Wide-band underwater acoustic absorption based on locally resonant unit and interpenetrating network structure

The interpenetrating network structure provides an interesting avenue to novel materials. Locally resonant phononic crystal （LRPC） exhibits excellent sound attenuation performance based on the periodical arrangement of sound wave scatters. Combining the LRPC concept and interpenetrating network glassy structure, this paper has developed a new material which can achieve a wide band underwater strong acoustic absorption. Underwater absorption coefficients of different samples were measured by the pulse tube. Measurement results show that the new material possesses excellent underwater acoustic effects in a wide frequency range.Moreover, in order to investigate impacts of locally resonant units,some defects are introduced into the sample. The experimental result and the theoretical calculation both show that locally resonant units being connected to a network structure play an important role in achieving a wide band strong acoustic absorption.

Compressive Creep Behavior of TiC/AZ91D Magnesium-matrix Composites with Interpenetrating Networks

The 42.1 vol. pct TiC/AZ91D magnesium-matrix composites with interpenetrating networks were fabricated by in-situ reactive infiltration process. The compressive creep behavior of as-synthesized composites was investigated at temperature ranging from 673 to 723 K under loads of 95-108 MPa. For a comparative purpose,the creep behavior of the monolithic matrix alloy AZ91D was also conducted under loads of 15-55 MPa at 548-598 K. The creep mechanisms were theoretically analyzed based on the power-law relation. The results showed that the creep rates of both TiC/AZ91D composites and AZ91D alloy increase with increasing the temperature and load. The TiC/AZ91D composites possess superior creep resistance as compared with the AZ91D alloy. At deformation temperature below 573 K, the stress exponent n of AZ91D alloy approaches theoretical value of 5, which suggests that the creep process is controlled by dislocation climb. At 598 K, the stress exponentof AZ91D is close to 3, in which viscous non-basal slip deformation plays a key role in the process of creep deformation. However, the case differs from that of AZ91D alloy when the stress exponent n of TiC/AZ91D composites exceeds 9, which shows that there exists threshold stress in the creep process of the composites, similar to other types of composites. The average activation energies for the creep of the AZ91D alloy and TiC/AZ91D composites were calculated to be 144 and 152 k J/mol, respectively. The existence of threshold stress in the creep process of the composites leads to an increase in activation energy for creep.

Preparation and Swelling Behavior of L-Lactide Interpenetrating Networks

Novel triblock copolymers of poly (L-lactide)-poly (ethylene glycol)-sebacate-poly (ethylene glycol)-poly (L-lactide) were synthesized by Ring-Opening Polymerization of different ratios of L-lactide with other three pre-prepared poly (ethylene glycol)-sebacate-poly (ethylene glycol) polymers, coded A, B and C which had different poly (ethyleneglycol) chain lengths. The copolymers were characterized by FTIR and 1H NMR spectroscopy, which indicated that the reaction of ROP took place and led to producing nine triblock copolymers having new different lactide chain lengths (n = 10, 25 and 50), AL10, AL25, AL50,BL10, BL25, BL50, CL10, CL25, and CL50. Nine polymer networks were also prepared from copolymers with sodium alginate S1 - S9 and finally mixed with a solution of hydroxyl ethyl cellulose to form SH1 - SH9.

High Water Resistance and Enhanced Mechanical Properties of Bio-Based Waterborne Polyurethane Enabled by in-situ Construction of Interpenetrating Polymer Network

In this study,acrylic acid was used as a neutralizer to prepare bio-based WPU with an interpenetrating polymer network structure by thermally induced free radical emulsion polymerization.The effects of the content of acrylic acid on the properties of the resulting waterborne polyurethane-poly(acrylic acid)(WPU-PAA)dispersion and the films were systematically investigated.The results showed that the cross-linking density of the interpenetrating network polymers was increased and the interlocking structure of the soft and hard phase dislocations in the molecular segments of the double networks was tailored with increasing the content of acrylic acid,leading to enhancement of the mechanical properties and water resistance of WPU-PAA films.Notably,with the increase in content of acrylic acid,the tensile strength,Young’s modulus,and toughness of the WPU-PAA-110 film increased by 3 times,and 8 times,and 2.4 times compared with WPU-PAA-80,respectively.The WPU-PAA-100 film showed the best water resistance,and the water absorption rate at 96 h was only 3.27%.This work provided a new design scheme for constructing bio-based WPU materials with excellent properties.

