A5088697107- biodegradable polymer synthesis and properties
- Advanced Polymer Synthesis and Characterization
- Polymer crystallization and properties
- Polymer Nanocomposites and Properties
- Polymer composites and self-healing
- Electrospun Nanofibers in Biomedical Applications
- Block Copolymer Self-Assembly
- Polymer Foaming and Composites
- Polymer Nanocomposite Synthesis and Irradiation
- Intestinal and Peritoneal Adhesions
- Fiber-reinforced polymer composites
- Polymer Surface Interaction Studies
- Synthetic Organic Chemistry Methods
- Surgical Sutures and Adhesives
- Hemostasis and retained surgical items
- Carbon dioxide utilization in catalysis
- Rheology and Fluid Dynamics Studies
University of Minnesota
2017-2024
University of Maryland, College Park
2019
The composition of low-Tg n-butylacrylate-block-(acetoxyaceto)ethyl acrylate block polymers is investigated as a strategy to tune the properties dynamically cross-linked vinylogous urethane vitrimers. As proportion cross-linkable increased, thermorheological properties, structure, and stress relaxation evolve in ways that cannot be explained by increasing cross-link density alone. Evidence presented network connectivity defects such loops dangling ends are increased microphase separation....
Block polymer self-assembly affords a versatile bottom-up strategy to develop materials with the desired properties dictated by specific symmetries and dimensions. Owing distinct compared linear counterparts, bottlebrush block polymers side chains densely grafted on backbone have attracted extensive attention. However, morphologies found in so far are limited, only lamellar cylindrical ordered phases been reported diblock bottlebrushes. The absence of complex morphologies, such as networks,...
Graft block copolymers (BCPs) with poly(4-methyl caprolactone)-block-poly(±-lactide) (P4MCL-PLA) side chains containing 80–100% PLA content were synthesized the aim of producing tough and sustainable plastics. These graft BCPs experience physical aging become brittle over time. For short times, ta, samples are ductile shear yielding is primary deformation mechanism. A double-yield phenomenon emerges at intermediate ta where materials deform by stress whitening followed yielding. At long fail...
A series of model poly((±)-lactide) (PLA) graft copolymers was synthesized by ring-opening metathesis polymerization and used to probe the star-to-bottlebrush transition in shear extensional flows. Ten samples with backbone degrees 11 ≤ Nbb 420 were investigated using small-amplitude oscillatory (SAOS) rheometry measurements. Each contained one PLA side chain length Nsc = 72 per two repeating units on average (graft density z 0.5). The star-like bottlebrush identified at 50–69 SAOS. In...
Graft polymers are useful in a versatile range of material applications. Understanding how changes to the grafted architecture, such as grafting density (z), side-chain degree polymerization (Nsc), and backbone (Nbb), affect polymer properties is critical for accurately tuning performance. For graft-through copolymerizations, Nsc z controlled by macromonomer (NMM) initial fraction feed (fMM0), respectively. We show that these parameters can influence copolymerization reactivity ratios and,...
The order–disorder transitions of diblock copolymers grafted to a common backbone were examined by oscillatory shear rheology and small-angle X-ray scattering. effect grafting density, graft molecular weight, number grafts, dispersity studied using poly[(styrene-alt-N-hydroxyethylmaleimide)-random-(styrene-alt-N-ethylmaleimide)]-graft-poly(4-methylcaprolactone-block-d,l-lactide) [PSHE-g-(P4MCL-PLA)] as model block copolymer. At high densities (25–50%), the temperature (TODT) polymers was...
An H-polymer has an architecture that consists of four branches symmetrically attached to the ends a polymer backbone, similar in shape letter "H". Here, renewable efficiently synthesized using only ring-opening transesterification is demonstrated. The strategy relies on tetrafunctional poly(±-lactide) macroinitiator, from which are grown simultaneously. 1H NMR spectroscopy, size exclusion chromatography (SEC), and matrix-assisted laser desorption/ionization (MALDI) spectrometry were used...
The composition of low-T g n -butylacrylate- block -(acetoxyaceto)ethyl acrylate polymers is investigated as a strategy to tune the properties dynamically cross-linked vinylogous urethane vitrimers. As proportion cross-linkable increased, thermorheological properties, structure, and stress relaxation evolve in ways that cannot be explained by increasing cross-link density alone. Evidence presented network connectivity defects such loops dangling ends are increased microphase separation....
The shear and elongational rheology of graft polymers with poly(norbornene) backbone one poly((±)-lactide) side chain length Nsc = 72 per two repeat units (grafting density z 0.5) was investigated recently by Zografos et al. [Macromolecules 56, 2406-2417 (2023)]. Above the star-to-bottlebrush transition at degrees polymerization Nbb>70, increasing strain hardening observed Nbb, which attributed to side-chain interdigitation resulting in enhanced friction bottlebrush polymers. Here we show...
<p>The composition of low-T<sub>g</sub> <i>n</i>-butylacrylate-<i>block</i>-(acetoxyaceto)ethyl acrylate block polymers is investigated as a strategy to tune the properties dynamically cross-linked vinylogous urethane vitrimers. As proportion cross-linkable increased, thermorheological properties, structure, and stress relaxation evolve in ways that cannot be explained by increasing cross-link density alone. Evidence presented network connectivity...
The composition of low-T g n -butylacrylate- block -(acetoxyaceto)ethyl acrylate polymers is investigated as a strategy to tune the properties dynamically cross-linked vinylogous urethane vitrimers. As proportion cross-linkable increased, thermorheological properties, structure, and stress relaxation evolve in ways that cannot be explained by increasing cross-link density alone. Evidence presented network connectivity defects such loops dangling ends are increased microphase separation....