interpenetrating polymer networks
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Polymers ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 211
Author(s):  
Adrian Bele ◽  
Liyun Yu ◽  
Mihaela Dascalu ◽  
Daniel Timpu ◽  
Liviu Sacarescu ◽  
...  

Interpenetrating polymer networks (IPNs) represent an interesting approach for tuning the properties of silicone elastomers due to the possible synergism that may occur between the networks. A new approach is presented, which consists of mixing two silicone-based networks with different crosslinking pathways; the first network being cured by condensation route and the second network by UV curing. The networks were mixed in different ratios and the resulted samples yield good mechanical properties (improved elongations, up to 720%, and Young’s modulus, 1 MPa), thermal properties (one glass transition temperature, ~−123 °C), good dielectric strength (~50 V/μm), and toughness (63 kJ/m3).


2022 ◽  
Vol 23 (1) ◽  
pp. 339-348
Author(s):  
Santhosh priya Karjala ◽  
Vijay Kumar Kuttynadar Rajammal ◽  
Suresh Gopi ◽  
Rajesh Ravi ◽  
Devanathan Chockalingam ◽  
...  

The main objective of this study is to compare the interpenetrating polymer networks’ (IPNs) physical strengths with different variants of fibers. In this study, E-glass, carbon, and a combination of E-glass and carbon fiber (hybrid) have been taken as the reinforcement. Similarly, three combinations of the IPNs were chosen as the matrix material, namely epoxy / polyurethane (EP), vinyl ester / polyurethane (VP) and epoxy/vinyl ester (EV) as IPN blends. In order to thoroughly understand the physical characteristics of the combination of blends and fibers, nine variants (laminates) were fabricated: combinations of epoxy / polyurethane / E-glass (EPG), epoxy / polyurethane / carbon (EPC), epoxy / vinyl ester / glass / carbon (EPGC-hybrid), vinyl ester / polyurethane / glass (VPG), vinyl ester / polyurethane / carbon (VPC), vinyl ester / polyurethane / glass / carbon (VPGC), epoxy / vinyl ester / glass (EVG), epoxy / vinyl ester / carbon (EVC), and epoxy / vinyl ester / glass / carbon (EVGC-hybrid), all with help of a hand-layup technique. Furthermore, mechanical tests such as tensile, flexural, impact, and HDT (heat distortion temperature) were performed on all the variants as per the ASTM standards. Results shows that carbon fiber reinforcement with all IPN combinations has shown extraordinary performance (double fold) over the E-glass fiber reinforcement, whereas the hybrid (combination of E-glass/carbon) laminates have shown excellent characteristics over E-glass fiber reinforcement, irrespective of IPN matrix material. All the results were compared with each other and their corresponding variations were plotted as bar charts. ABSTRAK:  Objektif utama kajian ini adalah bagi membandingkan kekuatan fizikal rangkaian polimer saling menusuk (IPN) dengan pelbagai jenis gentian berbeza. Kajian ini mengguna pakai gentian kaca-E, karbon dan gabungan kaca-E dan gentian karbon (hibrid) sebagai penguat. Begitu juga, tiga kombinasi IPN dipilih sebagai bahan matrik, iaitu epoksi / poliuretan (EP), ester vinil / poliuretan (VP) dan epoksi / ester vinil (EV) sebagai campuran IPN. Bagi tujuan memahami secara mendalam ciri-ciri fizikal gabungan campuran dan gentian, sembilan varian (lamina) dihasilkan, malaui kombinasi seperti epoksi / poliuretan / kaca-E (EPG), epoksi / poliuretan / karbon (EPC), epoksi / ester vinil / kaca / karbon (EPGC-hibrid), ester vinil / poliuretan / kaca (VPG), ester vinil / poliuretan / karbon (VPC), ester vinil / poliuretan / kaca / karbon (VPGC), epoksi / ester vinil / kaca (EVG), epoksi / ester vinil / karbon (EVC), epoksi / ester vinil / kaca / karbon (EVGC-hibrid) dengan teknik susun atur lapisan menggunakan tangan. Selain itu, ujian mekanikal seperti tegangan, lenturan, hentaman dan HDT (suhu kelenturan panas) dilakukan pada semua varian mengikut piawaian ASTM. Dapatan kajian menunjukkan bahawa, penguat gentian karbon dengan semua kombinasi IPN telah menunjukkan prestasi luar biasa (dua kali ganda) daripada penguat gentian kaca-E, manakala lamina hibrid (campuran kaca-E / karbon) telah menunjukkan ciri-ciri sangat baik berbanding penguat gentian kaca-E tanpa mengira bahan matrik IPN. Semua hasil dapatan dibandingkan antara satu sama lain dan padanan variasi diplot sebagai carta bar.