Lighted up by hydrogen-bonding: luminescence behavior and applications of AIEgen-doped interpenetrating network hydrogel

The interaction between the aggregation-induced emissive(AIE) luminogens(AIEgen) and the polymer is the key scientific question in the design of functional AIE hydrogels. In this study, we report the AIE behavior of a poly(acrylic acid)(PAAc) and poly(acrylamide)(PAAm) interpenetrating network(IPN) hydrogel doped with tetra-cationic tetraphenylethene(TCTPE). The cationic AIEgen can bind with PAAc through ionic interaction, while PAAc and PAAm chains can associate with each other through hydrogen-bonds(H-bonds). These two interactions can restrict the intramolecular rotation and thus activate the luminescence of the AIEgen. The PAAc-PAAm H-bonds can be broken by increasing temperature or p H, restoring the intramolecular rotation of the AIEgen and quenching the fluorescence of the hydrogel. Therefore, the TCTPE-doped IPN hydrogel is designed as temperature-and p H-sensitive displayers which can record information imprinted by photo-printing or iono-printing with good switchability and reversibility. Another application of this TCTPE-doped hydrogel is demonstrated as a luminescent soft actuator, which has fast shape deformation and editable fluorescence pattern. The above results reveal a pathway to tune the emission behavior through tuning polymer-polymer and polymer-AIEgen interactions, which may inspire new design strategies of aggregation-induced emissive polymers and broaden their applications.

Reproducible and low-power multistate bio-memristor from interpenetrating network electrolyte design

Bio-memristor can address the inherent limitations of conventional memory components in artificial perceptual systems due to their biocompatibility with biological tissue.The actual deployment of bio-memristor is restricted by the lack of reproducibility,high power consumption,and insufficient storage capacity.Here,a reproducible and low-power multistate biomemristor is developed by designing the chitosan(CS)-reduced graphene oxide(rGO)interpenetrating network electrolyte.The interpenetrating network structure of the CS-rGO electrolyte reinforces structural stability and improves ionic conductivity.The bio-memristor equipped with CS-rGO active layer shows stable bipolar resistive switching up to 100 consecutive cycles,reproducible multistate storage with six different memory states,and low programming power of 9.4μW.The fabricated biocompatible CS-rGO device also exhibits deformation stability of memory operation over 103 bending cycles,high biocompatibility with HEK293 cells,and skin adhesion.This work provides an enlightening design strategy to develop highperformance bio-memristors for applications in artificial perceptual systems.

Tailored Carrier Transport Path by Interpenetrating Networks in Cathode Composite for High Performance All‑Solid‑State Li‑SeS_(2) Batteries

All-solid-state Li-SeS_(2) batteries(ASSLSs)are more attractive than traditional liquid Li-ion batteries due to superior thermal stability and higher energy density.However,various factors limit the practical application of all-solid-state Li-SeS_(2) batteries,such as the low ionic conductivity of the solid-state electrolyte and the poor kinetic property of the cathode composite,resulting in unsatisfactory rate capability.Here,we employed a traditional ball milling method to design a Li_(7)P_(2.9)W_(0.05)S_(10.85) glass–ceramic electrolyte with high conductivity of 2.0 mS cm^(−1) at room temperature.In order to improve the kinetic property,an interpenetrating network strategy is proposed for rational cathode composite design.Signifcantly,the disordered cathode composite with an interpenetrating network could promote electronic and ionic conduction and intimate contacts between the electrolyte–electrode particles.Moreover,the tortuosity factor of the carrier transport channel is considerably reduced in electrode architectures,leading to superior kinetic performance.Thus,assembled ASSLS exhibited higher capacity and better rate capability than its counterpart.This work demonstrates that an interpenetrating network is essential for improving carrier transport in cathode composite for high rate all-solid-state Li-SeS_(2) batteries.

