Comprehensive Analysis of Oxidized Waxes by Solvent and Thermal Gradient Interaction Chromatography and Two-Dimensional Liquid Chromatography

Transcription

1 Supporting Information Comprehensive Analysis of Oxidized Waxes by Solvent and Thermal Gradient Interaction Chromatography and Two-Dimensional Liquid Chromatography Anthony Ndiripo, Harald Pasch* Department of Chemistry and Polymer Science, University of Stellenbosch, 7602 Matieland, South Africa *Corresponding author: Prof. Harald Pasch, Table of Contents 1. Detailed description of the size exclusion chromatography (SEC), Fourier-transform Infrared spectroscopy (FTIR), differential scanning calorimetry method (DSC) as well as crystallization analysis fractionation (CRYSTAF) experimental methods. 2. Diagram of temperature profile and flow rate used in TGIC, 3. Bulk analyses of the three waxes by DSC, CRYSTAF and SEC. 4. ATR-FTIR spectra of waxes No. 1, 2 and 3, 5. Tabular information for the peak elution volumes and peak areas of wax No. 3 as influenced by column temperature. 6. HT-SGIC-FTIR and HT-TGIC-FTIR analysis of wax No. 3. S-1

2 Supplementary Experimental methods Size Exclusion Chromatography (SEC). Molar masses and molar mass dispersities of the wax samples were determined on a PL-GPC 220 High Temperature Chromatograph [Polymer Laboratories, Church Stretton, UK (now part of Agilent)] equipped with a differential refractive index (RI) detector. The samples (4 mg) were dissolved in 2 ml of TCB for 0.5 hr together with % butyl-hydroxy-toluene (BHT) which acted as a stabilizer to prevent sample oxidative decomposition/degradation. TCB with % BHT was used as the mobile phase at a flow rate of 1 ml min -1. Three mm 2 PLgel Olexis columns (Agilent Technologies, UK) were used together with a mm 2 PLgel Olexis guard column and 200 μl of each sample was injected. All experiments in HT-SEC were carried out at 150 C. Fourier Transform Infrared Spectroscopy (FTIR). Attenuated total reflectance (ATR) measurements of the waxes and their fractions were recorded on a Thermo Nicolet is10 spectrometer. Solid samples were used in all the analyses with no prior modifications (except drying in the case of fractions). Spectra recorded from 4000 to 650 cm -1 were obtained from a collection of 64 scans at a resolution of 4 cm -1 with automatic background subtraction. Thermo Scientific OMNIC software (version 8.1) was used for data collection and processing. Differential Scanning calorimetry. The wax samples were analyzed using the Q100 DSC system (TA Instruments, Delaware, USA) at a heating and cooling rate of 10 C min -1 across a temperature range of C. An aluminum pan and lid folded and pressed were used as a reference and approximately 5 mg of each sample were used. Crystallization Analysis Fractionation (CRYSTAF). A commercial CRYSTAF apparatus Model 200 (PolymerChAR, Valencia, Spain) was used for crystallization analysis S-2

3 Differential distribution (dc/dt) Temperature [ C] Flow rate [ml/min] fractionation experiments. Approximately 20 mg of each sample were dissolved in 35 ml of TCB. Crystallization was carried out under constant stirring in stainless steel reactors which are equipped with automatic agitation and filtration devices. The samples were dissolved for 90 min. After dissolution, the temperature was decreased from 100 C to approximately 30 C at a rate of 0.2 C min -1. The concentration of the solution was determined automatically using an infrared detector operating at a fixed wavelength of 3.5 μm. Five samples were analyzed simultaneously and the experiment took approximately 15 hrs. Injection Cooling process Elution process Time [min] Figure S1. Temperature profile (black line with red spheres) and flow rate (blue line with triangles) used in TGIC. a Soluble fraction b Exo UP Heat Flow [Wg -1 ] C 92.6 C C 44.5 C Crystallization temperature [ C] C 94.2 C C C C 92.2 C C Temperature [ C] S-3

4 Absorbance [-] dw/dlog M c BHT peak Log M Figure S2. CRYSTAF profiles of waxes No. 1, 2 and 3, solvent: 1,2-dichlorobenzene, cooling rate 0.2 C min -1 (a); DSC thermograms showing first crystallization and second melting curves, heating and cooling rates 10 min -1 (b); SEC molar mass distribution curves (c). Insert No. 1 No. 2 No Wavenumber [cm -1 ] Figure S3. Overlays of ATR-FTIR spectra of waxes No. 1, 2 and 3 and enlargement of the carbonyl regions. S-4

5 Table S1. Peak elution volumes of wax No. 3 as influenced by column temperature. Column temperature [ C] V e [ml] Peak 1 Peak 2 Peak 3 Peak 4 Peak Table S2. Peak areas of wax No. 3 as influenced by the column temperature. Column temperature [ C] Area % Peak 1 Peak 2 Peak 3 Peak 4 Peak S-5

6 Table S3. Peak area comparisons of waxes No. 1, 2 and 3. *Saturated detector signal Elution volume [ml] Rotation time [min] Elution volume [ml] Hydroxyl group absorbances Carbonyl absorbances Wavenumber [cm -1 ] Figure S4. 2D contour plot of HT-SGIC-FTIR analysis of wax No. 3. FTIR was coupled to HPLC via the LC-transform interface Elution Time [min] Rotation time [min] Wavenumber [cm -1 ] Methyl stretches indicate location of low molar mass oligomers Figure S5. 2D contour plot of HT-TGIC-FTIR analysis of wax No. 3. FTIR was coupled to HPLC via the LC-transform interface. S-6

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