Polymers ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 115
Author(s):  
Silvia Franco ◽  
Elena Buratti ◽  
Valentina Nigro ◽  
Monica Bertoldo ◽  
Barbara Ruzicka ◽  
...  

Stimuli-responsive microgels have recently attracted great attention in fundamental research as their soft particles can be deformed and compressed at high packing fractions resulting in singular phase behaviours. Moreover, they are also well suited for a wide variety of applications such as drug delivery, tissue engineering, organ-on-chip devices, microlenses fabrication and cultural heritage. Here, thermoresponsive and pH-sensitive cross-linked microgels, composed of interpenetrating polymer networks of poly(N-isopropylacrylamide) (PNIPAM) and poly(acrylic acid) (PAAc), are synthesized by a precipitation polymerization method in water and investigated through differential scanning calorimetry in a temperature range across the volume phase transition temperature of PNIPAM microgels. The phase behaviour is studied as a function of heating/cooling rate, concentration, pH and PAAc content. At low concentrations and PAAc contents, the network interpenetration does not affect the transition temperature typical of PNIPAM microgel in agreement with previous studies; on the contrary, we show that it induces a marked decrease at higher concentrations. DSC analysis also reveals an increase of the overall calorimetric enthalpy with increasing concentration and a decrease with increasing PAAc content. These findings are discussed and explained as related to emerging aggregation processes that can be finely controlled by properly changing concentration, PAAc content an pH. A deep analysis of the thermodynamic parameters allows to draw a temperature– concentration state diagram in the investigated concentration range.


2021 ◽  
Vol 43 (4) ◽  
pp. 287-294
Author(s):  
N.V. YAROVA ◽  
◽  
T.F. SAMOILENKO ◽  
L.M. YASHCHENKO ◽  
O.O. BROVKO ◽  
...  

The distinct features of UV induced polymerization of epoxy-acrylate blends leading to the formation of simultaneous interpenetrating polymer networks (IPNs) have been studied. Different ratios of components within a prevailing content of an epoxy one have been used for the synthesis. Such a content of epoxy monomer is required to create a barrier preventing oxygen diffusion into a curing sample. It allows retardation of the well-known oxygen-inhibition effect, which acrylate monomers are susceptible to. Hence, the conduction of their polymerization in open-air conditions is possible. The proceeding of the polymerization reactions of acrylate (TEGDM) via free radical mechanism and of epoxy (UP-650D) via cationic one have been monitored by FTIR-spectroscopy. Namely, the conversion degrees have been calculated for double bonds of TEGDM and for epoxy groups of UP-650D respectively. A mixture of triphenylsulfonium hexafluorophosphate salts, which is capable of generating both free radical and cationic reactive species, have been used as a single photoinitiator for the formulations being investigated. Almost complete conversion of acrylate double bonds was reached after 60 min of UV irradiation irrespective of epoxy content. On the contrary, conversion of epoxy groups of aliphatic epoxy, which is known to be rather unreactive towards cationic photopolymerization, when mixed may be either higher or lower compared to the neat epoxy network. Such results are attributed to dual influence of acrylate network on the formation of epoxy one. Firstly, cationic polymerization of epoxy component is sensitized by acrylate macroradicals in terms of free radical promoted cationic polymerization. On the other hand, the mobility of epoxy macrocations is restricted by the rapid build-up of acrylate network. At the weight ratio of UP-650D and TEGDM 70/30 the sensitizing effect of acrylate is revealed to be dominant, so the given composition may be considered as optimal. Regardless of low conversion of epoxy groups, the content of the estimated gel fraction is high, and the epoxy component is found not to be leached in the process of extraction in acetone. Furthermore, physicomechanical properties of obtained UV-cured IPNs have been investigated. The results of the measurements, namely, impact resistance by the Gardner test, crosshatch adhesion test to different substrates (including silicon), and accelerated weathering test in a climatic chamber, show that all the samples exhibit good operational properties essential for effective protecting coatings of outdoor exposure.


Molecules ◽  
2021 ◽  
Vol 26 (22) ◽  
pp. 6975
Author(s):  
Ecaterina Stela Dragan ◽  
Maria Valentina Dinu ◽  
Claudiu Augustin Ghiorghita ◽  
Maria Marinela Lazar ◽  
Florica Doroftei

