In Situ Thermal Reduction of Graphene Nanosheets Based Poly(methyl methacrylate) Nanocomposites with Effective Reinforcements

Generation of Polymer Nanocomposites through Shear-Driven Aggregation of Binary Colloids

Design of polymer nanocomposites has been an intense research topic in recent decades because hybrid nanomaterials are widely used in many fields. Throughout their development, there has often been a challenging issue how one can uniformly distribute nanoparticles (NPs) in a polymer matrix, avoiding their agglomeration. In this short review, we first introduce the theory of colloidal aggregation/gelation purely based on intense shear forces. Then, we illustrate a methodology for preparing polymer nanocomposites where the NPs (as fillers) are uniformly and randomly distributed inside a matrix of polymer NPs, based on intense shear-driven aggregation of binary colloids, without using any additives. Its feasibility has been demonstrated using two stable binary colloids composed of (1) poly-methyl methacrylate fillers and polystyrene NPs, and (2) graphene oxide sheets (fillers) and poly-vinylidene fluoride NPs. The mechanism leading to capturing and distribution of the fillers inside the polymer NP matrix has been illustrated, and the advantages of the proposed methodology compared with the other common methods are also discussed.

In situ repair of graphene defects and enhancement of its reinforcement effect in polyvinyl alcohol hydrogels

The reactive groups on the edge of graphene defects are activated at a low γ-ray irradiation dose, and the resulting PVA scission chains at the high γ-ray dose link these reactive groups to repair the graphene defects.

Uniform distribution of graphene oxide sheets into a poly-vinylidene fluoride nanoparticle matrix through shear-driven aggregation

A general methodology has been developed for preparing nanocomposites with uniform, random distribution of fillers in polymer matrices, purely based on intense shear-driven aggregation, while avoiding filler aggregation. This procedure is demonstrated for a binary colloid composed of graphene oxide (GO) sheets and poly-vinylidene fluoride (PVDF) nanoparticles (NPs), both negatively charged and stable at rest. On the other hand, the PVDF NPs are shear-active (i.e. aggregation occurs under intensive shear), while the GO sheets are shear-inactive. It is found that when the two suspensions are mixed and the resulting binary colloid is forced to pass through a microchannel (MC) device (at a very high shear rate, G = 1.2 × 10(6) s(-1)), the shear-inactive GO sheets are captured and well distributed inside the PVDF NP clusters or gels. In addition, it is shown that in order to have 100% capture efficiency for the GO sheets, a minimum solid content of the binary colloid is required, which can be identified experimentally as the minimum leading to gelation after passing through the MC only one time.

Mechanical properties of polymer composites reinforced by functionalized graphene prepared via direct exfoliation of graphite flakes in styrene

By incorporating FGs into PS matrix appropriately, the obtained PS/FGs exhibit dramatic enhancement in mechanical properties.

Ultrathin Nanosheets of Organic-Modified β-Ni(OH)2 with Excellent Thermal Stability: Fabrication and Its Reinforcement Application in Polymers

β-Nickel hydroxide (β-Ni(OH)2), which combines two-dimensional (2D) structure and the catalytic property of nickel-containing compounds, has shown great potential for the application in polymer nanocomposites. However, conventional β-Ni(OH)2 exhibits large thickness, poor thermal stability, and irreversible aggregation in polymer matrices, which limits its application. Here, we use a novel phosphorus-containing organosilane to modify the β-Ni(OH)2 nanosheet, obtaining a new β-Ni(OH)2 ultrathin nanosheet with excellent thermal stability. When compared to pristine β-Ni(OH)2, the organic-modified β-Ni(OH)2 (M-Ni(OH)2) maintains nanosheet-like structure, and also presents a small thickness of around 4.6 nm and an increased maximum degradation temperature by 41 °C. Owing to surface organic-modification, the interfacial property of M-Ni(OH)2 nanosheets is enhanced, which results in the exfoliation and good distribution of the nanosheets in a PMMA matrix. The addition of M-Ni(OH)2 significantly improves the mechanical performance, thermal stability, and flame retardancy of PMMA/M-Ni(OH)2 nanocomposites, including increased storage modulus by 38.6%, onset thermal degradation temperature by 42 °C, half thermal degradation temperature by 65 °C, and decreased peak heat release rate (PHRR) by 25.3%. Moreover, it is found that M-Ni(OH)2 alone can catalyze the formation of carbon nanotubes (CNTs) during the PMMA/M-Ni(OH)2 nanocomposite combustion, which is a very helpful factor for the flame retardancy enhancement and has not been reported before. This work not only provides a new 2D ultrathin nanomaterial with good thermal stability for polymer nanocomposites, but also will trigger more scientific interest in the development and application of new types of 2D ultrathin nanomaterials.

Recent advances in graphene/polyamide 6 composites: a review

This paper reviews recent years’ (2009–2015) advances in graphene/PA6 nanocomposites for the first time.