Biocompatible Catechol-Functionalized Cellulose-Based Adhesives with Strong Water Resistance

Numerous traditional adhesives have good adhesion in dry environments. However, non-environmental-friendliness and poor water resistance largely limit their practical applications. To prepare biocompatible adhesives with strong water resistance and adhesion strength, in this paper, catechol-functionalized cellulose-based adhesive polymers are synthesized by grafting N-(3,4-dihydroxyphenethyl)methacrylamide and methyl methacrylate onto cellulose chain through atom transfer radical polymerization (ATRP). The successful synthesis of the catechol-functionalized cellulose-based adhesive polymers is confirmed by FTIR and ¹H NMR. The different characteristics of the adhesive polymers, such as thermal stability, swelling ratio, biocompatibility, and adhesion strength are investigated. Strong water resistance on various substrates is realized in underwater environment for the catechol-functionalized cellulose-based adhesive with addition of Fe³⁺. The adhesion strength and thermal stability are enhanced when the catechol content is increased. The adhesive with catechol content of 25.4% shows the adhesion strength of 0.45 MPa for iron substrate in underwater environment. In addition, the adhesive with addition of Fe³⁺ exhibits excellent adhesion in dry environment, with maximum adhesion strength of 3.50 MPa for iron substrate. The cell culture test shows that the adhesive polymers have excellent biocompatibility. The biocompatible adhesives with strong water resistance have potential application in electronic, wood, and building fields.     

Reusable dry adhesives based on ethylene vinyl acetate copolymer with strong adhesion

This work proposed the design and fabrication method for T-shaped dry adhesives based on stretchable ethylene-vinyl acetate (EVA) copolymer, with strong normal adhesion strength up to 70 N cm⁻². As fabricated adhesives based on the inexpensive soft replication process have comprehensive advantages including easy demolding applicable for various curable materials; self-cleaning characteristic based on excellent nonwetting characteristics to both water and oil; reversible adhere/detach cycling for reusability. The flexible and transparent EVA dry adhesive films were readily fabricated to be novel dry-adhesive coatings decorated on various substrates and shapes. We also explored the adhere and detach mechanism for the significantly enhanced adhesion of T-shaped EVA microstructures, which indicated the increased contact area and the friction dissipation between the undercut and the substrate contribute to the adhesion enhancement, while the excellent elastic deformation of EVA may play an important role for adhesion enhance during the pulling-off process. These results showed the great potential of high-performance T-shaped EVA-based polymer dry adhesives for practical applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47296.     

Polysaccharide‐based artificial extracellular matrix: Preparation and characterization of three‐dimensional,macroporous chitosan and chondroitin sulfate composite scaffolds

Scaffold‐guided tissue engineering based on synthetic and natural occurring polymers has gained much interest in recent years. In this article, the development of a polysaccharide‐based artificial extracellular matrix (AECM) is reported. Three‐dimensional, macroporous composite AECMs composed of chondroitin sulfate (ChS) and chitosan (Chito) were prepared by an interpolyelectrolyte complex/lyophilization method. The ChS–Chito composite AECMs were crosslinked with glutaraldehyde and calcium ions (Ca²⁺) and cocrosslinked with N,N‐(3‐dimethylaminopropyl)‐N′‐ethyl carbodiimide (EDC) and N‐hydroxysuccinimide (NHS). The crosslinking reactions were examined with Fourier transform infrared analysis. Glutaraldehyde and Ca²⁺ crosslinked with Chito and ChS, respectively, to produce different types of ChS–Chito semi‐interpenetrated networks. In contrast, EDC/NHS crosslinked with both Chito and ChS to produce ChS–Chito connected networks. In physiological buffer solutions, the Ca²⁺‐crosslinked ChS–Chito composite AECMs showed a lower swelling ratio than their EDC/NHS‐ and glutaraldehyde‐crosslinked counterparts. The ChS–Chito composite AECMs showed excellent antibacterial capability and biocompatibility according to the results of the in vitro antibacterial test and cytotoxic assay. This result suggested that the ChS–Chito composite AECMs might be a potential biomaterial for scaffold‐guided tissue‐engineering applications. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Adhesive based on micellar lupin protein isolate exhibiting oxygen barrier properties

