Abstract:

The generation of linear control of un-grafted poly(caprolactone) (PCL), poly[oligo(ethylene glycol) methyl methacrylate mono-methyl ether] (POEGMA) generated in situ will help us understand the reaction conditions needed to successfully graft these polymers onto the surface of SiO2 nanoparticles. Thermogravimetric analysis (TGA) & Fourier Transform Infrared Spectroscopy (FTIR) data were collected and directly compared to the grafted species, when these grafted species were generated, to confirm the presence of these polymers on the surface of the NPs. Gel permeation chromatography (GPC) & nuclear magnetic resonance (NMR) were performed to analyze the structure of these linear analogues and give kinetic time points for controlling the block length of PCL & POEGMA respectively.

Suggested Citation:

Keller, Christopher. 2020. Thermogravimetric analysis, infrared analysis, and nuclear magnetic resonance of linear un-grafted PCL, and POEGMA controls generated in situ during surface reactions with variances in block length. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/n7-eqja-qv32

Publications:

Keller, C. B., Walley, S. E., Jarand, C. W., He, J., Ejaz, M., Savin, D. A., & Grayson, S. M. (2021). Synthesis of poly(caprolactone)-block-poly[oligo(ethylene glycol)methyl methacrylate] amphiphilic grafted nanoparticles (AGNs) as improved oil dispersants. Polymer Chemistry, 12(33), 4758–4769. doi:10.1039/d1py00418b

Purpose:

To track the conversion of monomers to polymer during grafting reactions. Un-grafted polymers can be easily isolated and studied for direct comparison to grafted species.

Data Parameters and Units:

Nuclear Magnetic Resonance (NMR) is presented in the form of arbitrary intensity (a.i.) vs chemical shift (ppm). FTIR is presented in the form Abs (a.i.) vs wavenumbers (reciprocal cm). TGA is presented in the form of % weight loss vs. Temperature (degrees C). GPC is presented in change in refractive index (r.i. in mV) vs retention time (minutes).

Methods:

Nuclear Magnetic Resonance (NMR) measurements, proton (1H) and carbon (13C), were collected in deuterated chloroform (CDCl3) for the free, un-grafted PCL samples & deuterated methanol (MeOD) for the free, un-grafted POEGMA samples. Samples for 1H NMR measurements were made up at a concentration of 10 mg/mL with sufficient scans taken at 5 sec of relaxation time and 298K to achieve acceptable signal to noise. Samples for 13C NMR measurements made up at a concentration of 50 mg/mL with sufficient scans taken at 5 sec of relaxation time and 298K to achieve acceptable signal to noise. GPC data runs were performed with an injection load of 50 μL for 45 min at 1 mL/min purge flow rate, at a sample concentration of 4 mg/mL in tetrahydrofuran (THF) after being filtered through a Whatman 0.45 μm filter. Measurements are presented in the form of mV with respect to retention time in minutes. Molecular weight & dispersity measurements were calculated from integration of the peak of increased RI (mV) with respect to retention time. Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) measurements were collected with a background consisting of 32 scans immediately prior to each sample. Measurements were conducted with 3 mg of sample over 64 repetitive scans. Data is presented in the form of wavenumbers (cm-1) to arbitrary absorbance intensity from 400 to 4000 cm-1 wavenumbers. Fourier Transform Infrared Spectroscopy (FTIR) measurements were collected with samples were made up into potassium bromide (KBr) pellets at a concentration of 5 mg of sample per 100 mg of KBr. The mixture was ground via mortar and pestle and dried under high vacuum. A background consisting of 32 scans was collected immediately prior to each sample. Samples were placed in an inert nitrogen chamber and allowed to equilibrate for 5 minutes before collecting measurements. Measurements were collected in absorbance over 64 scans. Data is presented in the form of wavenumbers (cm-1) to arbitrary absorbance intensity from 400 to 4000 cm-1 wavenumbers. Thermogravimetric Analysis (TGA) data was collected in a tared 100 μL platinum sample pan, ramping from 25˚C to 600˚C at a rate of 5 ˚C/min under inert nitrogen atmosphere (10 mL/min), following by isothermal hold at 600 ˚C for 30 min. For the case of the nanoparticles dispersed in deionized water, and those that have been dispersed in deionized water exposed to oil, samples were ramped 5˚C/min from 25˚C to 100˚C in inert nitrogen atmosphere (10 mL/min) and held at a 100˚C for 5 min isothermally to remove all water presence, followed by collection from 100˚C to 500˚C at a ramp rate 10˚C/min in an “air” (10 mL/min) atmosphere. Measurements are presented in the form of percent weight loss over a range of temperatures (˚C).

Instruments:

Nuclear Magnetic Resonance (NMR) measurements, proton (1H) and carbon (13C), were collected on a Bruker Avance 300 MHz instrument. GPC data was collected with a Waters 1515 isocratic high-performance liquid chromatography (HPLC) pump, and Waters 2414 refractive index (RI) detector with three PSS SDV analytical 500 Å (8 x 300 mm) columns in series (Polymer Laboratories Inc.). Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) measurements were collected on an Thermo Scientific Nicolet iS50. The iS50 FTIR was equipped with a DTGS-ATR detector, diamond crystal, and XT-KBr beamsplitter. Instrument parameters were set to a gain of 1 arbitrary units (a.u.), data spacing 0.482 cm-1, resolution 4 cm-1, absorbance format, optical velocity of 0.4747 a.u., and aperture size of 100. Fourier Transform Infrared Spectroscopy (FTIR) measurements were collected on a Thermo Nicholet NEXUS 670 FTIR. Thermogravimetric Analysis (TGA) was completed on a Thermo Scientific Q500.

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