PREPARATION AND PROPERTIES OF GEL POLYMER ELECTROLYTE BASED ON PVDF/ACRYLATE INTERPENETRATING POLYMER NETWORK FOR DYE-SENSITIZED SOLAR CELL

The gel polymer electrolytes（GPEs）based on poly（vinylidence fluoride）（PVDF）/acrylate interpenetrating polymer network（IPN）are prepared.The micro-phase separation type GPEs are characterized by Fourier transform infrared（FTIR）spectroscopy,scanning electron microscope（SEM）,respectively.Moreover,the conductivity and the voltage-current curves of the electrolytes are measured by electrochemical workstation.The higher porosity and electrolyte uptake are observed in the membranes prepared at lower crosslinker concentration.The suitable cross-linking acrylate monomer improves the porosity and the electrochemical behavior of GPE.A dye-sensitized solar cell（DSSC）employing PGE based on PVDF/poly（ethylene glycol dimethacrylate）（PEGDMA）IPN yields an open-circuit voltage of 0.674 V,short-circuit current of 8.476 mA·cm-2and the conversion efficiency of 2.710% under 100 mW·cm-2illumination.

SYNTHESIS,CHARACTERIZATION AND PROPERTIES OF ORGANOCLAYMODIFIED POLYSULFONE/EPOXY INTERPENETRATING POLYMER NETWORK NANOCOMPOSITES

Organoclay-modified hydroxylterminated polysulfone (PSF)/epoxy interpenetrating network nanocomposites (oM-PSF/EP nanocomposites) were prepared by adding organophilic montmorillonite (oMMT) to interpenetrating polymer networks (IPNs) of polysulfone and epoxy resin (PSF/EP) using diaminodiphenylmethane (DDM) as curing agent.The mechanical properties like tensile strength,tensile modulus,flexural strength,flexural modulus and impact properties of the nanocomposites were studied as per ASTM standards.Different...

Studies on the Morphology of Natural Rubber/Polyacrylate Interpenetrating Polymer Networks

The interpenetrating polymer network(IPN) systems have attracted a lot of attention because of their unique two-phase structure and properties. There have been many publications concerning the IPNs in which poly (isoprene) (PIP) or polyacrylates (PAC) is formed as one of the networks.In the present study, Four serles of natural rubber(NR)/PAC IPNs were prepared and their morphologies were investigated with dynamic mechanics analysis(DMA) and transmission electron microscopy (TEM).

Structural characteristics and properties of polyurethane modified TDE-85/MeTHPA epoxy resin with interpenetrating polymer networks

Diglycidyl-4,5-epoxycyclohexane-1,2-dicarboxylate(TDE-85)/methyl tetrahydrophthalic anhydride (MeTHPA) epoxy resin was modified with polyurethane(PU) and the interpenetrating polymer networks(IPNs) of PU-modified TDE-85/MeTHPA resin were prepared. The structural characteristics and properties of PU-modified TDE-85/MeTHPA resin were investigated by Fourier transform infrared(FTIR) spectrum,emission scanning electron microscopy(SEM) and thermogravimetry(TG). The results indicate that epoxy polymer network (Ⅰ) and polyurethane polymer network (Ⅱ) of the modified resin can be obtained and the networks (Ⅰ) and (Ⅱ) interpenetrate and tangle highly each other at the phase interface. The micro morphology presents heterogeneous structure. The integrative properties of PU-modified TDE-85/MeTHPA epoxy resin are improved obviously. The PU-modified TDE-85/ MeTHPA resin's tensile strength reaches 69.39 MPa,the impact strength reaches 23.56 kJ/m,the temperature for the system to lose 1% mass (t1%) is 300 ℃,and that for the system to lose 50% mass (t50%) is 378 ℃. Compared with those of TDE-85/MeTHPA resin,the tensile strength,impact strength,t1% and t50% of the PU-modified resin increases by 48%,115%,30 ℃,11 ℃,respectively. The PU-modified TDE-85/MeTHPA resin has the structure characteristics and properties of interpenetrating polymer networks.

