In-Situ Intercalate polymerization

Similarly to FeOCl, V205.nH20 is also capable of undergoing in situ intercalation/ polymerization. The intercalation of polyaniline, polypyrrole, and polythiophene into... 

VOPO4.2H2O is capable of undergoing in situ intercalation/polymerization with molecules such as aniline [50, 51], substituted anilines [52,53,54], and pyrroles [55]. Evidence of intercalation was obtained from powder X-ray diffraction. As an example, the powder pattern of poly(A-methylaniline) (PMA) intercalated into VOPO4 is illustrated in Figure 6.11. The identity of the intercalated polymer was confirmed by Fourier-transform infrared studies. 

ENGAGE is an ethylene-octene copolymer. Ray and Bhowmick [70] have prepared nanocomposites based on this copolymer. In this study, the nanoclay was modified in situ by polymerization of acrylate monomer inside the gallery gap of nanoclay. ENGAGE was then intercalated inside the increased gallery gap of the modified nanoclay. The nanocomposites prepared by this method have improved mechanical properties compared to that of the conventional counterparts. Preparation and properties of organically modified nanoclay and its nanocomposites with ethylene-octene copolymer were reported by Maiti et al. [71]. Excellent improvement in mechanical properties and storage modulus was noticed by the workers. The results were explained with the help of morphology, dispersion of the nanofiller, and its interaction with the mbber. 

The main techniques that can be used to prepare polymer/clay nanocomposites are (a) melt mixing the layered clay with polymer, (b) mixing the layered clay with solution of polymer followed by solvent removal, and (c) in situ intercalative polymerization, where the monomer is first intercalated in the clay and subsequently polymerized in situ. 

Besides melt intercalation, described above, in situ intercalative polymerization of E-caprolactone (e-CL) has also been used [231] to prepare polycaprolactone (PCL)-based nanocomposites. The in situ intercalative polymerization, or monomer exfoliation, method was pioneered by Toyota Motor Company to create nylon-6/clay nanocomposites. The method involves in-reactor processing of e-CL and MMT, which has been ion-exchanged with the hydrochloride salt of aminolauric acid (12-aminodecanoic acid). Nanocomposite materials from polymers such as polystyrene, polyacrylates or methacrylates, styrene-butadiene rubber, polyester, polyurethane, and epoxy are amenable to the monomer approach. 

Figure 6.1 Structural model for the Intercalated polypyrrole chains within the van der Waals gap of FeOCI. (Reprinted with permission from Solid State Ionics, In situ intercalative polymerization chemistry of FeOCI. Generation and properties of novel, highly conductive Inorganic/organic polymer microlaminates by M. G. Kanatzidis, H. O. Marcy, W. J. McCarthy et al., 594-608, 1-3. Copyright (1989) Elsevier Ltd)...

P. Liu and K. Gong, Synthesis of polyaniline-intercalated graphite oxide by an in situ oxidative polymerization reaction. Carbon, 37, 706-707 (1999). 

PANI/tin oxide-intercalated nanocomposite (PANI-SnO ) In-situ chemical polymerization Dip coating on glass substrate NH3 [18]... 

Several techniques such as intercalation of polymer from solution, in-situ intercalative polymerization, melt intercalation, direct mixture of polymer and particulates, template synthesis, in-situ polymerization and solgel process, are being employed for the preparation of polmer-layered silicate nanocomposites. Among them the most common and important approaches are in-situ polymerization, solution-induced intercalation method, and melt processing method, which are briefly discussed below. 

In the melt mixing method, nanoclays are incorporated into the polymer in the molten state. This technique has considerable advantages over either the in situ intercalative polymerization or polymer solution intercalation techniques. Firstly, this method is environmentally benign due to the absence of organic solvents. Secondly, melt processing is compatible with current industrial processes, such as extrusion and injection moulding. The melt intercalation method allows the use of biopolymers that were not suitable for in situ polymerization. This has been the most widely used method in the literature for obtaining PLA/clay nanocomposites. " ... 

The structure and dynamics of surfactant and polymer chains in intercalated poly(8-caprolactone)/ clay nanocomposites are characterized by P magic-angle spinning (MAS) and C cross-polarization MAS NMR techniques. To obtain hybrid materials with the low polymer content required for this study, in situ intercalative polymerization was performed by adapting a published procedure. After nanocomposite formation, the chain motion of the surfactant is enhanced in the saponite-based materials but reduced in the laponite ones. Compared to the initial clay, the trani -conformer population of the surfactant hydrocarbon chains in the nanocomposite decreases for the saponite systems. Mobility of the polymer chain is higher in the nanocomposites than in the bulk phase. The charge of the modified saponite does not significantly inflnence chain mobility in the nanocomposites. 

In-situ intercalation method was reported by Toyota researchers for the synthesis of polyamide nanocomposites that led to the exponential growth in the nanocomposites research. For generation of polymer nanocomposites by this method, the layered silicate mineral is swollen in monomer. After swelling, the polymerization of the monomer is initiated. As monomer is present in and out of the filler interlayers, therefore, the generated stmcture is exfoUated or significantly intercalated. As the rate or mechanism of polymerization in and out of the filler interlayers... 

Another nanofiller type that has been reported to form PAs nanocomposites by in-situ intercalation are CNTs. Gao et al. [64] prepared PA 6-single-wall carbon nanotubes (SWNTs) by in-situ polymerizing caprolactam in the presence of carboxylic acid-functionalized S WNTs (Figure 2.11). They reported an efficient dispersion of the nanofiller in the monomer and a subsequent grafting of the PA 6 chains to the CNTs, through a condensation reaction between the SWNTs carboxyl groups... 

As discussed earlier, the predominant polymerization technique for PA 6.6 formation is the solution-melt process. However, despite the commercial importance of the latter process, few efforts have been reported to expand it on nanocomposites formation by in-situ polymerizing the monomers in the presence of the nanofiller. Notably, although the in-situ intercalation process has been extensively, successfully, and commercially applied for the preparation of lactam/amino acid-based nanocomposites, for example, PA 6, a different picture is presented in diamine-and diacid-based nanocomposites, for example, PA 6.6, mainly characterized by the poor pertinent literature and lack of commercial application. 

To date, the in-situ intercalative polymerization technique is one of the most successful techniques for producing MMT nanocomposites on an industrial scale. The first step of this process, as shown in Figure 6.6, involves the intercalation of a monomer or low-molecular-weight precursor into the galleries of the silicates. 

High impact polystyrene (HIPS) is a blend of PS that has been polymerized in the presence of polybutadiene. This leads to PS chains with grafted polybutadiene, as well as some free PS and PB, and the resultant polymer blend has improved impact strength. HIPS/MMT nanocomposites were formed though in-situ bulk polymerization in the presence of polybutadiene [86]. Intercalated nanocomposites with improved thermal stabihty were formed although the dispersion was different in the PS matrix phase compared to the rubber phase. 

Several methods have been used to obtain polymer nanocomposites by using organoclays [29-32], i.e. solution intercalation [33-39], melt intercalation [40, 41], and in situ interlayer intercalation [30, 42, 43], Among them, in situ interlayer polymerization relies on swelling of... 

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