In order to minimize the utilization of non‐renewable fossil resources, novel polymer sources for food packaging are being investigated. Micellar Lupin Protein (MLP), produced by dilution precipitation has great potential as functional laminating adhesive due to its high adhesion‐ and oxygen‐barrier properties. Formulations of MLP are used as laminating adhesive between high density‐polyethylene foil and paper as well as coating for poly(ethylene terephthalate) foil. The application of glycerol, sorbitol and combinations thereof as plasticizers are being investigated. Adhesive behavior as well as oxygen‐ and water vapor barrier properties were tested. The addition of both plasticizers enabled the preparation of processable coatings showing coherent and homogeneous morphology with improved adhesive behavior and oxygen barrier. When using sorbitol oxygen permeation coefficients of 0.93 cm³ (STP) 100 µm m^?2 d^?1 bar^?1 were achieved. The laminates containing only sorbitol provided adhesion properties comparable to standard polyurethane laminates with cohesion failure in 100% of the by T‐Peel‐Test examined cases. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46383.     

Underwater polyurethane adhesive with enhanced cohesion by postcrosslinking of glycerol monomethacrylate

Polyurethane (PU) has been widely used as a glue in various areas. However, adhesion in the presence of water is greatly impeded and results in most synthetic adhesive failure. In this study, we designed and synthesized a novel PU construction; underwater PU adhesives were created by the incorporation of synthetic glycerol monomethacrylate (GMA). Furthermore, the urethane structure helped the adhesive eliminate the interfacial water barrier through interactions that were stronger than hydrogen bonding, and GMA as a crosslinking agent was used to generate post‐covalent‐crosslinking networks through radical polymerization. This enhanced the cohesion so the diffusion of water molecules could be overcome. Fourier transform infrared spectroscopy, thermogravimetric analysis, underwater adhesion measurements, and tensile tests were used to characterize the chemical and mechanical properties of the as‐obtained adhesive. This led to an adhesive with a better mechanical strength and interfacial adhesion in water, and the results show that the mechanical properties (tensile strength, Young's modulus, and tensile elongation) of the GMA–PU adhesive were higher than those of the pure PU. As for the 4% GMA, the tensile strength was enhanced by 24.3% and the elongation was enhanced by 125.23% over those of the pure PU. This confirmed that the incorporation of GMA into the PU matrix indeed induced increasing cohesion, and the sample's adhesive strength was 21.19 ± 3.9 MPa; this indicated a superior adhesive strength over that of the pure PU. In addition, we can foresee that underwater adhesion will play an important role in prospective surgery and engineering areas. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46579.     

Monomers for adhesive polymers: 11. Structure–adhesive properties relationships of new hydrolytically stable acidic monomers

The synthesis of six new hydrolytically stable acidic monomers is described. Those monomers are N,N‐disubstituted acrylamides bearing either a phosphonic acid group or a diphosphonic acid group. They were fully characterized using ¹H NMR, ¹³C NMR and ³¹P NMR spectroscopy and high‐resolution mass spectrometry. The copolymerization of each acidic monomer with N,N′‐diethyl‐1,3‐bis(acrylamido)propane was investigated using photo‐differential scanning calorimetry. Self‐etching enamel–dentin adhesives were formulated and evaluated in terms of both dentin and enamel adhesion. The influence of the monomer structure (nature of either the spacer or the acidic group, nature of the acrylamide substitution) on the adhesive properties is discussed. The adhesives based on 10‐(N‐ethylacrylamido)decylphosphonic acid and 10‐(N‐methylacrylamido)decylbisphosphonic acid are able to achieve a strong bond between a dental composite and both dentin and enamel. © 2013 Society of Chemical Industry     

