Real‐time monitoring by proton relaxometry of radical polymerization reactions of acrylamide in aqueous solution

Rodrigues, Elton Jorge da Rocha; Neto, Roberto P.C.; Sebastião, Pedro J.; Tavares, Maria Inês B.

doi:10.1002/pi.5546

Cited by 9 publications

(5 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Subsequent cross-linking of PAM oligomers within the printed object occurred with UV exposure, as illustrated in Figure c. Because polymer chains with terminal, radical moieties exist before cross-linking occurs and persist thereafter for extended durations, − only the ends of PAM chains are cross-linked whereby still longer chains are formed. The final cross-linked hydrogel is illustrated in Figure d.…”

Section: Methodsmentioning

confidence: 99%

Plasmonic Metamaterial Gels with Spatially Patterned Orientational Order via 3D Printing

et al. 2019

View full text Add to dashboard Cite

Optical properties can be programmed on mesoscopic scales by patterning host materials while ordering their nanoparticle inclusions. While liquid crystals are often used to define the ordering of nanoparticles dispersed within them, this approach is typically limited to liquid crystals confined in classic geometries. In this work, the orientational order that liquid crystalline colloidal hosts impose on anisotropic nanoparticle inclusions is combined with an additive manufacturing method that enables engineered, macroscopic three-dimensional (3D) patterns of co-aligned gold nanorods and cellulose nanocrystals. These gels exhibit polarization-dependent plasmonic properties that emerge from the unique interaction between the host medium’s anisotropic optical properties defined by orientationally ordered cellulose nanocrystals, from the liquid crystal’s gold nanorod inclusions, and from the complexity of spatial patterns accessed with 3D printing. The gels’ optical properties that are defined by the interplay of these effects are tuned by controlling the gels’ order, which is tuned by adjusting the gels’ cellulose nanocrystal concentrations. Lithe optical responsiveness of these composite gels to polarized radiation may enable unique technological applications like polarization-sensitive optical elements.

show abstract

Section: Methodsmentioning

confidence: 99%

Plasmonic Metamaterial Gels with Spatially Patterned Orientational Order via 3D Printing

et al. 2019

View full text Add to dashboard Cite

show abstract

“…The evolution of the magnetic relaxation domain curves in TD-NMR as a function of time can be represented through contour surface maps (Rodrigues et al 2018). The intensities and relaxation time values of the domains at each moment represent the dynamics of the water evaporating inside the bamboo cavities as a function of time.…”

Section: Table 3 Fluid's Total Mass In Saturated Bamboo Samplesmentioning

confidence: 99%

An investigation of the fluid-holding cavities in a lignocellulose-based bamboo matrix via a combined X-ray microtomography and proton time-domain NMR approach

Rodrigues

Neto

Alves

et al. 2023

Preprint

Self Cite

View full text Add to dashboard Cite

Bamboo (Dendrocalamus giganteus) is a functionally graded material with well-organized hierarchical structures. Its micrometer-sized vascular bundles and parenchymatic living cells allow an efficient upward flow of water and nutrients, endowing the organism with remarkably fast growth. As demonstrated recently, the hollow microstructure channels can be explored as a natural template for microfluidics applications in chemical synthesis, analytical detection, solar steam generation, and electrochemical devices. Thus, the knowledge of the kinetics of the imbibition and spatial distribution of fluid through the microcavities of the bamboo vegetal tissue became of interest. Here, we employed a combination of X-ray microtomography (µCT) and proton time-domain NMR (TD-NMR) to identify, measure, and investigate empty volumes embedded in the bamboo's tissue as experienced by different organic and inorganic fluids, namely dimethyl sulfoxide (DMSO) and distilled water (H2O). Results have shown that the extensive communication between the voids (parenchymal cells and vascular channels) does not prevent the individuation of fluid reservoirs with different behaviors, as evidenced by the H2O desorption profile. Bamboo parenchyma was the tissue that retained more residual H2O after desorption. The difference in wettability of bamboo tissues by DMSO and H2O was detected.

show abstract

“…The standard T 1 and T 2 methods (inversion-recovery and CPMG) require the use of two separated reaction samples that are not ideal, as the two reactions did not have the exact same rates. Rodrigues et al [28,29] applied CWFP sequences to real-time monitoring of the polymerization crosslinking reaction of acrylamide-based hydrogels. The CP-CWFP results showed high sensitivity and time resolution when monitoring important parameters of radical polymerization.…”

Section: Polymersmentioning

confidence: 99%

“…The CP-CWFP results showed high sensitivity and time resolution when monitoring important parameters of radical polymerization. Rodrigues et al [29] used CP-CWFP to study the polymerization of acrylamide using a redox-pair initiator system. They observed that T 1 was more sensitive than T 2 when monitoring the reaction, confirming it is a good probe to monitor monomer conversion in real time in an automated non-destructive fashion.…”

