm) of the P(DMS-co-VMS) core confirmed that the soft polysiloxane core was successfully fabricated. The nano-objects with regular morphologies, controlled sizes, adjustable cross-linking densities, tunable PMMA contents, and block lengths significantly enhanced the toughening behavior and flame-retardant performance of PMMA-based composites, which were obviously superior to the counterpart of MSM triblock copolymer with undefined microphase. The HISA has proven to be an efficient technique for fabricating nano-objects with a soft polysiloxane core, which demonstrates significant potential as functional additives in practical applications.