Enhancement of Modulus, Strength, and Toughness in Poly(methyl methacrylate)‐Based Composites by the Incorporation of Poly(methyl methacrylate)‐Functionalized Nanotubes

Abstract

Poly(methyl methacrylate) (PMMA)‐functionalized multiwalled carbon nanotubes are prepared by in situ polymerization. Infrared absorbance studies reveal covalent bonding between polymer strands and the nanotubes. These treated nanotubes are blended with pure PMMA in solution before drop‐casting to form composite films. Increases in Young's modulus, breaking strength, ultimate tensile strength, and toughness of ×1.9, ×4.7, ×4.6, and ×13.7, respectively, are observed on the addition of less than 0.5 wt % of nanotubes. Effective reinforcement is only observed up to a nanotube content of approximately 0.1 vol %. Above this volume fraction, all mechanical parameters tend to fall off, probably due to nanotube aggregation. In addition, scanning electron microscopy (SEM) studies of composite fracture surfaces show a polymer layer coating the nanotubes after film breakage. The fact that the polymer and not the interface fails suggests that functionalization results in an extremely high polymer/nanotube interfacial shear strength.

Advanced multifunctional graphene aerogel – Poly (methyl methacrylate) composites: Experiments and modeling

“…The presence of m-rGO sheets is likely to generate numerous obstacles and interlock the motion of shear bands in the polymer matrix, which might offer a better resistance to plastic deformation and achieve more efficient load transfer [27]. Furthermore, the impact of the nucleation of a rGO-PMMA interfacial region might also be significant, which is likely to be much stiffer and may probably result in better stress transfer than the rest of its amorphous bulk [67].…”

Grafting Polymer Loops onto Functionalized Nanotubes: Monitoring Grafting and Loop Formation

“…Testard et al conducted a Monte Carlo study of the loop and bridge formation between colloidal particles by telechelic polymers. [58] In this study, the ratio of the distance between the particles h to the R g of the telechelic free chain was varied, where b ¼ h=R g (6) It was discovered that approximately 20%-30% of the telechelics formed bridges from b ¼ 0-1, that is, for particle distances ranging from contact up to the R g of the free telechelic. The fraction of bridges decayed significantly as the value of b increased from 1 to 2.…”

“…In order to determine the mechanism limiting the grafting reaction in this experiment, the amount of polymer chains grafted as a function of reaction time t can be described by a power law equation, y ¼ at m , where a is a constant. To determine the time-dependent power m of the equation, the log of the normalized absorbance y is plotted as a function of the log of the reaction or annealing time t in logðyÞ ¼ m logðtÞ þ logðaÞ (6) Applying this analysis, the grafting rate of the polymer chains was followed by observing the normalized 820 cm À1 absorbance as a function of reaction time in NMP, shown in Figure S8 (see the SI). The plot in Figure S8 is reasonably linear for the 6 d of reaction in NMP, indicating a slope of 0.279, that is, the grafting rate is proportional to approximately t 0.3 .…”

“…In addition, the grafted chains suppress the agglomeration of the nanotubes by steric hindrance. [4] Polymer nanocomposites made with small amounts of monofunctional polymer chains grafted to the nanotubes have been shown to greatly improve the mechanical properties of the composite, [5][6][7] and are more effective than ungrafted pristine nanotubes in this regard. [8] The grafting of polymer chains to nanotubes can be achieved by functionalizing the nanotube in order to introduce reactive groups onto the surface, followed by reaction with a polymer chain possessing a complementary reactive end group.…”

Optimization of molecular structure of polythiophene-graft-PMMA for effective compatibilization of SAN/MWCNT composite with superior mechanical properties

“…However, to achieve the effective transfer of remarkable mechanical properties of CNTs to polymer matrix, CNTs should be homogeneously dispersed in polymer matrix and possess a strong interfacial interaction with polymer matrix because these requirements lead to the efficient load transfer across the polymer-CNTs interface [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. Generally, as-produced CNTs self-assemble in aggregated bundles where individual CNTs are held together by van der Waals attraction, which limits the potential of CNTs as a reinforcing filler.…”