Stimuli-responsive polymer nano-science: Shape anisotropy, responsiveness, applications

Lu, Chunliang; Urban, Marek W.

doi:10.1016/j.progpolymsci.2017.07.005

Cited by 114 publications

(28 citation statements)

References 212 publications

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“…Stimuli-responsive materials are important for diverse applications including actuators, sensors, tissue engineering, drug delivery, and soft robotics where they provide functionalities that are difficult to obtain by using passive materials. − Our interest here is in stimuli-responsive particle-filled polymer composites. , Such systems typically consist of a dense flexible chain polymer matrix (e.g., cross-linked elastomer) that exhibits a broad linear elastic regime and a mean physical mesh size that is small compared to the added rigid particles. Here, we consider a different polymer–particle composite scenario based on semiflexible biopolymer networks, which exhibit strong elastic nonlinearities, and particles that are soft and comparable in size to the network mesh.…”

Section: Introductionmentioning

confidence: 99%

Thermoresponsive Stiffening with Microgel Particles in a Semiflexible Fibrin Network

et al. 2019

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We report temperature-responsive soft composites of semiflexible biopolymer networks (fibrin) containing dispersed microgel colloidal particles of poly(N-isopropylacrylamide) (pNIPAM) that undergo a thermodynamically driven de-swelling transition above a Lower Critical Solution Temperature (LCST). Unlike standard polymer-particle composites, decreasing the inclusion volume of the particles (by increasing temperature)is concomitant with a striking increase of the overall elastic stiffness of the composite. We observe such a behavior over a wide composition space. The composite elastic shear modulus reversibly stiffens by up to 10-fold over a small change in temperature from 25-35°C. In isolation, the fibrin network and microgel suspension both soften with increased temperature, making the stiffening of the composites particularly significant. We hypothesize that stiffening is caused by contracting microgel particles adsorbing on the fibrin filaments and modifying the structure of the semiflexible network. We develop two phenomenological models that quantify this hypothesis in physically distinct manners, and the derived predictions are qualitatively consistent with our experimental data.

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Section: Introductionmentioning

confidence: 99%

Thermoresponsive Stiffening with Microgel Particles in a Semiflexible Fibrin Network

et al. 2019

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“…[ 12‐16 ] When stimuli‐responsive BCPs being dispersed in block selective solvents, by changing temperature, pH, addition of ionic salts or irradiation with suitable wavelength light, the morphology of BCP nano‐assemblies can be conveniently modulated. [ 26 ]…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Stimuli‐Responsive Block Copolymers and Block Copolymer Nano‐assemblies

2022

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Comprehensive Summary Block copolymers have aroused much interest, and their application has been rapidly expanded. In recent years, our group has committed to exploring synthesis and self‐assembly of block copolymers. We have designed and synthesized several new thermo‐responsive polymers and photo‐responsive polymers by living/controlled radical polymerization (LCRP) and investigated their stimuli‐responsive properties. Aiming at convenient and efficient synthesis of block copolymer nano‐assemblies, we have developed several methods based on polymerization‐induced self‐assembly (PISA). Herein, we give a short summary of our research in these years. The aim of this account is to stimulate innovative synthesis strategies of block copolymer nano‐assemblies, and promote more scientific research cooperation to face the exciting opportunities and challenges encountered in block copolymers. What is the most favorite and original chemistry developed in your research group? Thermo‐responsive polymers based on dialkylamine groups may be the such thing. It is found that the dialkylamine groups especially the diethylamine group act the predominant role to the thermo‐response, and based on this finding several new thermo‐responsive polymers and stimuli‐responsive block copolymer nano‐assemblies have been synthesized. How do you get into this specific field? Could you please share some experiences with our readers? Since 2004 I got Ph.D. degree in polymer chemistry and physics from Nankai University, I began my research mainly on polymer chemistry till now. I think it the most important to focus on a topic useful in science or in practical application, which helps to maintain interest continuously. How do you supervise your students? It is a good way to discuss with students timely and deeply. What is the most important personality for scientific research? Hard work and keen interest. What are your hobbies? What's your favorite book(s)? I like flower farming and fishing. When I retire, I think I will be a good farmer. Who influences you mostly in your life? My parents. They are simple, kind hearted and hardworking.

