1) 1,2-Epoxy-3-Chloro Propane (Epichlohydrine, ECH, (Merck)), was distilled (bp 113.0 –113.5°C) from calcium hydride and stored.
2) Dichloromethane (DCM) was washed successively with conc. sulfuric acid, distilled water, 5% aqueous Sodium hydroxide, and distilled and dried over anhydrous calcium chloride. DCM was distilled (bp 40°C) from calcium hydride and stored.
3) Toluene was washed successively with con. sulfuric acid, distilled water, 5% aqueous Sodium hydroxide, and then dried over anhydrous Magnesium sulfates. Toluene was distilled (bp 110°C) and stored.
4) Methanol was used as received.
5) Number-average molecular weight (Mv) and intrinsic viscosity (η) measurements were performed at 35 °C in toluene using a capillary viscometer SEMATECH (VISCOLOGIC TL1). The sample concentration was 1 mg/ml.
6) Gel permeation chromatography (GPC) was performed using a Waters model 200 instrument equipped with a set of four styragel columns (103 Å, 104 Å, 1.5 105 Å and 3.106 Å). The flow rate of tetrahydrofuran was 1 mL/min and the sample concentration was 2 mg/ml. The GPC columns were calibrated using a set of nine narrow-distribution polyethylenoxide standards.
7) The mass loss was measured by Thermogravimetric Analysis (TGA) performed in a nitrogen atmosphere using a Dupont model 9900 thermal analyzer. The heating rate was 20°C min-1.
8) 0.05M, 0.10M, 0.15M, 0.20M, 0.25M, 0.30M and 0.35M sulfuric acid treatment solutions were used to prepare “H-Maghnite 0.05M”, “H-Maghnite 0.10M”, “H-Maghnite 0.15M”, “H-Maghnite 0.20M”,“H-Maghnite 0.25M”,”H-Maghnite 0.30M” and “H-Maghnite 0.35M” respectively. “H-Maghnite XM”, the acid form of “raw-Magnate”, is prepared by shaking the raw material (raw- H-Maghnite) with a solution of sulfuric acid at room temperature until saturation is achieved over a two-day period, The cation-exchanged clay was filtered, resuspended in deionized water continuously until no sulfate ions were detected in the filtrate by BaCl2; isolated by filtration; dried in an oven at 105°C and then finely ground. The clay cation exchange capacity (CEC) was found to be 84 mEq/100g of dried clay.
“Maghnite” and “H-Maghnite” characterization
1) Samples for XRF analysis were prepared using the LiB4O7 fusion method. The resulting beads were analyzed on a Philips PW 2400XRF spectrometer in the Laboratory of Inorganic Chemistry, Granada University, Spain.
2) XRD profiles for pressed powder samples were recorded on a Philips PW 1710 diffractometer using Cu-K α radiation (λ =1.5418 Å).
3) IR absorption spectra were recorded on an ATI Matson FTIR N°9501165 spectrometer using the KBr pressed-disc technique where a 0.5mg sample was added to 300mg KBr and mixed for 3min in a vibratory grinder prior to pressing into a 13mm disc.
4) High-resolution solid-state 29Si and 27Al MAS NMR spectra of untreated (raw-Maghnite) and acid-treated (H-Maghnite0.25M) samples were recorded on a Brüker ASX 500 spectrometer at 59.6 and 130.3 MHz respectively. The sample spinning frequency was 4 KHz for 29 Si and 11.5 KHz for 27Al. Chemical shifts of 27Al are referred to [Al(H2O)6]3+ as external reference.