Aminolauric acid

Nylon-6. Nylon-6—clay nanometer composites using montmorillonite clay intercalated with 12-aminolauric acid have been produced (37,38). When mixed with S-caprolactam and polymerized at 100°C for 30 min, a nylon clay—hybrid (NCH) was produced. Transmission electron microscopy (tern) and x-ray diffraction of the NCH confirm both the intercalation and molecular level of mixing between the two phases. The benefits of such materials over ordinary nylon-6 or nonmolecularly mixed, clay-reinforced nylon-6 include increased heat distortion temperature, elastic modulus, tensile strength, and dynamic elastic modulus throughout the —150 to 250°C temperature range. 

Table 20 presents the results pertaining to the synthesis and properties of the gels. The gels are seen to sorb heparin from plasma solution. Their capacity (the maximal amount of heparin sorbed) increases as the mobility and accessibility of the cholesterol fragment for the macromolecules of heparin is increased by varying the length of the polymethylene spacer. The data in Table 20 illustrate that the capacity varies from 0.7 to 0.9 and 1.3 mg/mg of immobilized UChD for cholesterol esters of N-meth-acryloyl-fS-alanine (n — 2), N-acryloyl-co-aminoenantic acid (n = 6), and N-meth-acryloyl-co-aminolauric acid (n = 11), respectively. 

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. 

The modified montmorillonite prepared by cation exchange reaction with 12-aminolauric acid can chemically react with caprolactum molecules and makes the caprolactum polymer chain ends tethered to the silicate layers through the 12-aminolauric acid [41-42]. A. similar method has been used to prepare polyamide-6 nanocomposites [8,43-46]. 

Nylon 12 has only one monomer, aminolauric acid. It has the necessary amine group on one end, and the acid group on the other. It polymerizes with itself to produce the polyamide containing 12 carbons between the two nitrogen atoms of the two amide groups. Its structure is shown in Figure 6.53. 

In this work, the more successful preparation route involved mixing 12-aminolauric acid-modified montmoriUonite (12-MMT) with e-caprolactam, and the mixture was heated at 250-270 °C for 48 h. Depending on the amount of 12-MMT introduced, either exfohated (for less than 15 wt%) or intercalated structures (from 15 to 70wt%) were obtained, as evidenced by X-ray diffraction (XRD) and... 

Messersmith and Giannelis [20] also reported the preparation of nanocomposites by reacting protonated 12-aminolauric acid-exchanged montmorillonite with e-caprolactone monomer. The monomer ring was initially intercalated in the gaps... 

The nylon-clay nanocomposites were prepared by in situ polymerization in the presence of organically modified, with aminolauric acid, montmorillonite. The reaction between nylon monomer and modified montmorillonite rendered nylon chains end-tethered though aminolauric acid to the silicate surface leading to exfoliated silicates (61). However, not all polymer nanocomposite systems could be produced via in situ polymerization processes because of the chemical sensitivity of polymerization catalysts. Direct melt blending of hydrophilic polymers with montmorillonite in its pristine state or polymers with surfactant-intercalated montmorillonite was found to be possible to deliver polymer intercalated or exfoliated nanocomposites (62,63). 

For other polyamide/clay nanocomposites, PA 11/OMMT nanocomposites were prepared by Zhang, Yu, and Fu [30] via in situ intercalative polymerization. The polymerization involved two steps first the cation exchange of MMT with 11-aminolauric acid, and then the polymerization of 11-aminolauric acid in the presence of OMMT. The crystallization rate of the PA 11 matrix was obviously improved by the nanoscale-dispersed MMT clay. A similar in situ polymerization of exfoliated PAll/MMT nanocomposites containing different amounts of MMT was performed by Yang and co-workers [31]. First, 11-aminoundecanoic acid was mixed with organoclay in a vessel, and then the mixtures were heated to 100-150 °C to drive off the water and heated again to 230-260 °C for 4 h to achieve polymerization. 

Ma and co-workers [38] have investigated this method in attempts to prepare nanocomposites with PA 6-based polymer. These nanocomposites were filled with OMMT modified by three different swelling agents, namely, n-dodecylamine, 12-aminolauric acid, and 1,12-diaminodecane. Upon treatment, the interlayer spacing of the OMMT was increased. In order to obtain the PA 6-based nanocomposites, the PA 6 was dissolved in formic acid in the presence of different amounts of OMMT. After deposition in deionized water, the nanocomposites were recovered in a vacuum at 40 °C for 24 h. 

The second article [14] describes the in situ preparation of the nylon-montmorillonite polymer nanocomposite from the 12-aminolauric acid exchanged montmorillonite prepared in the previous article. The montmorillonite content in the polymerization varied from 1.5% to 59.6%. The general procedure was to melt -caprolactam, the organomontmorillonite prepared with 12-aminolauric acid, and 6-aminocaproic acid together with stirring at 100 °C for 30 min. The 6-aminocaproic... 

A second series of two articles was published by Toyota Research in the same year, 1993, in the Journal of Polymer Science Part A Polymer Chemistry. The first article [23] was similar in theme to the above work published in Journal of Materials Research. The montmorillonite was intercalated with -caprolactam in an aqueous HCl solution. This orga-nomontmorillonite was treated in the same way as the 12-aminolauric acid-exchanged montmorillonite in the above work by blending it with e-caprolactam and aminocaproic acid and producing the polymer nanocomposite at 160 °C for 6h. The montmorillonite content varied from 1.9% to 7.1%. The Young s modulus and heat distortion temperature of... 

A sixth article on modulus performance of nylon 6-clay nanocomposites was also published in 1995 in the Journal of Applied Polymer Science [25] by Toyota Research. The Young s modulus of nylon 6-clay nanocomposites was prepared with montmorillonite, saponite, a synthetic hectorite (Laponite RD), and synthetic mica. The in situ polymerization procedure with 12-aminolauric acid exchanged onto the minerals was utilized to prepare the nylon 6 nanocomposites. The montmorillonite polymer nanocomposite has the largest modulus, followed by mica, saponite, and, the lowest value, Laponite RD. 

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