Relatively homogeneous network structures of temperature-responsive gels synthesized via atom transfer radical polymerization

Norioka, Chisa; Kawamura, Akifumi; Miyata, Takashi

doi:10.1039/d3sm00044c

Cited by 4 publications

(4 citation statements)

References 49 publications

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“…Typically, the complex network topology results in a static s and fluctuating f components of the scattered electric field of nonergodic network. Using nonergodic analysis and the partial heterodyne method, [ 2,81–90 ] the apparent diffusion coefficient, D A , is determined from the exponential decay of the time‐averaged intensity correlation, which is written as Equation

\begin{equation}{g}_2(\tau ) \equiv \frac{{{{\left\langle {I(t)I(t + \tau )} \right\rangle }}_T}}{{{{\left\langle {I(t)} \right\rangle }}_T^2}} = 1 + {\left[ {X{g}_1(\tau )} \right]}^2 + 2X(1 - X){g}_1(\tau )\end{equation}

where X is the ratio f /( f + s ) and g 1 (τ) is the fluctuating component of the field correlation function. This ratio, X , can be determined from the initial amplitude of the time–intensity correlation function, σ 2 ≡ g 2 (0) − 1 = X (2 − X ).…”

Section: Resultsmentioning

confidence: 99%

“…Typically, the complex network topology results in a static s and fluctuating f components of the scattered electric field of nonergodic network. Using nonergodic analysis and the partial heterodyne method, [2,[81][82][83][84][85][86][87][88][89][90] the apparent diffusion coefficient, D A , is determined from the exponential decay of the time-averaged intensity correlation, which is written as Equation 12g 2 (𝜏) ≡ ⟨I(t)I(t…”

Section: Resultsmentioning

confidence: 99%

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Properties of Cross‐Linked Poly‐l‐lysine Hydrogels across the Random Coil–Helix Transition

Wilcox,

Grinevich,

Linscott

et al. 2023

Macro Chemistry & Physics

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Hydrogels are key components of biological tissues and have applications in biomedicine and commercial industry. Many biological tissues are known to strain harden due to the semiflexible nature of the chains. Here, the mechancial properties of poly‐l‐lysine (PLL) hydrogels, whose network chains undergo a random coil–helix transition, are studied as a function of the polypeptide's structural changes. PLL is cross‐linked with poly(ethylene glycol)diglycidyl ether at cross‐link percents ranging from 3% to 6%. The conformation change and mechanical properties are investigated with circular dichroism and small and large amplitude oscillatory shear rheology, respectively. As a function of pH at low cross‐link percents, a transition from strain softening to strain hardening is observed as the network chains become helical that is similar to the behavior of biological filamentous gels and consistent with recent theoretical descriptions of network strain hardening. At higher cross‐link densities, the hydrogels become brittle due to stress concentration in inhomogeneous locations in the network, which is studied with dynamic light scattering. Overall, the random coil–helix transition has a significant effect on the nonlinear mechanical properties of PLL hydrogels. By understanding the hydrogel structure and response to environmental changes, their potential can be expanded as functional biomedical materials.

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\begin{equation}{g}_2(\tau ) \equiv \frac{{{{\left\langle {I(t)I(t + \tau )} \right\rangle }}_T}}{{{{\left\langle {I(t)} \right\rangle }}_T^2}} = 1 + {\left[ {X{g}_1(\tau )} \right]}^2 + 2X(1 - X){g}_1(\tau )\end{equation}

Section: Resultsmentioning

confidence: 99%

“…Typically, the complex network topology results in a static s and fluctuating f components of the scattered electric field of nonergodic network. Using nonergodic analysis and the partial heterodyne method, [2,[81][82][83][84][85][86][87][88][89][90] the apparent diffusion coefficient, D A , is determined from the exponential decay of the time-averaged intensity correlation, which is written as Equation 12g 2 (𝜏) ≡ ⟨I(t)I(t…”

Section: Resultsmentioning

confidence: 99%

Properties of Cross‐Linked Poly‐l‐lysine Hydrogels across the Random Coil–Helix Transition

Wilcox,

Grinevich,

Linscott

et al. 2023

Macro Chemistry & Physics

View full text Add to dashboard Cite

show abstract

“…Additionally, this may have an impact on the polymer's resistance, toughness, elasticity, viscosity, solubility, glass transition temperature (T g ), and melting point [56]. Because links prevent rotational movement between polymer chains, cross-linked polymers have a greater T g , and the molecular mobility nature is often assessed using the T g [46,[56][57][58]. Moreover, cross-linking makes the polymer chains heavier molecularly and less mobile, reducing the polymer's solubility.…”