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“…Thermally responsive, smart materials have received significant attention in many research fields, including biomedicine, sensors, and separation technology because of their ability to undergo sharp changes in their physical properties as a result of small variations in temperature. − Most of these applications rely on the self-assembled organization of lower critical solution temperature (LCST)-based macromolecules that can yield ordered structures in a broad collection of morphologies, including micelles, vesicles, and multiscale hierarchical structures. , Such nanostructures are classically formed by self-assembly of amphiphilic block copolymers in water which associates the hydrophobic block because of the hydrophobic hydration, while the responsive block sterically stabilizes the aggregates and imparts them with temperature-regulating properties. , Recently, increasing attention has been given to the double-hydrophilic copolymers (DHCs) with thermally responsive blocks or segments. , Their conformational transition from hydrophilic coils to hydrophobic and contracted globules above the LCST has been widely used as a driving force for construction of LCST-switchable assemblies, some of which are considered promising as catalytic nanoreactors or drug delivery nanovectors. − While the past studies on DHCs mainly focused on the solution properties in relation to the temperature response, there are only a few examples on the DHCs self-assembly at T < LCST, , where all blocks are hydrophilic and soluble and the present hydrophobic interactions are considered insufficient to drive polymer micellization. In spite of this, such copolymers are able to form unique water-in-water mesophases in concentrated aqueous solutions, including body-centered-cubic, hexagonal, and lamellar lyotropic phases, provided that the blocks are incompatible and not completely hydrated. − For dilute DHCs systems, however, generation of loose internally disordered aggregates but not defined nanostructures has only been reported below LCST until now. , …”

Section: Introductionmentioning

confidence: 99%

“…1−3 Most of these applications rely on the self-assembled organization of lower critical solution temperature (LCST)-based macromolecules that can yield ordered structures in a broad collection of morphologies, including micelles, vesicles, and multiscale hierarchical structures. 4,5 Such nanostructures are classically formed by self-assembly of amphiphilic block copolymers in water which associates the hydrophobic block because of the hydrophobic hydration, while the responsive block sterically stabilizes the aggregates and imparts them with temperature-regulating properties. 3,6 Recently, increasing attention has been given to the double-hydrophilic copolymers (DHCs) with thermally responsive blocks or segments.…”

Section: ■ Introductionmentioning

confidence: 99%

Self-Assembly of a Thermally Responsive Double-Hydrophilic Copolymer in Ethanol–Water Mixtures: The Effect of Preferential Adsorption and Co-Nonsolvency

et al. 2018

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Lower alcohols can induce a combined collapse-swelling de-mixing transition (lower critical solution temperature (LCST)-type co-nonsolvency) in aqueous solutions of poly( N-isopropylacrylamide) (PNIPAM) by interacting with the polymer's amide groups. This interaction results in an increase of the total surface area of hydrophobic sites and destabilizes the chains. Here, we make use of this phenomenon to drive the counterintuitive self-assembly of a PNIPAM-containing double-hydrophilic graft copolymer in water-ethanol mixtures at T ≪ LCST. Rheological frequency sweeps are used to quantify the distinct solvation states of PNIPAM at various temperatures and ethanol concentrations. The energy stored through elastic deformation at the de-mixing transition is simply related to the solvent binding. We find that the storage modulus decreases progressively, but nonlinearly with ethanol concentration, which evidences a preferential solvation pattern. Analogously, through a combination of dynamic light scattering and transmission electron microscope analyses, we demonstrate that a low-temperature structure variation takes place by adding ethanol following a similar solvent-content morphology dependent model.

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Stimuli-responsive polymer nano-science: Shape anisotropy, responsiveness, applications

Cited by 114 publications

References 212 publications

Thermoresponsive Stiffening with Microgel Particles in a Semiflexible Fibrin Network

Thermoresponsive Stiffening with Microgel Particles in a Semiflexible Fibrin Network

Synthesis of Stimuli‐Responsive Block Copolymers and Block Copolymer Nano‐assemblies

Self-Assembly of a Thermally Responsive Double-Hydrophilic Copolymer in Ethanol–Water Mixtures: The Effect of Preferential Adsorption and Co-Nonsolvency

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