Elsevier

Applied Surface Science

Volume 258, Issue 7, 15 January 2012, Pages 2404-2409
Applied Surface Science

Surface modification of magnesium aluminum hydroxide nanoparticles with poly(methyl methacrylate) via one-pot in situ polymerization

https://doi.org/10.1016/j.apsusc.2011.10.059Get rights and content

Abstract

Hydrophobic magnesium aluminum hydroxide composite particles (PMMA-MAH) were obtained by means of grafting poly(methyl methacrylate) (PMMA) onto the surface of magnesium aluminum hydroxide(MAH) nanoparticles after a novel type of phosphate coupling agent (DN-27) modification. The introduction of functional double bonds was firstly conducted on the surface of nanoparticles by DN-27 modification, followed by one-pot in situ polymerization on the particles surface using methyl methacrylate (MMA) as monomer, azoisobutyronitrile (AIBN) as initiator and sodium dodecyl sulfate (SDS) as stabilizer to graft PMMA on the surface of DN-27-modified MAH particles. The obtained composite particles were characterized by field-emission scanning electron microscope (FESEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), X-ray powder diffraction (XRD). The results show that the organic macromolecule PMMA could be successfully grafted on the surface of DN-27-modified MAH nanoparticles and the thermal stability of the PMMA-MAH composite particles had been improved. Compared with unmodified blank MAH sample, the product obtained with this method possesses better hydrophobic properties such as a higher water contact angle of 108° and a well dispersion.

Highlights

► DN-27 is applied to the surface modification of MAH nanoparticles by grinding method. ► Hydrophobic PMMA-MAH particles are obtained by a simple one-pot in situ polymerization reaction. ► The thermal stability of the PMMA-MAH composite particles had been improved. ► The sample obtained possesses a higher water contact angle of 108°.

Introduction

In recent years, there has been a trend towards the use of halogen-free flame retardant because of its advantages, such as low smoke, no toxicity, and no carcinogenic gas generation [1], [2], [3]. Many investigations have demonstrated that magnesium hydroxide (MH), aluminum hydroxide (AH) and magnesium aluminum hydroxide (MAH) are environmentally friendly additives and can be used in polymer materials for manufacturing halogen-free and low-smoke cables [4], [5], [6], [7], [8], [9]. However, the above hydroxides exist some disadvantages, such as high loadings and poor compatibility with the polymeric materials, which degraded the mechanical properties [10], [11]. Therefore, it is very necessary to modify the surface of particles to improve their dispersion in polymers. The surface treating method using by low-molecular weight coupling agents or surfactants has been found to be reasonably effective [12], [13], [14], [15], [16], [17], [18]. But low-molecular weight compounds have a tendency to migrate out from the interface to the surface of the composites, inevitably, there is decrease in the mechanical and physical properties of the composite materials. Nowadays, polymer modification on inorganic particles has become a more interesting method to improve their dispersibility and compatibility in organic phrase and polymer composite [19], [20], [21]. Because of their layered structure and high anion-exchange capacity, MAH nanoparticles have attracted much attention [22], [23], [24], [25], [26], [27]. The intercalation of guest species in crystalline layered host matrices is considered to be a versatile synthetic method for the synthesis of nanostructured hybrid materials [28], [29]. However, there have been few reports on the surface grafting of MAH. On account of it is easy to get and prone to react [13], [30], MMA monomer was used in this experiment.

In the present paper, a novel type of phosphate coupling agent, DN-27 is first applied to the surface modification of MAH nanoparticles by grinding method, then hydrophobic PMMA-MAH particles are obtained by a simple one-pot in situ polymerization reaction.

Section snippets

Materials

The reagents that used in this work were listed in Table 1. All the above chemicals were analytically pure and used as received without further purification except MMA, which was distilled at a reduced pressure at 50 °C. AIBN was dissolved in DMF and recrystallized in ethanol twice for purification. DN-27 is a novel type of phosphate coupling agent and its formula can be expressed as ((CH3)2CHO)2P(O)O(CH2CH2O)10C6H4OC(O)C(CH3)CH2, which can be named as

DN-27 modification

Generally speaking, MAH nanoparticles are hard to graft MMA on their surface directly. In order to easily polymerize MMA monomer, DN-27 was used to modify the surfaces of the nanoparticles to introduce double bond. DN-27 is a novel type of phosphate coupling agent with unsaturated double bond. That makes it facilitate the polymerization of MMA monomers on MAH nanoparticles. Firstly, DN-27 coated in MAH nanoparticles by grinding reaction to introduce unsaturated double bond onto the surface of

