Polymers

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8 pages, 3753 KiB

Open AccessArticle

Repeatable Crack Self-Healing by Photochemical [2 + 2] Cycloaddition of TCE-co-DCE Monomers Enclosed in Homopolymer Microcapsules

by Sunyoung Kim, Bo-Hyun Kim, Myongkeon Oh, Dong Hyuk Park and Sunjong Lee

Polymers 2019, 11(1), 104; https://doi.org/10.3390/polym11010104 - 09 Jan 2019

Cited by 10 | Viewed by 3361

Abstract

Self-healing, an autonomous repairing process stimulated by damage, has recently attracted a great deal of attention in the field of medical and mechanical engineering as well as from scientists, due to its valuable potential applications. However, as the self-healing process is mediated by [...] Read more.

Self-healing, an autonomous repairing process stimulated by damage, has recently attracted a great deal of attention in the field of medical and mechanical engineering as well as from scientists, due to its valuable potential applications. However, as the self-healing process is mediated by specific functional materials, practical applications have been limited. Here, we introduce a healable homopolymer microcapsule that can self-heal a crack or cleaved part through a photochemical [2 + 2] cycloaddition process. Microcapsules were prepared through photopolymerization and suspension polymerization, each containing 1,1,1-tris (cinnamoyloxymethyl) ethane (TCE) and 1,1-di (cinnamoyloxymethyl) ethane (DCE) monomers, which act as healing materials. TCE and DCE monomers were polymerized into poly (TCE-co-DCE) without a photoinitiator under illumination. The epoxy specimen embedded with microcapsules showed obvious healing performance during illumination after cracking. From the FT-IR spectra for each step of the healing process, the specimen could be repeatedly self-healed through the reversible process of cyclobutane cross-links to the original cinnamate and vice versa. This work shows an alternative approach using homopolymer microcapsules to accomplish the repeatable self-healing of a crack without interface discontinuity, which could be adopted as a healing substance in various paints. Full article

(This article belongs to the Special Issue Smart Polymers)

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16 pages, 2166 KiB

Open AccessArticle

Study of Physical and Degradation Properties of 3D-Printed Biodegradable, Photocurable Copolymers, PGSA-co-PEGDA and PGSA-co-PCLDA

by June-Yo Chen, Joanne V. Hwang, Wai-Sam Ao-Ieong, Yung-Che Lin, Yi-Kong Hsieh, Yih-Lin Cheng and Jane Wang

Polymers 2018, 10(11), 1263; https://doi.org/10.3390/polym10111263 - 13 Nov 2018

Cited by 45 | Viewed by 7489

Abstract

As acrylated polymers become more widely used in additive manufacturing, their potential applications toward biomedicine also raise the demand for biodegradable, photocurable polymeric materials. Polycaprolactone diacrylate (PCLDA) and poly(ethylene glycol) diacrylate (PEGDA) are two popular choices of materials for stereolithography (SLA) and digital [...] Read more.

As acrylated polymers become more widely used in additive manufacturing, their potential applications toward biomedicine also raise the demand for biodegradable, photocurable polymeric materials. Polycaprolactone diacrylate (PCLDA) and poly(ethylene glycol) diacrylate (PEGDA) are two popular choices of materials for stereolithography (SLA) and digital light processing additive manufacturing (DLP-AM), and have been applied to many biomedical related research. However, both materials are known to degrade at a relatively low rate in vivo, limiting their applications in biomedical engineering. In this work, biodegradable, photocurable copolymers are introduced by copolymerizing PCLDA and/or PEGDA with poly(glycerol sebacate) acrylate (PGSA) to form a network polymer. Two main factors are discussed: the effect of degree of acrylation in PGSA and the weight ratio between the prepolymers toward the mechanical and degradation properties. It is found that by blending prepolymers with various degree of acrylation and at various weight ratios, the viscosity of the prepolymers remains stable, and are even more 3D printable than pure substances. The formation of various copolymers yielded a database with selectable Young’s moduli between 0.67–10.54 MPa, and the overall degradation rate was significantly higher than pure substance. In addition, it is shown that copolymers fabricated by DLP-AM fabrication presents higher mechanical strength than those fabricated via direct UV exposure. With the tunable mechanical and degradation properties, the photocurable, biodegradable copolymers are expected to enable a wider application of additive manufacturing toward tissue engineering. Full article

