Influence of the Architecture of Soft Polymer-Functionalized Polymer Nanoparticles on Their Dynamics in Suspension

Abstract

The behavior of nanogels in suspension can be dramatically affected by the grafting of a canopy of end-tethered polymer chains. The architecture of the interfacial layer, defined by the grafting density and length of the polymer chains, is a crucial parameter in defining the conformation and influencing the dynamics of the grafted chains. However, the influence of this architecture when the core substrate is itself soft and mobile is complex; the dynamics of the core influences the dynamics of the tethered chains, and, conversely, the dynamics of the tethered chains can influence the dynamics of the core. Here, poly(styrene) (PS) particles were functionalized with poly(methyl acrylate) (PMA) chains and swollen in a common solvent. NMR relaxation reveals that the confinement influences the mobility of the grafted chain more prominently for densely grafted short chains. The correlation time associated with the relaxation of the PMA increased by more than 20% when the grafting density increased for short chains, but for less than 10% for long chains. This phenomenon is likely due to the steric hindrance created by the close proximity to the rigid core and of the neighboring chains. More interestingly, a thick layer of a densely grafted PMA canopy efficiently increases the local mobility of the PS cores, with a reduction of the correlation time of more than 30%. These results suggest an interplay between the dynamics of the core and the dynamics of the canopy.

Dynamic Mixing Behaviors of Ionically Tethered Polymer Canopy of Nanoscale Hybrid Materials in Fluids of Varying Physical and Chemical Properties

“…The value of λ SF = 3.0 was selected because it was at or above c * in all cases. The T 1 relaxation time probes the speed at which energy is transferred from an excited nucleus to the surrounding environment and has been used as a metric to assess the local, molecular mobility of tethered and untethered polymers. ,,, In contrast to the PFG-NMR results, which measured the polymer motions on a millisecond timescale, the T 1 relaxation time is able to capture the dynamics of the polymers on a nanosecond timescale . For the temperature selected for this particular experiment (i.e., 25 °C), it has been reported that the T 1 relaxation time of tethered polymers is typically shorter than that of free polymers because of the reduced polymer mobility resulting from conformational confinement of tethered polymers when compared to untethered polymers. ,, Similar results were obtained from our 13 C NMR studies.…”

Insights into the Enhanced Oxidative Thermal Stability of Nanoparticle Organic Hybrid Materials Developed for Carbon Capture and Energy Storage

“…The NMR T 1 relaxation time measures the longitudinal relaxation of an excited nucleus and depends upon the local and global surroundings. Throughout the literature, the T 1 relaxation time has been used to assess polymer mobility in various environments, where grafted polymers have been shown to possess shorter relaxation times than untethered polymers as a result of steric confinement. ,− …”

Polymer Adsorbents vs. Functionalized Oxides and Carbons: Particulate Morphology and Textural and SurfaceCharacteristics

“…Therefore, a set of methods could be used in parallel, such as direct (TEM, SEM) and indirect (probe adsorption, SAXS, NMR cryoporometry, DSC thermoporometry, etc.) methods [ 9 , 28 , 31 , 54 , 55 , 56 , 64 , 65 , 66 , 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 111 , 114 , 115 , 116 , 117 , 118 , 119 , 120 , 121 , 122 , 123 , 124 , 125 , 126 , 127 , 128 , 129 , 130 ]. More accurate results can be obtained if several methods are used in parallel (e.g., SAXS and adsorption).…”

“…Therefore, a set of methods could be used in parallel, such as direct (TEM, SEM) and indirect (probe adsorption, SAXS, NMR cryoporometry, DSC thermoporometry, etc.) methods [9,28,31,[54][55][56][64][65][66][74][75][76][77][78][79][80][81][82][83][84][85][86][87]111,[114][115][116][117][118][119][120][121][122][123][124][125][126][127][128][129][130]. More accurate results can be obtained if several methods are used in parallel (e.g., SAXS and adsorption).…”