Preparation,Morphology and Damping Property of PU/UP Interpenetrating Polymer Networks

Interpenetrating polymer networks （IPNs） composed of acrylate-modified polyurethane （PU）/unsaturated polyester （UP） resin via simultaneous polymerization with various component ratios of PU/UP were prepared. The polymerization processes of IPNs were traced through infrared spectrum （IR） techniques, by which the phase separation in systems could be controlled effectively. Results for the morphology and miscibility among multiple phases of IPNs, obtained by transmission electron microscope （TEM） indicated that the domains between two phases were constricted in nanometer scales. The dynamic mechanical thermal analyzer （DMTA） detection results revealed that the loss factor （tanS） and loss modulus （E″） increased with the polyurethane amounts in system, and the peak value in curves of tanδ and E″ appeared toward low temperature ranges. Maximum tanδ values of all samples were above 0.3 in the nearly 50℃ ranges. Also, the mechanical properties of PU/UP IPNs were studied in detail.

Polymerization Process and Morphology of Polyurethane/Vinyl Ester Resin Interpenetrating Polymer Networks

A series of polyurethane （PU）/vinyl ester resin （VER） simultaneous IPNs （interpenetrating polymer networks） with different component ratios and comonomers types introduced to VER were synthesized and the polymerization processes were traced by Fourier transform infrared spectroscopy （FTIR） to study the kinetics of IPNs and hydrogen bonding action within multi-component. Furthermore, the relationship of polymerization process with morphology was investigated in detail for the first time by the morphological information given by chemical action between two networks besides physical entanglement, atomic force microscope （AFM） observation and dynamic mechanical analysis （DMA）. The results indicated that the degree of hydrogen bonding （Xb,UT,%）, calculated from functional group conversional rate and fine structures gained from FT-IR spectra of two networks, were affected by PU/VER weight ratios and comonomer types of VER. The relationship of formation kinetics and morphology showed that the change of Xb,UT （%） values exhibited excellent consistency with that of phase sizes observed by AFM and detected by DMA.

Synthesis and Characterization of Polyurethane and Epoxy Resin Interpenetrating Polymer Network

A series of Polyurethane (PU)/bisphenol A based Epoxy Resin(EP) Interpenetrating Polymer Networks(IPN) were synthesized and characterized by SEM, DSC, TGA and DMTA. It was found that IPN shows the best compatibility and damping properties when the ratio of PU/EP is 80 to 20. The results show that chain-extender and higher molecular weight of PPG are able to improve the properties of compatibility, damping and thermal properties.

Thermoreversible Thickening and Self-assembly Behaviors of pH/Temperature Dually Responsive Microgels with Interpenetrating Polymer Network Structure

The pH /temperature dually responsive microgels of interpenetrating polymer network( IPN) structure composed of poly( N-isopropylacrylamide)( PNIPAM) network and poly( acrylic acid)( PAA) network( PNIPAM /PAA IPN microgels) were synthesized by seed emulsion polymerization. The results obtained by dynamic laser light scattering( DLLS) show that the microgels have good pH /temperature dual sensitivities. The temperature sensitive component and the pH sensitive component inside the microgels have little interference with each other. The rheological properties of the concentrated PNIPAM /PAA IPN microgel dispersions as a function of temperature at pH 4. 0 or 7. 0 were investigated by viscometer,and the results displayed that only at pH 7. 0 the dispersions presented thermoreversible thickening behavior. Then the PNIPAM /PAA fibers were prepared by self-assembly of the PNIPAM /PAA IPN microgels in the ice-crystal templates formed by unidirectional liquid nitrogen freezing method. Field emission scanning electron microscopy( FESEM) images indicate that the PNIPAM /PAA fibers are rounded,randomly orientated and interweaved.

SYNTHESIS AND CHARACTERIZATION OF POLYDIMETHYLSILOXANE/POLYSTYRENE SEMIINTERPENETRATING POLYMER NETWORKS

The synthesis of pseudo- and semi-interpenetrating polymer networks (IPNs) based on polydimethylsiloxane (PDMS) and polystyrene (PS) is described. IPNs were obtained by simultaneous and in situ sequential synthesis procedure. The preliminary studies on IPNs properties such as transition temperature, microphase separation and mechanical behaviors have been carried out by using differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The experimental evidence clearly showed that semi-IPNs obtained by sequential synthesis procedure have higher interpenetrating extent than pseudo-IPNs synthesized by simultaneous procedure. Over the full composition, the PDMS/PS IPNs are immiscible. The pseudo-IPNs microphase separation can be greatly subdued through the formation of grafting bonds between two networks as well as the kinetic rate-matching of the individual network crosslinking.