(This article belongs to the Special Issue Smart Polymers)

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21 pages, 4471 KiB

Open AccessArticle

Facile, Scalable, Eco-Friendly Fabrication of High-Performance Flexible All-Solid-State Supercapacitors

by Jincy Parayangattil Jyothibasu and Rong-Ho Lee

Polymers 2018, 10(11), 1247; https://doi.org/10.3390/polym10111247 - 11 Nov 2018

Cited by 33 | Viewed by 6008

Abstract

A highly porous freestanding supercapacitor electrode has been fabricated through a simple, inexpensive, bulk-scalable, and environmentally friendly method, without using any extra current collector, binder, or conducting additive. Benefiting from its unique micro-tubular hollow structure with a thin cell wall and large lumen, [...] Read more.

A highly porous freestanding supercapacitor electrode has been fabricated through a simple, inexpensive, bulk-scalable, and environmentally friendly method, without using any extra current collector, binder, or conducting additive. Benefiting from its unique micro-tubular hollow structure with a thin cell wall and large lumen, kapok fiber (KF) was used herein as a low-cost template for the successive growth of polypyrrole (PPy) through in situ chemical polymerization. This PPy-coated KF (KF@PPy) was blended with functionalized carbon nanotubes (f-CNTs) to form freestanding conductive films (KF@PPy/f-CNT) through a simple dispersion and filtration method. The hybrid film featuring the optimal composition exhibited an outstanding areal capacitance of 1289 mF cm⁻² at a scan rate of 5 mV s⁻¹. Moreover, an assembled all-solid-state symmetric supercapacitor featuring a PVA/H₂SO₄ gel electrolyte exhibited not only areal capacitances as high as 258 mF cm⁻² (at a scan rate of 5 mV s⁻¹) but also excellent cycling stability (97.4% of the initial capacitance after 2500 cycles). Therefore, this efficient, low-cost, scalable green synthesis strategy appears to be a facile and sustainable way of fabricating high-performance flexible supercapacitors incorporating a renewable cellulose material. Full article

(This article belongs to the Special Issue Smart Polymers)

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12 pages, 2538 KiB

Open AccessArticle

Fabrication of Photothermo-Responsive Drug-Loaded Nanogel for Synergetic Cancer Therapy

by Ray Chang and Wei-Bor Tsai

Polymers 2018, 10(10), 1098; https://doi.org/10.3390/polym10101098 - 04 Oct 2018

Cited by 23 | Viewed by 4738

Abstract

Temperature stimulus, easy modulation in comparison to other environmental stimuli, makes thermo-responsive nanocarriers popular in the applications of controlled drug release for cancer therapy. In this study, photosensitive sodium copper chlorophyllin (SCC) was incorporated into thermo-responsive polymeric nanogels consisted of N-isopropylacrylamide and [...] Read more.

Temperature stimulus, easy modulation in comparison to other environmental stimuli, makes thermo-responsive nanocarriers popular in the applications of controlled drug release for cancer therapy. In this study, photosensitive sodium copper chlorophyllin (SCC) was incorporated into thermo-responsive polymeric nanogels consisted of N-isopropylacrylamide and N-(hydroxymethyl)acrylamide. Significant heat was generated from the SCC-containing nanogels under the exposure to 532-nm green laser, and resulted in cell mortality. The thermo-responsive nanogel loaded with 5-FU, an anti-cancer drug, released the drug explosively when exposed to green laser. The combination of hyperthermia and temperature-induced drug release via green laser irradiation greatly enhanced cell mortality to a maximal extent. Such photothermo-responsive nanogel possesses a great potential in anti-cancer treatment. Full article

(This article belongs to the Special Issue Smart Polymers)

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12 pages, 12283 KiB

Open AccessArticle

Light-Induced Actuation of Poly(dimethylsiloxane) Filled with Graphene Oxide Grafted with Poly(2-(trimethylsilyloxy)ethyl Methacrylate)

by Josef Osicka, Miroslav Mrlik, Markéta Ilčíková, Lukas Munster, Pavel Bazant, Zdenko Špitalský and Jaroslav Mosnáček

Polymers 2018, 10(10), 1059; https://doi.org/10.3390/polym10101059 - 24 Sep 2018

Cited by 6 | Viewed by 3578

Abstract

This study serves to combine two approaches into one single step, to achieve a significant improvement of the light-induced actuation capabilities. Graphene oxide (GO) is an inert material, from the electrical and thermal conductivity point of view, and is incompatible with the usually-used [...] Read more.

