Surface Modification of Nanoclay for the Synthesis of Polycaprolactone (PCL) – Clay Nanocomposite

Abstract

Abstract. This paper presents a new modification method to modify the surface of nanoclay (Na-MMT) to increase its d-spacing using Aminopropylisooctyl Polyhedral Oligomeric Silsesquioxane (AP-POSS) and the fabrication of Polycaprolactone (PCL) nanocomposite through solution intercalation technique. The structure and morphology of pure nanoclay, modified nanoclay (POSS-MMT) and the PCL nanocomposite were characterized by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Field Emission Scanning Electron Microscopy (FESEM). XRD revealed that the d-spacing of the POSS-MMT is increased by 0.64 nm as compared to pure nanoclay. FTIR and FESEM results also showed that AP-POSS were well dispersed and intercalated throughout the interlayer space of Na-MMT. An exfoliated structure was also observed for PCL/POSS-MMT nanocomposite. Thermal properties of the nanocomposite were investigated using Thermal Gravimetry Analysis (TGA) which recorded highest degradation temperature for PCL/POSS-MMT 1% nanocomposite which is 394.1˚C at 50% weight loss (T50%) but a decrease in degradation temperature when POSS-MMT content is increased and Differential Scanning Calorimetry (DSC) analysis which showed highest melting and crystallization temperature for PCL/POSS-MMT 5% nanocomposite which is 56.6˚C and 32.7˚C respectively whereas a decrease in degree of crystallinity for PCL/POSS-MMT nanocomposite as compared to PCL/Na-MMT nanocomposite. This study affords an efficient modification method to obtain organoclay with larger interlayer d-spacing to enhance the properties of polymer nanocomposite.

A Review of the Synthesis and Applications of Polymer–Nanoclay Composites

“…The most common plate-like montmorillonite (MMT) nanoclay (smectite) consists of approximately one nm thick aluminosilicate layers surface-substituted with metal cations and stacked in approximately 10 µm-sized multilayer stacks [12]. The stacks can be dispersed in a polymer matrix as fillers/additives to form polymer/nanoclay composites, with applications such as mechanical strength enhancement, flame-resistance material, thickening and gelling agents, waste water treatment and gas permeability modification [12][13][14][15]. MMT nanoclay (2:1 layered silicates) with a high cation exchange capacity has cation exchange sites on the siloxane surface which can be combined with dissimilar substances, such as organic or biological molecules [16].…”

“…These nanoclays are also used as carriers to achieve a sustained release of active molecules, such as flame-retardants, antioxidants, anticorrosion and antimicrobial agents [21,22]. The research and development of novel polymer/nanoclay materials has been an advancing field in material chemistry in recent years [9,[12][13][14][15][23][24][25]. Rigid nanoclay may be used as a filler and is able to reinforce polymer structures and impede the free movement of polymer chains neighboring the filler [19].…”

<p>Electrospraying Oxygen-Generating Microparticles for Tissue Engineering Applications</p>

“…All the important peaks of the PCL such as the 2945 cm −1 correspond to bands associated to the vibrations of asymmetric elongation υ as (CH 2 ); symmetrical stretch υ s (CH 2 ) at 2865 cm −1 ; carbonyl elongation at 1725 cm −1 υ(C=O), 1473, 1397, and 1361 cm −1 (CH 2 ) bending; elongation in the crystalline phase at 1295 cm −1 υ cr (C-O; C-C); asymmetrical stretching υ as (C-O-C) at 1241 cm −1 ; and stretching vibration ν(OC-O) at 1188 cm −1 were also identified ( Figure 3B-ii). [40][41][42][43] Moreover, the characteristic bands of PCL were also observed in the PCL-CPO-M and PCL-F-CPO-M spectra as well as the presence of the CPO by the appearance of the band at 875 cm −1 (Figure 3B-iii-iv). The absence of the 1479 and 3700 cm −1 bands of CPO can be attributed to the interactions of the oxygen in the OH and CaO 2 with the polymers.…”

In-situ Composite Formation by Polymerization on the Hectorite or other Clay Materials

“…The most common lamellar nanoclay of montmorillonite (smectite) (MMT) consists of layers of aluminosilicates about 1 nm thick, the surface of which is replaced by metal cations and is stacked in several layers about 10 μm in size. In the polymer matrix stacking agents can be dispersed as a filler/additive for forming polymer/composites of nanoclay, which has various applications as increased mechanical strength thickening and gelling conditioners, flame retardant materials, wastewater treatment and air permeability control [5][6][7][8]. MMT nanoclays (2:1 subclass silicates) with the high exchanging ability of cations such as biological or organic molecules have sites for the exchange of cations on the siloxane surface that could be bound to various substances [9].…”

“…To get continuous delivery of active molecules like flame retardants, antioxidants, anticorrosive and antibacterial agents, these nanolayers are also used as a means [14,15]. In recent years R&D of new polymer/nanoclay materials is an area of progress in material chemistry [3,[6][7][8][16][17][18][19]. A rigid nanolayer can be used as a filler and can strengthen the macromolecular structure and prevent freely moving polymer chains around the filler [13].…”