A5061863785- Polymer crystallization and properties
- Polymer Nanocomposites and Properties
- biodegradable polymer synthesis and properties
- Material Dynamics and Properties
- Force Microscopy Techniques and Applications
- Lignin and Wood Chemistry
- Polymer Surface Interaction Studies
- Adsorption, diffusion, and thermodynamic properties of materials
- Advanced Cellulose Research Studies
- Advanced Theoretical and Applied Studies in Material Sciences and Geometry
Columbia University
2020-2022
We explore the role of nanoparticle (NP) size and loading on kinetics polymer crystallization, in particular, crystal growth rate (G), under conditions where NPs polymers are uniformly mixed. While there significant differences with variations NP loading, measured G data fall into an apparently universal curve when we consider them basis confinement. In find that ratio volume, VPEO, to surface area, SANP, is most appropriate confinement metric 10–100 nm range, which includes typical lamellar...
We systematically examine the role of self-assembly state polymer-grafted silica nanoparticles (GNPs) on spherulitic growth kinetics a poly(ethylene oxide) (PEO) matrix. The (NPs) are functionalized with either unimodal or bimodal polymer brushes to control their within semicrystalline In former case, we employ poly(methyl methacrylate) (PMMA) brush (miscible PEO), while latter has short dense polystyrene (PS carpet) brush, which is immiscible PEO matrix, and long, sparse PMMA brush. GNPs...
It has recently been established that polymer crystallization can preferentially place nanoparticles (NPs) into the amorphous domains of a lamellar semicrystalline morphology. The phenomenology this process is clear: when time for NP diffusion shorter than crystal growth time, then NPs are rejected by growing crystals and placed in domains. However, since there no quantitative characterization ordered state, we develop correlation function analysis small-angle X-ray scattering data, inspired...
We present in situ tracking of silica nanoparticle (NP) migration from a poly(ethylene oxide) (PEO) melt into interlamellar region using atomic force microscopy (AFM). Our results confirm the previous hypothesis that NPs migrate regions at crystallization growth rates smaller than critical value under isothermal conditions. Under these slow conditions, bare are rejected as defects by growing crystal PEO, and imaging on large (50 nm) helps track amorphous zones. extend this AFM technique to...
We have previously shown that semicrystalline polymers can be reinforced by adding nanoparticles (NPs) and then ordering them into specific motifs using the crystallization process. A key result we found is when spherulite growth rate slowed below a critical value, then, NPs order amorphous interlamellar regions of structure. The effects in this context been examined, here focus on role NP diffusivity. achieve goal changing poly(ethylene oxide) (PEO) molecular weight as route to altering...
The effect of lignin nanoparticles (LNPs) on the crystallization kinetics poly(ethylene oxide) (PEO) is examined. Lignin from spruce and ionic isolation was used to prepare LNPs with a number-averaged diameter 85 nm (with relatively large polydispersity) by an ultrasonication method. PEO-based nanocomposites four different LNP contents (5, 10, 15, 20 wt %) were prepared subject isothermal nonisothermal protocols in series experiments. Scanning electron microscopy (SEM) images showed...
We systematically investigate the effects of adding ungrafted PMMA versus silica-grafted (PMMA-g-SiO2) on crystallization kinetics and mechanical properties PEO. In grafted analogue, chains were grown from surface 14 nm diameter silica nanoparticles at a grafting density ∼0.42 chain/nm2. The molecular weight was varied (20–85 kDa), extent confinement regulated by varying PEO fraction. While crystallinity crystal growth rate in systems track each other, exhibit enhanced kinetics, most likely...