This study serves to combine two approaches into one single step, to achieve a significant improvement of the light-induced actuation capabilities. Graphene oxide (GO) is an inert material, from the electrical and thermal conductivity point of view, and is incompatible with the usually-used poly(dimethylsiloxane) (PDMS) matrix. During surface-modification by surface-initiated atom transfer radical polymerization, the GO was transformed into a conducting and compatible material with the PDMS showing enormous light-induced actuation capability. The GO surface-modification with poly(2-(trimethylsilyloxy)ethyl methacrylate) (PHEMATMS) chains was confirmed by transmission electron microscopy and thermogravimetric analysis, with an on-line monitoring of gasses using FTIR. The improved compatibility was elucidated using contact angle and dielectric properties measurements. The PHEMATMS shell was investigated using gel permeation chromatography and nuclear magnetic resonance. The improved electric conductivity was measured using the four-point probe method and by Raman spectroscopy. The very important mechanical properties were elucidated using dynamic mechanical analysis, and with the help of thermo-mechanic analysis for the light-induced actuation. The excellent actuation capabilities observed, with changes in the length of around 0.8% at 10% pre-strain, are very promising from the point of view of applications. Full article

(This article belongs to the Special Issue Smart Polymers)

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16 pages, 9223 KiB

Open AccessArticle

Synthesis of Poly(ε-caprolactone)-Based Miktoarm Star Copolymers through ROP, SA ATRC, and ATRP

by Venkatesan Sathesh, Jem-Kun Chen, Chi-Jung Chang, Junko Aimi, Zong-Cheng Chen, Yu-Chih Hsu, Yi-Shen Huang and Chih-Feng Huang

Polymers 2018, 10(8), 858; https://doi.org/10.3390/polym10080858 - 02 Aug 2018

Cited by 11 | Viewed by 5706

Abstract

The synthesis of novel branched/star copolymers which possess unique physical properties is highly desirable. Herein, a novel strategy was demonstrated to synthesize poly(ε-caprolactone) (PCL) based miktoarm star (μ-star) copolymers by combining ring-opening polymerization (ROP), styrenics-assisted atom transfer radical coupling (SA ATRC), and atom [...] Read more.

The synthesis of novel branched/star copolymers which possess unique physical properties is highly desirable. Herein, a novel strategy was demonstrated to synthesize poly(ε-caprolactone) (PCL) based miktoarm star (μ-star) copolymers by combining ring-opening polymerization (ROP), styrenics-assisted atom transfer radical coupling (SA ATRC), and atom transfer radical polymerization (ATRP). From the analyses of gel permeation chromatography (GPC), proton nuclear magnetic resonance (¹H NMR), and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), well-defined PCL-μ-PSt (PSt: polystyrene), and PCL-μ-PtBA (PtBA: poly(tert-butyl acrylate) μ-star copolymers were successfully obtained. By using atomic force microscopy (AFM), interestingly, our preliminary examinations of the μ-star copolymers showed a spherical structure with diameters of ca. 250 and 45 nm, respectively. We successfully employed combinations of synthetic techniques including ROP, SA ATRC, and ATRP with high effectiveness to synthesize PCL-based μ-star copolymers. Full article

(This article belongs to the Special Issue Smart Polymers)

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9 pages, 4241 KiB

Open AccessCommunication

Synthetic Glycopolypeptide Micelle for Targeted Drug Delivery to Hepatic Carcinoma

by Pengqiang Li, Jiandong Han, Di Li, Jinjin Chen, Wei Wang and Weiguo Xu

Polymers 2018, 10(6), 611; https://doi.org/10.3390/polym10060611 - 04 Jun 2018

Cited by 11 | Viewed by 3429

Abstract

The targeted delivery of chemotherapy drugs to tumor lesions is a major challenge for the treatment of tumors. Up until now, various polymeric nanoparticles have been explored to improve the targetability of these therapeutic drugs through passive or active targeting processes. In the [...] Read more.

