Polymer structure and conformational dynamics are essential to polymer macroscopic properties, but are challenging to probe. We report here a synthetic pathway to chemically add a nitroxide moiety onto block polymers in a mild, aqueous environment and demonstrate its use in a series of polymeric micelles using Electron Paramagnetic Resonance (EPR) spectroscopy. The micelles were characterized with several analytical approaches and EPR findings were in general consistent with other approaches. Upon exposure to organic solvents, the line shape changes reflected the micelle swelling and EPR spectral simulations revealed structural information of the swelled micelles. The label introduced via our method can be cleaved and replaced with other probes to report different information site‐specifically. The mild conditions facilitate the future use of EPR in solving biopolymer problems. In combination with other labeling approaches, one can perform polymer spin labeling with different chemistry, so that various information about polymers can be obtained site‐specifically. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys.
Polymers with multiple tunable responses were achieved by incorporating boronic acid functionality along the backbone of a thermoresponsive polymer. The inherent Lewis acidity and diol‐sensitivity of boronic acid moieties allowed these polymers to respond to changes in pH and glucose concentration. Through reversible addition‐fragmentation chain transfer copolymerization of boronic acid‐containing monomers with
- PAR ID:
- 10041066
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Journal of Polymer Science Part A: Polymer Chemistry
- Volume:
- 55
- Issue:
- 14
- ISSN:
- 0887-624X
- Format(s):
- Medium: X Size: p. 2309-2317
- Size(s):
- p. 2309-2317
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
ABSTRACT 2017 ,55 , 1770–1782 -
more » « less
ABSTRACT Carbohydrates are the fundamental building blocks of many natural polymers, their wide bioavailability, high chemical functionality, and stereochemical diversity make them attractive starting materials for the development of new synthetic polymers. In this work, one such carbohydrate,
d ‐glucopyranoside, was utilized to produce a hydrophobic five‐membered cyclic carbonate monomer to afford sugar‐based amphiphilic copolymers and block copolymers via organocatalyzed ring‐opening polymerizations with 4‐methylbenzyl alcohol and methoxy poly(ethylene glycol) as initiator and macroinitiator, respectively. To modulate the amphiphilicities of these polymers acidic benzylidene cleavage reactions were performed to deprotect the sugar repeat units and present hydrophilic hydroxyl side chain groups. Assembly of the polymers under aqueous conditions revealed interesting morphological differences, based on the polymer molar mass and repeat unit composition. The initial polymers, prior to the removal of the benzylidenes, underwent a morphological change from micelles to vesicles as the sugar block length was increased, causing a decrease in the hydrophilic–hydrophobic ratio. Deprotection of the sugar block increased the hydrophilicity and gave micellar morphologies. This tunable polymeric platform holds promise for the production of advanced materials for implementation in a diverse range of applications. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem.2019 ,57 , 432–440 -
more » « less
ABSTRACT The polymerization of biorenewable molecules to polymers with hydrolyzable main‐chain functionality is one approach to identifying sustainable replacements for common, environmentally unsound packaging plastics. Bioaromatic polyacetals were synthesized via acid‐catalyzed acetal formation from dialdehydes and tetraols. Ethylene linked dialdehyde monomers
VV andSS were constructed from bioaromatics vanillin and syringaldehyde, respectively. Tetraol monomers included biogenic erythritol (E ), along with pentaerythritol (P ), and ditrimethylolpropane (D ). Four copolymer series were prepared with varying tetraol content:E /P ‐VV ;E /D ‐VV ;E /P ‐SS ; andE /D ‐SS . Number average molecular weights (Mn ) ranged from 1,400 to 27,100 Da. Generally, the copolymerization yields were inversely proportional to the feed fraction of erythritol (E ), implying that tetraolsP andD react more readily. The materials were typically amorphous and exhibited glass transition temperatures (Tg ) ranging from 57 to 159 °C, suitably mimicking theTg values of several commodity plastics. The syringaldehyde‐based copolymers exhibited a higherTg range (71–159 °C) than the vanillin‐based copolymers (57–110 °C). Accelerated degradation studies in aqueous HCl (3M , 6M , concentrated) over 24 h showed that degradation (Mn decrease) was proportional to the acid concentration. A one‐year degradation study ofE 50/D 50‐SS (from 50% feed of erythritol) in seawater, deionized water, tap water, or pH 5 buffer showed noMn decrease; but in pH 1 buffer, the decrease was 40% (18,800 to 11,200). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2016 ,133 , 44089. -
more » « less
ABSTRACT Glycohydrogels containing 2′‐acrylamidoethyl‐β‐
d ‐galactopyranoside and varying levels ofN ,N ′ methylene bisacrylamide and 3‐acrylamidopropyltris(trimethylsiloxy)silane were synthesized to determine the effects of crosslinker and amphipathic balance on equilibrium water content (EWC), bound water population, and hydrogen bonding dynamics at the water–polymer interface. Analogous dimethylacrylamide hydrogels were synthesized for comparison with a system containing lower hydrogen bonding propensity. An approach combining experiment (proton nuclear magnetic resonance, thermogravimetric analysis, differential scanning calorimetry, and dynamic vapor sorption analysis) and molecular dynamics simulations was employed to examine the relationship between bulk hydrogel properties, molecular water mobility, and hydrogen bonding characteristics. It was found that copolymer composition (hydrophobic content) and crosslink concentration in high water content glycohydrogels affect EWC, and by extension, structural water population. The organization of water at the polymer interface is greatly impacted by the surrounding environment, where hindered molecular water mobility promotes water–polymer binding and decreases water–water clustering. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys.2019 ,57 , 584–597 -
more » « less
ABSTRACT New methacrylate monomers with carbazole moieties as pendant groups were synthesized by multistep syntheses starting from carbazoles with biphenyl substituents in the aromatic ring. The corresponding polymers were prepared using a free‐radical polymerization. The novel polymers contain
N ‐alkylated carbazoles mono‐ or bi‐substituted with biphenyl groups in the aromatic ring.N ‐alkyl chains in polymers vary by length and structure. All new polymers were synthesized to evaluate the structural changes in terms of their effect on the energy profile, thermal, dielectric, and photophysical properties when compared to the parent polymer poly(2‐(9H‐carbazol‐9‐yl)ethyl methacrylate). According to the obtained results, these compounds may be well suited for memory resistor devices. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem.2019 , 57, 70–76