A polyurethane‐based nanocomposite biocompatible bone adhesive

A novel polyurethane‐based foam‐like adhesive reinforced with nanosized hydroxyapatite (HA) particles was developed and investigated for bone‐to‐bone bonding applications in terms of mechanical adhesion and biocompatibility. The adhesive has a hierarchical structure with HA particles at the nanoscale level and pores at the micro‐scale level. This adhesive was tested mechanically in the three principal loading modes anticipated: shear, tension, and compression. Standard testing procedures were used when available. Tensile strength of primed adhesive showed a four‐fold increase in adhesion on unmodified bone and a nearly two‐fold increase in adhesion to primed bone as compared with the conventional bone cement. Biocompatibility was initially assessed in vitro using cell culture tests, which showed positive interaction with the adhesive. Then, a second biocompatibility test was performed using Xenopus laevis limbs to assess an in vivo response. The results indicated that the adhesive material produces a normal response consistent with control specimens. However, long‐term observations and tests with additional species are needed to demonstrate full biocompatibility. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2013     

Surface modification using bio‐inspired adhesive polymers based on polyaspartamide derivatives

The catechol functional group of dopamine (3,4‐dihydroxyphenethylamine) has the ability to form strong adhesive bonds to inorganic and organic surfaces in aqueous environments. In this study, novel adhesive polyaspartamides containing catechol pendant groups were synthesized from polysuccinimide through successive aminolysis reactions with quantitative dopamine and ethylenediamine. The adhesion and crosslinking of dopamine‐modified polyaspartamide in aqueous alkaline media was used successfully to modify the surface of various materials (including synthetic polymers, metals, metal oxides, ceramics) using a simple immersion method. Contact angle measurements, SEM and X‐ray photoelectron spectroscopy of the modified surfaces were used to verify the surface coating on a variety of materials with very different inherent wetting properties. These novel biocompatible polymers have potential industrial and biomedical applications as adhesives or coating materials for functional surface modification. Copyright © 2011 Society of Chemical Industry     

Dimethylarginine‐Dimethylaminohydrolase‐2 (DDAH‐2) Does Not Metabolize Methylarginines

Free endogenous methylarginines, N^ω‐monomethyl‐L ‐arginine (L ‐NMMA) and N^ω,N^ω′‐dimethyl‐L ‐arginine (ADMA), inhibit NO synthases (NOSs) and are metabolized by dimethylargininedimethylaminohydrolase (DDAH). A postulated metabolism has been shown several times for DDAH‐1, but the involvement of DDAH‐2 in the degradation of ADMA and L ‐NMMA is still a matter of debate. Determination of the isoform‐specific DDAH protein expression profiles in various porcine tissue types shows a correlation of DDAH activity only with DDAH‐1 levels. DDAH activity (measured as L ‐citrulline formation from the conversion of methylarginines and alternative DDAH substrates) was detected in DDAH‐1‐rich porcine tissue types, that is, kidney, liver, and brain, but not in DDAH‐2‐rich porcine fractions, that is, spleen and thyroid. Furthermore, several ex vivo studies showed DDAH activity to be important for L ‐citrulline formation in porcine tissue and indicated the absence of an endogenous DDAH inhibitor in porcine tissue. This study provides new insights into tissue distributions as well as substrate selectivity for both DDAH isoforms. Although DDAH‐1 is known to metabolize the endogenous NOS inhibitors L ‐NMMA and ADMA, a physiological function for DDAH‐2 has yet to be determined. Hence, determining DDAH activity by methylarginine conversion is not suitable for analyzing isoform selectivity of DDAH‐1 inhibitors as postulated.     

