Thermal degradation of poly(ethylene oxide) and polyacrylamide with ascorbic acid

Vijayalakshmi, S.; Raichur, Ashok M.; Madras, Giridhar

doi:10.1002/app.24115

Cited by 12 publications

(5 citation statements)

References 17 publications

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“…In the absence of oxygen removal from the hydrogel solutions prior to catalyst addition, we observed significant PEO degradation (verified with SEC, data not shown). This is in accordance with reports by the Madras and Crowley groups who observed similar degradation phenomena. Hydrogel samples were left in the catalyst solution for 24 h prior to removal, followed by sequential self-dialysis (osmotic driving force provided by concentration gradient between the hydrogel interior and exterior) against fresh DI solutions to remove residual catalyst.…”

Section: Resultssupporting

confidence: 94%

Dangling-End Double Networks: Tapping Hidden Toughness in Highly Swollen Thermoplastic Elastomer Hydrogels

et al. 2016

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This report introduces a unique method of significantly improving toughness in highly swollen block copolymer-based thermoplastic elastomer (TPE) hydrogels by converting an intrinsically large population of dangling chain ends into a mechanically active second network. In one form, the TPE hydrogels developed by our group are based on swelling of a vitrified melt-blend of two amphiphilic block copolymer species, sphere-forming polystyrene-poly(ethylene oxide) (SO-H) diblock and triblock (SOS) copolymers. Here, the PEO midblock in the SOS triblock copolymer serves to tether adjacent PS spherical aggregates, producing hydrogel networks that are incredibly elastic and mechanically robust, preserving their shape even at the very high intrinsic swelling ratios produced at low SOS concentrations (e.g, 37 g of H2O/(g of polymer) at 3.3 mol % SOS). In this report, we advance the utility of this framework by exploiting the hundreds of dangling PEO chain ends per spherical aggregate to form a second, mechanically active network. The approach is based on a stepwise installation of two tethering SOS triblock copolymer populations. The first is present directly during melt-state self-assembly of the original diblock/triblock copolymer blend and inherently determines the equilibrium swelling ratio of resulting hydrogel. The second population is then introduced postswelling, by simply coupling the dangling SO diblock copolymer chain ends under conditions largely free of the mechanical stress osmotically imposed on the primary network. Notably, this action simply shifts the ratio of diblock and triblock copolymer without compromising the thermoplasticity of the network. Here, we use the facile water-based coupling of PEO-terminal azide and alkyne groups to demonstrate the scale of toughness enhancements possible through conversion of dangling ends into a second network. The dangling-end double networks produced exhibit remarkable improvements in tensile properties (tensile modulus, toughness, strain at break, and stress at break), including a 58-fold increase in mean toughness (to 361 kJ/m3) and a 19-fold increase in mean stress to break (to 169 kPa) in highly swollen samples containing up to 95% (g/g) water. Importantly, these improvements could be realized without altering water content, shape, small-strain dynamic shear, and unconfined compressive properties of the original TPE hydrogels.

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Section: Resultssupporting

confidence: 94%

Dangling-End Double Networks: Tapping Hidden Toughness in Highly Swollen Thermoplastic Elastomer Hydrogels

et al. 2016

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“…The reduction in tensile strength and Young’s modulus is likely due to the presence of l -ascorbic acid. Ascorbic acid accelerates the degradation of the polymer, particularly for the polymer with higher molecular weight . Given that PLLA/Cu (in Vc) was immersed in a Vc solution for an extended period, it suffered from a more significant loss of mechanical strength.…”

Section: Resultsmentioning

confidence: 99%

Hierarchically Porous, Superhydrophobic PLLA/Copper Composite Fibrous Membranes for Air Filtration

Huang,

Meng,

Liao

et al. 2024

ACS Appl. Polym. Mater.

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Epidemics such as pulmonary tuberculosis and pertussis can spread quickly through the air in enclosed or small spaces. Most of these diseases are caused by various bacteria. In hospitals, nursing homes, and biology laboratories, the requirement for air quality is often high. Particulate air filters can remove infectious bacteria from the air, making them a good choice for local ventilation systems to capture and remove bacteria or other pathogenic microbes. With high surface area, electrospun poly(l-lactic acid) (PLLA) fibrous membranes have the ability to capture small particles like bacteria. Moreover, copper has significant antimicrobial properties. In this Letter, we present a hierarchically porous PLLA membrane created through electrospinning and acetone treatment. Additionally, we describe two methods for loading copper particles onto the hierarchically porous PLLA membrane, thereby providing capabilities for capturing and killing bacteria. The experiments demonstrated that the final PLLA/Cu composite fibrous membranes exhibit not only excellent air permeability but also remarkable antimicrobial performance while maintaining bendability and superhydrophobic ability. This study provides a simple process, low energy cost, and environmentally friendly method to produce the copper-coated PLLA membrane, which is especially suitable for potential applications in high-flux filtration equipment in hospitals, nursing homes, and biology laboratories.

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“…PAM and PEO individually blend with other polymers, but to best of authors' knowledge, there isn't any interaction study of PAM and PEO polymer blends together. Only Vijayalakshmi et al has studied thermal degradation characterization of blend of PEO and PAM [30] [31]. In this article, we reported on the formulation and fabrication of free standing PAM/PEO blend films.…”

Section: Introductionmentioning

confidence: 91%

Spectroscopic Investigation and Characterizations of PAM/PEO Blends Films

Patel¹,

Sureshkumar²,

Patel³

2015

Soft

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Polymer blends have been obtained in the form of dimensionally stable and free standing films and their properties were characterized by different techniques. FTIR analysis and Raman spectroscopic analysis cleared the hydrogen bonding intermolecular interaction between-CONH2 groups in Poly Acrylamide (PAM) and CO -C and-CH2OH group in Poly Ethylene Oxide (PEO). From Differential Scanning Calorimeter (DSC) the study shows that crystallinity is increasing with PEO wt%. From polymer interaction parameter we also show that the polymer blend is miscible. Thermal stability of films is investigated by Thermo Gravimetric Analysis (TGA) and derivative Thermo Gravimetric Analysis (DrTG). From UV-Vis absorption spectra, absorption band edge, direct/ indirect band gap and optical activation energy have been calculated.

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Thermal degradation of poly(ethylene oxide) and polyacrylamide with ascorbic acid

Cited by 12 publications

References 17 publications

Dangling-End Double Networks: Tapping Hidden Toughness in Highly Swollen Thermoplastic Elastomer Hydrogels

Dangling-End Double Networks: Tapping Hidden Toughness in Highly Swollen Thermoplastic Elastomer Hydrogels

Hierarchically Porous, Superhydrophobic PLLA/Copper Composite Fibrous Membranes for Air Filtration

Spectroscopic Investigation and Characterizations of PAM/PEO Blends Films

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