The targeted delivery of chemotherapy drugs to tumor lesions is a major challenge for the treatment of tumors. Up until now, various polymeric nanoparticles have been explored to improve the targetability of these therapeutic drugs through passive or active targeting processes. In the design and construction of polymer nanoparticles, glycopolypeptide has shown great potential owing to its excellent targeting ability and biocompatibility. In order to enhance the antitumor effect of doxorubicin (DOX), a glycopolypeptide-based micelle (GPM) modified by α-lactose (Lac) was synthesized for targeted treatment of hepatoma. The DOX-loaded GPM (i.e., GPM/DOX) could significantly target human hepatoma (HepG2) cells and further inhibit their proliferation in vitro. Additionally, GPM/DOX exhibited a much higher drug accumulation in tumor tissue and a stronger antitumor effect in vivo than free DOX. The above results revealed that this drug delivery system provides a promising platform for the targeting therapy of hepatic cancer. Full article

(This article belongs to the Special Issue Smart Polymers)

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16 pages, 14192 KiB

Open AccessArticle

Reconfigurable Shape Memory and Self-Welding Properties of Epoxy Phenolic Novolac/Cashew Nut Shell Liquid Composites Reinforced with Carbon Nanotubes

by Pornnapa Kasemsiri, Narubeth Lorwanishpaisarn, Uraiwan Pongsa and Shinji Ando

Polymers 2018, 10(5), 482; https://doi.org/10.3390/polym10050482 - 28 Apr 2018

Cited by 28 | Viewed by 5701

Abstract

Conventional shape memory polymers (SMPs) can memorize their permanent shapes. However, these SMPs cannot reconfigure their original shape to obtain a desirable geometry owing to permanent chemically or physically crosslinked networks. To overcome this limitation, novel SMPs that can be reconfigured via bond [...] Read more.

Conventional shape memory polymers (SMPs) can memorize their permanent shapes. However, these SMPs cannot reconfigure their original shape to obtain a desirable geometry owing to permanent chemically or physically crosslinked networks. To overcome this limitation, novel SMPs that can be reconfigured via bond exchange reactions (BERs) have been developed. In this study, polymer composites consisting of epoxy phenolic novolac (EPN) and bio-based cashew nut shell liquid (CNSL) reinforced by multi-walled carbon nanotubes (CNTs) were prepared. The obtained composites exhibited shape memory and self-welding properties, and their shapes could be reconfigured via BERs. Their shape memory mechanisms were investigated using variable-temperature Fourier transform infrared spectroscopy and dynamic mechanical analysis. The EPN/CNSL composite containing 0.3 wt % CNTs showed the highest shape fixity and shape recovery ratio. Furthermore, shape memory behavior induced by irradiation of near-infrared (NIR) light was also observed. All samples showed high shape recovery ratios of nearly 100% over five cycles, and increasing the CNT content shortened the recovery time remarkably. The ability of shape reconfiguration and stress relaxation affected the photo-induced shape memory properties of reshaped samples. Additionally, the self-welding properties were also influenced by stress relaxation. The hindrance of stress relaxation caused by the CNTs resulted in a decrease in adhesive fracture energy (G_c). However, the G_c values of EPN/CNSL composites were comparable to those of epoxy vitrimers. These results revealed that the material design concepts of thermal- and photo-induced shape memory, shape reconfiguration, and self-welding were combined in the EPN/CNSL composites, which could be feasible method for advanced smart material applications. Full article

(This article belongs to the Special Issue Smart Polymers)

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16 pages, 14298 KiB

Open AccessArticle

Multi-Responsive Behaviors of Copolymers Bearing N-Isopropylacrylamide with or without Phenylboronic Acid in Aqueous Solution

by Jiaxing Li, Lei Yang, Xiaoguang Fan, Fei Wang, Jing Zhang and Zhanyong Wang

Polymers 2018, 10(3), 293; https://doi.org/10.3390/polym10030293 - 09 Mar 2018

Cited by 9 | Viewed by 3404

Abstract

Continuing efforts to develop novel smart materials are anticipated to upgrade the quality of life of humans. Thermo-responsive poly(N-isopropylacrylamide) and glucose-responsive phenylboronic acid—typical representatives—are often integrated as multi-stimuli-sensitive materials, but few are available for side-by-side comparisons with their properties. In this [...] Read more.