Section: Hydrogel Preparationmentioning

confidence: 99%

An Overview of Polymeric Hydrogel Applications for Sustainable Agriculture

Vedovello,

Sanches,

da Silva Teodoro

et al. 2024

Agriculture

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Agriculture, a vital element of human survival, confronts challenges of meeting rising demand due to population growth and product availability in developing nations. Reliance on pesticides and fertilizers strains natural resources, leading to soil degradation and water scarcity. Addressing these issues necessitates enhancing water efficiency in agriculture. Polymeric hydrogels, with their unique water retention and nutrient-release capabilities, offer promising solutions. These superabsorbent materials form three-dimensional networks retaining substantial amounts of water. Their physicochemical properties suit various applications, including agriculture. Production involves methods like bulk, solution, and suspension polymerization, with cross-linking, essential for hydrogels, achieved through physical or chemical means, each with different advantages. Grafting techniques incorporate functional groups into matrices, while radiation synthesis offers purity and reduced toxicity. Hydrogels provide versatile solutions to tackle water scarcity and soil degradation in agriculture. Recent research explores hydrogel formulations for optimal agricultural performance, enhancing soil water retention and plant growth. This review aims to offer a comprehensive overview of hydrogel technologies as adaptable solutions addressing water scarcity and soil degradation challenges in agriculture, with ongoing research refining hydrogel formulations for optimal agricultural use.

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“…Nevertheless, Sakai and other research groups ,,− have conducted numerous studies to synthesize ordered cross-linked networks using precisely synthesized star-shaped polymers of uniform molecular weight as building blocks. They have achieved relatively highly ordered network structures.…”

Section: Introductionmentioning

confidence: 99%

Synthesizing Ordered Network Structures Using Linear Polymers: A Study on Optimal Synthetic Conditions

Ohshima,

Kwon,

Wang

et al. 2024

Macromolecules

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We have successfully synthesized linear bifunctional PNIPA polymers with uniform molecular weight using living radical polymerization. Our objective was to construct a polymer network with a consistent and an ordered structure. To achieve this, we prepared a solution with a concentration higher than the overlap concentration (C*) of the linear PNIPA polymers with uniform molecular weight. Next, we introduced a cross-linking agent to bond the polymer ends together. Under our experimental conditions using this linear PNIPA polymer, we prepared polymer networks at different concentrations: 1.2C*, 1.5C*, and 2.0C*. Notably, the polymer network formed at 1.2C*, which is slightly higher than the overlap concentration, exhibited a significantly more ordered structure compared to those prepared at 1.5C* or 2.0C*. This observation was substantiated by the analysis of the polymer network degradation products through SEC measurements and the SAXS results of the polymer network. In the case of PNIPA star-shaped polymers, it has been found that a uniform network structure can be obtained by preparing the polymer network at a concentration of about 2.0C*, which is much higher than C*. The difference in excluded volume between linear polymers and star polymers appears to play a pivotal role in favoring the formation of a more ordered network structure when the concentration reaches the overlap concentration threshold. In summary, our study showcases the successful synthesis of linear bifunctional PNIPA polymers with uniform molecular weight through living radical polymerization. Moreover, we demonstrate that by carefully controlling the concentration during polymer network synthesis, it is possible to achieve a relatively ordered structure, especially when the concentration slightly exceeds the overlap concentration threshold. The insights gained from our findings contribute to a better understanding of polymer network formation and have implications for the design and fabrication of advanced materials.

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Relatively homogeneous network structures of temperature-responsive gels synthesized via atom transfer radical polymerization

Abstract: The network structures of poly(N-isopropylacrylamide) (PNIPAAm) gels prepared by atom transfer radical polymerization (ATRP) were compared with those prepared by free radical polymerization (FRP), as a conventional radical polymerization. Temperature-responsive...

Cited by 4 publications

References 49 publications

Properties of Cross‐Linked Poly‐l‐lysine Hydrogels across the Random Coil–Helix Transition

Properties of Cross‐Linked Poly‐l‐lysine Hydrogels across the Random Coil–Helix Transition

An Overview of Polymeric Hydrogel Applications for Sustainable Agriculture

Synthesizing Ordered Network Structures Using Linear Polymers: A Study on Optimal Synthetic Conditions

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