IMPROVED OXYGEN PERMEABILITY AND MECHANICAL STRENGTH OF SILICONE HYDROGELS WITH INTERPENETRATING NETWORK STRUCTURE

The interpenetrating polymer network(IPN) silicone hydrogels with improved oxygen permeability and mechanical strength were prepared by UV-initiated polymerization of monomers including methacryloxypropyl tris(trimethylsiloxy)silane(TRIS),2-hydroxyethylmethacrylate(HEMA) and N-vinyl pyrrolidone(NVP) in the presence of free radical photoinitiator and cationic photoinitiator.The polymerization mechanism was investigated by the formation of gel network.The structure of IPN hydrogels was characterized by Fourier transform infrared spectroscopy(FTIR), differential scanning calorimetry(DSC) and transmission electron microscopy(TEM).The results showed that the IPN hydrogels exhibited a heterogeneous morphology.The mechanical properties,surface wettability and oxygen permeability were examined by using a tensile tester,a contact angle goniometer and an oxygen transmission tester,respectively.The equilibrium water content of the hydrogels was measured by the gravimetric method.The results revealed that the IPN hydrogels possessed hydrophilic surface and high water content.They exhibited improved oxygen permeability and mechanical strength because of the incorporation of TRIS.

Microstrueture and Properties of Fluoroelastomer/Butadiene-Acrylonitrile Rubber Interpenetrating Polymer Networks

Interpenetrating polymer networks （IPNs） based on fluoroelastomer/butadiene-acrylonitrile rubber （FKM/NBR） by molten blending at a high temperature and chemical cross-linking of two components were prepared. The influence of the two networks component on the mechanical properties and thermostabilities was studied. The experimental results show that the mechanical properties of the IPNs are superior to those of the individual FKM and NBR networks due to forming the case of interpenetrating and intercross-linking between the two networks, the mechanical properties and thermal resistance exhibit higher values when 80/20 （w/w） FKM and NBR is blended and respectively cured simultaneously. The co-continuous morphology of the IPNs in the blends of 80/20 （w/w） FKM/NBR is found by transmission electron microscopy （TEM）, the differential scanning calorimetry （DSC） determination shows that the blends of 80/20 （w/w） FKM/NBR have better compatibility, and the glass transition temperature of the elastomer is -21.5 ℃.

AN EPOXY/(METHYL METHACRYLATE)INTERPENETRATING POLYMER NETWORK FOR NONLINEAR OPTICS

An interpenetrating polymer networks (IPN) consisting of an epoxy-based polymer network and a polymethyl methacrylate network were synthesized and characterized. The IPN showed only one T-g, and hence a homogeneous-phase morphology was suggested. The second-order nonlinear optical coefficient (d(33)) of the IPN was measured to be 1.72 X 10(-7) esu. The study of NLO temporal stability at room temperature and elevated temperature (100 degrees C) indicated that the IPN exhibits a high stability in the dipole orientation due to the permanent entanglements of two component networks in the IPN system. Long-term stability of second harmonic coefficients was observed at room temperature for more than 1000 h.

Preparation of Semi-interpenetrating Polymer Network of Silicon Rubber and Poly(methyl methylacrylate) Using Supercritical CO_2

The heterogeneous free-radical polymerization of methyl methylacrylate (MMA) and divinylbenzene (DVB) as cross-linker within supercritical carbon dioxide-swollen silicon rubber (SR) has been studied as an approach to preparing semi-interpenetrating polymer network (semi-IPN) of SR and poly(methyl methylacrylate) (PMMA). The SR/PMMA semi-IPNs were characterized by scanning electron microscopy (SEM) and dynamic mechanical analyzer (DMA).