Conclusions

MAH nanoparticles were obtained with the mean size of 80 nm and high purity. PMMA was grafted on the magnesium aluminum hydroxide nanoparticles after DN-27 modification. MMA monomers polymerized on the nanoparticle surfaces via the double bond of DN-27. The compatibility and the thermal stability of the PMMA-MAH composite particles had been improved greatly. This is very helpful to the flame retardant performance of magnesium aluminum hydroxide composite particles when added in the polymer

Acknowledgements

The work was financially supported by National Natural Science Foundation of China (No. 20873101), Natural Science Foundation of Gansu Province (No. 2007GS03562), Scientific Research Fund of Gansu Provincial Education Department (No. 1001-08) and Key Laboratory of Polymer Materials of Gansu Province.

References (31)

Cited by (32)

  • Flame retardant treatments for polypropylene: Strategies and recent advances

    2021, Composites Part A: Applied Science and Manufacturing
    Citation Excerpt :

    The former mainly improves the interfacial bonding between the inorganic filler and the organic polymer by changing the surface properties of the inorganic filler through surface treatment, via adding the compatibilizer and through copolymerization or grafting of monomer to improve the interaction between the matrix and the filler. The interaction is mainly based on the degree of adhesion between the additive and the polymer matrix, such as coupling agents, polypropylene grafted maleic substitution (PP-g-MAH), alkyl silicone oil, polyvinyl alcohol [180-184]. The latter makes greater use of the synergism of flame retardants, such as the presence of nanomaterials and the addition of transition metals.

  • Highly efficient and selective removal of low-concentration antibiotics from aqueous solution by regenerable Mg(OH)<inf>2</inf>

    2020, Journal of Environmental Sciences (China)
    Citation Excerpt :

    Therefore, it has been widely used to remove aromatic organic pollutants in aqueous solution. Actually, various adsorbents including carbonaceous materials, metallic oxides, and layered hydroxide have been applied with Aww (Yu et al., 2016; Guo et al., 2012; Sui et al., 2012). For example, it was reported that microporous activated carbon (ACC) with its unique porous structure and rich surface-active functional groups could adsorb multiple fluoroquinolone antibiotics in aqueous solution (ciprofloxacin (CIP), norfloxacin (NOR), etc.) (Fu et al., 2016).

  • Surface modification of magnesium hydroxide by wet process and effect on the thermal stability of silicone rubber

    2019, Applied Surface Science
    Citation Excerpt :

    In addition, a high loading of MH is usually required to guarantee the desired flame retardant effect, which leads to sharply decline in the mechanical properties and rheological properties of the polymers [12–15]. Surface modification has been demonstrated as a simple and effective approach to afford MH with hydrophobicity and improve the dispersion stability of MH in polymers [16–18]. Among various modifier, silane coupling agent has attracted much attention due to its amphiphilicity [19–21].

  • Preparation of β-cyclodextrin-ester network and new organo-modified LDH as dual additives of PVA: Thermal, dynamic-mechanical and migration study

    2017, Progress in Organic Coatings
    Citation Excerpt :

    However, low-molecular weight agents have a propensity to migrate out from the interface to the surface of the composite and this phenomenon inevitably causes a decrease in the mechanical and physical properties of the composite materials. Therefore, theirmigration control from the composite materials is very important [25–31]. β-Cyclodextrin (β-CD) is a non-toxic cyclic oligosaccharide which is made of seven glucose units, linked by 1,4-α-glucosidic bonds, containing a hydrophilic outer surface and a hollow hydrophobic interior.

  • Surface modification of magnesium hydroxide using vinyltriethoxysilane by dry process

    2016, Applied Surface Science
    Citation Excerpt :

    The on-line modification could short the process line and obtain ultrafine MH, due to modification and preparation of MH can be acted on simultaneously [17,18]. In the case of dry process and wet process methods, there are versatile surface modifiers, such as fatty acids, titanate coupling agent, silane coupling agents, and so on [19–22], can be chosen for prepared MH. Silane coupling agent has gained more research attention due to its unique structure, which contains two different functional groups: one that is attracted to the resin, and the other that reacts with hydroxyl groups on the surface of the filler [23–25].

View all citing articles on Scopus
View full text