Curcumin (CCM) is a natural hydrophobic polyphenol known for its numerous applications in the food industry as a colorant or jelly stabilizer, and in the pharmaceutical industry due to its anti-inflammatory, antibacterial, antioxidant, anti-cancer, and anti-Alzheimer properties. However, the large application of CCM is limited by its poor solubility in water and low stability. To enhance the bioavailability of CCM, and to protect it against the external degradation agents, a novel strategy, which consists in the preparation of semi-interpenetrating polymer networks, (s-IPNs) based on poly(N,N-dimethylaminoethyl methacrylate) entrapped in poly(acrylamide) networks, by a cryogelation technique, was developed in this work. All s-IPN cryogels were characterized by SEM, EDX, FTIR, and swelling at equilibrium as a function of pH. Functionalization of semi-IPN cryogel with monochlorotriazinyl-β-cyclodextrin (MCT-β-CD) led to IPN cryogel. The release profile of CCM from the composite cryogels was investigated at 37 °C, in pH 3. It was found that the cumulative release increased with the increase of the carrier hydrophobicity, as a result of increasing the cross-linking degree, the content and the molar mass of PDMAEMA. Fitting Higuchi, Korsmeyer–Peppas, and first order kinetic models on the CCM release profiles indicated the diffusion as the main driving force of drug release from the composite cryogels.


2021 ◽  
Author(s):  
Guangzhe Gao ◽  
Xiance Wang ◽  
Mingtao Chen ◽  
Christopher N. Bowman ◽  
Jeffrey W. Stansbury

Antioxidants ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1816
Author(s):  
Emiliano Bedini ◽  
Alfonso Iadonisi ◽  
Chiara Schiraldi ◽  
Laura Colombo ◽  
Diego Albani ◽  
...  

Chondroitin sulfates (CS) are a class of sulfated glycosaminoglycans involved in many biological processes. Several studies reported their protective effect against neurodegenerative conditions like Alzheimer’s disease. CS are commonly derived from animal sources, but ethical concerns, the risk of contamination with animal proteins, and the difficulty in controlling the sulfation pattern have prompted research towards non-animal sources. Here we exploited two microbiological-chemical sourced CS (i.e., CS-A,C and CS-A,C,K,L) and Carbopol 974P NF/agarose semi-interpenetrating polymer networks (i.e., P.NaOH.0 and P.Ethanol.0) to set up a release system, and tested the neuroprotective role of released CS against H2O2-induced oxidative stress. After assessing that our CS (1–100 µM) require a 3 h pre-treatment for neuroprotection with SH-SY5Y cells, we evaluated whether the autoclave type (i.e., N- or B-type) affects hydrogel viscoelastic properties. We selected B-type autoclaves and repeated the study after loading CS (1 or 0.1 mg CS/0.5 mL gel). After loading 1 mg CS/0.5 mL gel, we evaluated CS release up to 7 days by 1,9-dimethylmethylene blue (DMMB) assay and verified the neuroprotective role of CS-A,C (1 µM) in the supernatants. We observed that CS-A,C exhibits a broader neuroprotective effect than CS-A,C,K,L. Moreover, sulfation pattern affects not only neuroprotection, but also drug release.


2021 ◽  
pp. 107384
Author(s):  
Chunhui Qu ◽  
Nan Zhang ◽  
Chengkun Wang ◽  
Tingmei Wang ◽  
Qihua Wang ◽  
...  

2021 ◽  
Author(s):  
Priscila Siqueira ◽  
Ana de Lima ◽  
Felipe Medeiros ◽  
Augusta Isaac ◽  
Katia Novack ◽  
...  

Abstract The hydrogels are advanced materials used in biomedical applications during wound healing, controlled drug release and to prepare scaffolds. In this work are prepared hydrogels of alginate/chitosan (Alg/Ch) semi-interpenetrating polymer networks (semi-IPN’s) and nanocelluloses. The hydrogels after preparation by freeze drying are namely simply as gels. The cellulose nanocrystals (CNC’s) are obtained from acid hydrolysis of bleached Eucalyptus pulps and oxidized cellulose nanocrystals (CNCT’s) prepared by (2,2,6,6-tetramethylpiperidin-1-yl)oxyl radical catalyzed reaction as known as TEMPO reaction. The cellulose nanofibers (NFC’s) are obtained from mechanical shearing of cellulose pulps and oxidized NFC’s by TEMPO-mediated reaction (NFCT’s). The nanocellulose suspension and gels are characterized by FTIR at ATR mode, TGA, XRD, TEM, SEM, X-ray computed microtomography (micro-CT) and DMTA. The addition of CNC’s, NFC’s, CNCT’s or NFCT’s in the microstructure of gels increases their dimensional stabilities. The best results are obtained when CNCT’s and NFCT’s are added. The mechanical properties and dimensional stability of Alg/Ch semi-IPN’s increase after controlled thermal post-treatment. The heating during thermal post-treatment boosts the physicochemical interactions in the microstructures of semi-IPN’s. The biological assays show biocompatibility of fibroblast cells on the substrates, and differentiation and proliferation up seven days. The optimized mechanical properties, dimensional stability and biocompatibility of the gels studied in this work are important parameters for potential biomedical applications of these biomaterials.


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