Study on a new kind of polypropylene‐graft‐ polystyrene: Preparation and application

A novel synthetic route for preparing polypropylene‐graft‐polystyrene (PP‐g‐PSt) was set up. With this synthetic route, a series of PP‐g‐PSt copolymers containing different percentages of polystyrene chain were synthesized, based on the different reactivities of two kinds of C? C double bonds on 4‐(3‐butenyl) styrene. Characterization data, including ¹H‐NMR, ¹³C‐NMR, GPC, and DSC, demonstrated that the graft copolymers were all very pure. Furthermore, it was also attempted to use this new kind of propylene–styrene graft copolymer as a compatibilizer. DMA and SEM results illustrated that the PP‐g‐PSt obtained is an efficient compatibilizer for the polypropylene–polystyrene blend. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 314–322, 2004     

Crosslinkable deoxidizing hybrid adhesive of epoxy–diacid for electrical interconnections in semiconductor packaging

For electrical interconnections in semiconductor packaging, epoxy‐based pastes have recently attracted considerable interest due to their excellent adhesion to various substrates and their reasonable electrical and mechanical properties, especially when combined with deoxidizing agents (to remove metallic oxides). Here, epoxy–diacid‐based hybrid pastes were examined to achieve a deoxidizing capability for eliminating Sn‐based solder oxides and adhesion between microchip and substrate as a one‐step process. Onset, exothermic peak and end temperatures of the reaction between epoxy and diacids were systematically probed using DSC, rheometry and Fourier transform infrared (FTIR) spectroscopy. The last moment of the adhesive reaction during heating substantially enhanced the thermal and mechanical properties of the epoxy–diacid adhesive despite the absence of exothermic enthalpy detected by DSC. The glass transition temperature (T_g) and Young's modulus gradually decreased as a function of aliphatic chain length of diacids except when the length was extremely short and voids were produced. Soldering (wetting) and deoxidizing capabilities of the hybrid adhesive were observed via optical microscopy and FTIR. The correlation between the reaction, T_g, conversion and viscosity was also investigated. Lastly, complete wetting and electrical interconnection with good mechanical robustness were achieved for a commercial chip/substrate set by flip‐chip bonding. © 2018 Society of Chemical Industry     

Influence of adhesion on random loose packings of binary microparticle mixtures

Binary adhesive packings of microspheres with certain size ratios are investigated via a 3‐D discrete‐element method specially developed with adhesive contact mechanics. We found a novel phenomenon that the packing fraction of the binary adhesive mixtures decreases monotonically with the increase of the amount of small components. It was further divulged that this behavior results from the competition between a geometrical filling effect and an adhesion effect. The positive geometrical filling effect only depends on the size ratio, while a dimensionless adhesion parameter Ad is used to characterize the negative adhesion effect, which comes to its maximum at Ad ≈ 10. Structural properties, including contact network, partial coordination number, radial distribution function, and angular distribution function, are analyzed to give a better understanding of such adhesive binary packings. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4296–4306, 2017     

Surface charge of erythrocytes and lactobacilli S. thermophilus and their intercellular adhesion depend on the concentration of bivalent cations

We propose a simple and accessible model of lactobacilli adhesion to human erythrocytes. The influence of bivalent cations on the surface charge of erythrocytes and lactobacilli Streptococcus thermophilus and their adhesive interaction has been investigated. We have shown that, despite the seemingly similar unidirectional effect of Ca²⁺ and Mg²⁺ cations, the cause of decreased adhesion lactobacilli S. thermophilus to human erythrocytes differ. While Ca²⁺ ions affect the surface charge of erythrocytes, not changing it in S. thermophilus, Mg²⁺ ions, conversely, affect the surface charge of lactobacilli and do not change it in erythrocytes. Our results confirm our proposition that in this case, the bivalent cations affect the second irreversible stage of adhesion process, but not the physical interactions during the first reversible stage.     

