Synthesis of Poly(methyl methacrylate) Nanocomposites via Emulsion Polymerization Using a Zwitterionic Surfactant

Abstract

The synthesis of nanocomposites via emulsion polymerization was investigated using methyl methacrylate (MMA) monomer, 10 wt % montmorillonite (MMT) clay, and a zwitterionic surfactant octadecyl dimethyl betaine (C18DMB). The particle size of the diluted polymer emulsion was about 550 nm, as determined by light scattering, while the sample without clay had a diameter of about 350 nm. The increase in the droplet size suggests that clay was present in the emulsion droplets. X-ray diffraction indicated no peak in the nanocomposites. Transmission electron microscopy showed that emulsion polymerization of MMA in the presence of C18DMB and MMT formed partially exfoliated nanocomposites. Differential scanning calorimetry showed an increase of 18 °C in the glass transition temperature (T g) of the nanocomposites. A dynamic mechanical thermal analyzer also verified a similar T g increase, 16 °C, for the partially exfoliated nanocomposites over poly(methyl methacrylate) (PMMA). Thermogravimetric analysis indicated a 37 °C increase in the decomposition temperature for a 20 wt % loss. A PMMA nanocomposite with 10 wt % C18DMB−MMT was also synthesized via in situ polymerization. This nanocomposite was intercalated and had a T g 10° lower than the emulsion nanocomposite. The storage modulus of the partially exfoliated emulsion nanocomposite was superior to the intercalated structure at higher temperatures and to the pure polymer. The rubbery plateau modulus was over 30 times higher for the emulsion product versus pure PMMA. The emulsion technique produced nanocomposites of the highest molecular weight with a bimodal distribution. This reinstates that exfoliated structures have enhanced thermal and mechanical properties over intercalated hybrids.

Preparation and characterization of zwitterionic surfactant-modified montmorillonites

“…Therefore, the zwitterionic surfactant-modified montmorillonites (ZSMMs) may have high sorption capacities towards cationic organic pollutants via electrostatic interactions. However, until now few studies were done on ZSMMs, and the properties and microstructures of ZSMMs are still unclear [28][29][30].…”

Novel polyacrylonitrile/Na-MMT/silica nanocomposite: Co-incorporation of two different form nano materials into polymer matrix

“…The nanocomposites exhibit impressive enhancements of material properties as compared with the pure polymers, and have many potential applications in aerospace materials, structural materials, electronics, sensors and other areas [1][2][3][4][5][6][7][8][9][10]. Among various nanocomposites, much attention has been paid to polymer/ MMT nanocomposites [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28], because they have high stiffness [11,12], enhanced mechanical property [13][14][15][16][17]23], high thermal stability [16,18,23], flame-retarding [19,20], and better barrier properties [21,22] even with small amount of silicate. For instance, Strawhecker and Manias [23] studied the structure and properties of poly(vinyl alcohol)/Na-MMT nanocomposites.…”

Influence of drying procedure on glass transition temperature of PMMA based nanocomposites

“…Also in PMMA/clay nanocomposites, large increases were found. 18,19 In Table 1, an overview of PMMA based nanocomposites and their corresponding glass transition temperatures can be found. As stated before, an increase in the glass transition temperature is observed in most cases.…”