Continuing efforts to develop novel smart materials are anticipated to upgrade the quality of life of humans. Thermo-responsive poly(N-isopropylacrylamide) and glucose-responsive phenylboronic acid—typical representatives—are often integrated as multi-stimuli-sensitive materials, but few are available for side-by-side comparisons with their properties. In this study, both copolymers bearing N-isopropylacrylamide (NIPAAm), with or without 3-acrylamidophenylboronic acid (AAPBA), were synthesized by free radical polymerization, and characterized by Fourier transform infrared spectrometry, nuclear magnetic resonance hydrogen spectroscopy and gel permeation chromatography. Dynamic light scattering was used to analyze and compare the responsive behaviors of the copolymers in different aqueous solutions. Atomic force microscopy was also employed to investigate the apparent morphology changes with particle sizes. The results demonstrated that the introduction of NIPAAm endowed the composite materials with thermosensitivity, whereas the addition of AAPBA lowered the molecular weight of the copolymers, intensified the intermolecular aggregation of the nanoparticles, reduced the lower critical solution temperature (LCST) of the composites, and accordingly allowed the copolymers to respond to glucose. It was also concluded that the responding of smart copolymers to operating parameters can be activated only under special conditions, and copolymer dimension and conformation were affected by inter/intramolecular interactions. Full article

(This article belongs to the Special Issue Smart Polymers)

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7133 KiB

Open AccessArticle

Electrosynthesis of Copolymers Based on 1,3,5-Tris(N-Carbazolyl)Benzene and 2,2′-Bithiophene and Their Applications in Electrochromic Devices

by Chung-Wen Kuo and Po-Ying Lee

Polymers 2017, 9(10), 518; https://doi.org/10.3390/polym9100518 - 17 Oct 2017

Cited by 20 | Viewed by 5000

Abstract

Poly(1,3,5-tris(N-carbazolyl)benzene) (PtnCz) and three copolymers based on 1,3,5-tris(N-carbazolyl)benzene (tnCz) and 2,2′-bithiophene (bTp) were electrochemically synthesized. The anodic P(tnCz1-bTp2) film with a tnCz/bTp feed molar ratio of 1/2 showed four colors (light orange at 0.0 V, yellowish-orange at 0.7 V, [...] Read more.

Poly(1,3,5-tris(N-carbazolyl)benzene) (PtnCz) and three copolymers based on 1,3,5-tris(N-carbazolyl)benzene (tnCz) and 2,2′-bithiophene (bTp) were electrochemically synthesized. The anodic P(tnCz1-bTp2) film with a tnCz/bTp feed molar ratio of 1/2 showed four colors (light orange at 0.0 V, yellowish-orange at 0.7 V, yellowish-green at 0.8 V, and blue at 1.1 V) from the neutral state to oxidized states. The optical contrast (∆T%) and coloration efficiency (η) of the P(tnCz1-bTp2) film were measured as 48% and 112 cm²∙C⁻¹, respectively, at 696 nm. Electrochromic devices (ECDs) based on PtnCz, P(tnCz1-bTp1), P(tnCz1-bTp2), P(tnCz1-bTp4), and PbTp films as anodic polymer layers and poly(3,4-dihydro-3,3-dimethyl-2H-thieno[3,4-b-1,4]dioxepin) (PProDOT-Me₂) as cathodic polymer layers were assembled. P(tnCz1-bTp2)/PProDOT-Me₂ ECD showed three various colors (saffron yellow, yellowish-blue, and dark blue) at potentials ranging from −0.3 to 1.5 V. In addition, P(tnCz1-bTp2)/PProDOT-Me₂ ECD showed a high ∆T% value (40% at 630 nm) and a high coloration efficiency (519 cm²∙C⁻¹ at 630 nm). Full article