Section: Polymersmentioning

confidence: 99%

“…All the proprieties of CWFP methods make them an important tool for industrial protocols, as well as in quantitative analysis where CWFP can enhance the SNR compared with conventional CPMG or FID protocols [14][15][16][17][18][19][20][21][22].In this review, we outline SSFP/CWFP theory and their applications in low field TD-NMR to enhance SNR, in quantitative analyses, in flow analyses, in thermal diffusivity measurements, for fast simultaneous measurements of T 1 and T 2, , and in the fast T 1 method. CWFP methods have been applied in many conventional TD-NMR spectrometers, such as the Minispec mq20, Bruker (0.47 T) [23], Maran Ultra (0.54 T) [24], SLK-100, SpinLock (0.28 T) [25,26], Tecmag spectrometer [27], and Oxford instrumentations [28,29]. The complete ExpSpel code used to implement the CWFP pulse sequence in the Minisepc mq20 spectrometer, Bruker (NF electronics) is available in the Supplementary Materials.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Applications of Continuous Wave Free Precession Sequences in Low-Field, Time-Domain NMR

2019

View full text Add to dashboard Cite

This review discusses the theory and applications of the Continuous Wave Free Precession (CWFP) sequence in low-field, time-domain nuclear magnetic resonance (TD-NMR). CWFP is a special case of the Steady State Free Precession (SSFP) regime that is obtained when a train of radiofrequency pulses, separated by a time interval T p shorter than the effective transverse relaxation time (T 2 *), is applied to a sample. Unlike regular pulsed experiments, in the CWFP regime, the amplitude is not dependent on T 1 . Therefore, T p should be as short as possible (limited by hardware). For T p < 0.5 ms, thousands of scans can be performed per second, and the signal to noise ratio can be enhanced by more than one order of magnitude. The amplitude of the CWFP signal is dependent on T 1 /T 2 ; therefore, it can be used in quantitative analyses for samples with a similar relaxation ratio. The time constant to reach the CWFP regime (T*) is also dependent on relaxation times and flip angle (θ). Therefore, T* has been used as a single shot experiment to measure T 1 using a low flip angle (5 • ) or T 2 , using θ = 180 • . For measuring T 1 and T 2 simultaneously in a single experiment, it is necessary to use θ = 90 • , the values of T* and M 0 , and the magnitude of CWFP signal |M ss |. Therefore, CWFP is an important sequence for TD-NMR, being an alternative to the Carr-Purcell-Meiboom-Gill sequence, which depends only on T 2 . The use of CWFP for the improvement of the signal to noise ratio in quantitative and qualitative analyses and in relaxation measurements are presented and discussed.to suppress these anomalies using a small variation of T p that cancels the echo component. In the same year, Schwenk [4] proposed the Quadriga Fourier Transform (QFT) to suppress these anomalies. The QFT method was based on a small variation in frequency offset. Although these procedures minimize these anomalies, SSFP sequences were not routinely used in high resolution NMR.We revised these methods and suggested some modifications to increase the applications of SSFP in high-resolution NMR using the Traff apodization function [5] to minimize the truncation problem, or processing the SSFP time domain signal with a parametric method based on Krylov Basis Diagonalization Method (KBDM) [6]. KBDM solves the truncation and phase anomalies but not the amplitude problem. Therefore, SSFP sequences cannot be used to efficiently enhance signal to noise ratio (SNR) in high-resolution NMR. SSFP sequences have been successfully used in magnetic resonance imaging [7,8] and in low-field, time-domain NMR [9][10][11]. The use of a SSFP sequence in low field time domain (TD-NMR) started in year 2000 [12,13]. The applications of SSFP sequences in TD-NMR can be performed under the drastic condition where T p < 1 ms. Under this condition, a truly continuous wave free precession (CWFP) regime is obtained [13]. Normally, CWFP sequences use T p < 0.5 ms, as T p has to be shorter than T 2 *, which is in the order of 1 ms in most TD-NMR spectrometers.In the CWFP regime, F...

show abstract

Real‐time monitoring by proton relaxometry of radical polymerization reactions of acrylamide in aqueous solution

Cited by 9 publications

References 33 publications

Plasmonic Metamaterial Gels with Spatially Patterned Orientational Order via 3D Printing

Plasmonic Metamaterial Gels with Spatially Patterned Orientational Order via 3D Printing

An investigation of the fluid-holding cavities in a lignocellulose-based bamboo matrix via a combined X-ray microtomography and proton time-domain NMR approach

Applications of Continuous Wave Free Precession Sequences in Low-Field, Time-Domain NMR

Contact Info

Product

Resources

About