(This article belongs to the Special Issue Smart Polymers)

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3812 KiB

Open AccessArticle

Supramolecular Interactions Induce Unexpectedly Strong Emissions from Triphenylamine-Functionalized Polytyrosine Blended with Poly(4-vinylpyridine)

by Yu-Ru Jheng, Mohamed Gamal Mohamed and Shiao-Wei Kuo

Polymers 2017, 9(10), 503; https://doi.org/10.3390/polym9100503 - 12 Oct 2017

Cited by 13 | Viewed by 5968

Abstract

In this study, we synthesized a triphenylamine-functionalized polytyrosine (PTyr-TPA) through living ring opening polymerization with 4,4′-diamino-4″-methoxytriphenylamine (TPA-NH₂) as an initiator, and used Fourier transform infrared (FTIR) and nuclear magnetic resonance spectroscopy to confirm the chemical structure. Photoluminescence spectroscopy revealed the photophysical [...] Read more.

In this study, we synthesized a triphenylamine-functionalized polytyrosine (PTyr-TPA) through living ring opening polymerization with 4,4′-diamino-4″-methoxytriphenylamine (TPA-NH₂) as an initiator, and used Fourier transform infrared (FTIR) and nuclear magnetic resonance spectroscopy to confirm the chemical structure. Photoluminescence spectroscopy revealed the photophysical properties of TPA-NH₂ and PTyr-TPA and suggested that TPA-NH₂ exhibited aggregation-caused quenching; in contrast, attaching the initiator to the rigid rod conformation of the PTyr segments caused PTyr-TPA to display aggregation-induced emission behavior. Differential scanning calorimetry revealed single glass transition temperatures for miscible PTyr-TPA/P4VP blends, the result of intermolecular hydrogen bonding between the pyridine units of P4VP and the phenolic OH units of PTyr-TPA, as confirmed through FTIR spectroscopic analyses. Furthermore, the chain behavior of PTyr-TPA transformed from a β-sheet conformation to random coils after blending with P4VP, as determined using wide-angle X-ray diffraction. These findings suggest that the decreased emission intensity of PTyr-TPA resulted from release of the restricted intramolecular rotation of the triphenylamine moiety in the polypeptide center. Full article

(This article belongs to the Special Issue Smart Polymers)

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Review

Jump to: Research

25 pages, 1048 KiB

Open AccessReview

Thermoresponsive Hydrogels and Their Biomedical Applications: Special Insight into Their Applications in Textile Based Transdermal Therapy

by Sudipta Chatterjee, Patrick Chi-leung Hui and Chi-wai Kan

Polymers 2018, 10(5), 480; https://doi.org/10.3390/polym10050480 - 27 Apr 2018

Cited by 119 | Viewed by 12764

Abstract

Various natural and synthetic polymers are capable of showing thermoresponsive properties and their hydrogels are finding a wide range of biomedical applications including drug delivery, tissue engineering and wound healing. Thermoresponsive hydrogels use temperature as external stimulus to show sol-gel transition and most [...] Read more.

Various natural and synthetic polymers are capable of showing thermoresponsive properties and their hydrogels are finding a wide range of biomedical applications including drug delivery, tissue engineering and wound healing. Thermoresponsive hydrogels use temperature as external stimulus to show sol-gel transition and most of the thermoresponsive polymers can form hydrogels around body temperature. The availability of natural thermoresponsive polymers and multiple preparation methods of synthetic polymers, simple preparation method and high functionality of thermoresponsive hydrogels offer many advantages for developing drug delivery systems based on thermoresponsive hydrogels. In textile field applications of thermoresponsive hydrogels, textile based transdermal therapy is currently being applied using drug loaded thermoresponsive hydrogels. The current review focuses on the preparation, physico-chemical properties and various biomedical applications of thermoresponsive hydrogels based on natural and synthetic polymers and especially, their applications in developing functionalized textiles for transdermal therapies. Finally, future prospects of dual responsive (pH/temperature) hydrogels made by these polymers for textile based transdermal treatments are mentioned in this review. Full article

(This article belongs to the Special Issue Smart Polymers)

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