Environmental effects on the adhesion properties of nanostructured epoxy‐silica hybrids

A nanostructured epoxy‐silica hybrid based on epoxy systems with interpenetrating silica domains was designed for a possible use as a structural adhesive for civil engineering applications. Silica domains were obtained in situ during the curing of the thermosetting matrix by means of the sol‐gel process, which was able to chemically bind the organic phase with the inorganic one. To assess the ability of the developed epoxy‐silica hybrid system of overcoming some of the well known deficiencies of conventional epoxy adhesives used in civil engineering field, the environmental effects on the adhesion properties of these novel systems were investigated. First, flexural tests were undertaken on cast epoxy‐silica specimens to determine the mechanical properties of the nanostructured adhesive when exposed to different environmental conditions, that is, moderate temperature or immersion in water. For comparison purposes, a control sample of epoxy resin, representative of a commercially available adhesive, was tested after the same exposure regimes. In order to assess their durability in service, concrete/concrete joints, bonded or with the hybrid epoxy‐silica or with the control epoxy adhesive, were exposed to the same environmental conditions and subjected to adhesion tests according to the “slant shear test.” The results obtained on both cast specimens and concrete/concrete adhesive joints proved the significantly better retention of properties of the nanostructured organic–inorganic adhesive compared to the control resin after exposure to moderate temperature or immersion in water. This constitutes a distinct advantage of the hybrid system over the corresponding conventional epoxy resins cured at ambient temperature for civil engineering applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42514.     

Enhanced adhesion force based on microphase separation induced by complexation of ferric ions and polyurethane matrix

Waterborne polyurethane elastomer (WPU) has been widely used as a glue, but it still has some drawbacks, including a long cure time and weak adhesive force. In order to overcome these drawbacks, a new composite [PU/ferric ion complexation (Fe/PU)] with high adhesive strength was successfully prepared using ferric ion (Fe³⁺) as a complexing agent. Fourier transform infrared spectroscopy, differential scanning calorimetry, dynamic mechanical analysis, and tensile testing were used to characterize the chemical structure and mechanical properties of the as‐obtained composites. Introduction of the ferric ion induces a certain degree of microphase separation, resulting in better mechanical strength and interfacial adhesion. The mechanical properties of the PU composite with ferric ions are higher than that of pure PU. The adhesive strength of the 25%‐Fe/PU composite is 32.46 ± 3.1 MPa, exhibiting superior adhesive strength. The tensile strength was enhanced 34%, and the elongation was enhanced 23.6% compared to pure PU. Furthermore, the Fe/PU composite, coordinated with ferric ions, exhibits an enhanced storage modulus and reduced loss coefficient compared to PU. We can foresee that Fe/PU composites will play an important role in the building and engineering areas. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46069.     

Strength of Epoxy/Glass Interfaces after Hygrothermal Aging

The stability of epoxy/glass interfaces subjected to hygrothermal aging was assessed using a fracture-mechanics approach. An epoxy system consisting of diglycidyl ether of bisphenol F cured with 2-ethyl-4-methyl-imidazole was bonded to borosilicate glass adherends that were treated with various types of adhesion promoters to provide a variety of interfaces. Adhesive strength was measured under dry, as-processed conditions and as a function of exposure time to an 85°C/85% relative humidity (RH) environment. As expected, the strain-energy-release rate, G _c , dropped significantly with aging time for the bare epoxy/glass interface. The drop in G _c is assumed to be due to a loss of interfacial forces. The use of two silane-based adhesion promoters, 3-aminopropyltriethoxysilane (APS) and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (ECH) resulted in improved adhesive strength both before and after hygrothermal aging. The improvement in adhesive strength can be explained by the introduction of chemical bonds at the interface. The drop in G _c is assumed to be due to a loss of interfacial forces and hydrolysis of siloxane bonds. In addition to the use of organosilane-based adhesion promoters, a series of polyhydroxyaminoethers (PHAE) thermoplastic adhesive resins was also investigated as potential adhesion promoters. It was found that 2% PHAE in Dowanol® PM, a hydroxyl-group-containing solvent, was the best system for the PHAE-based adhesion promoters. Interestingly, both the acetic acid concentration in the solvent and maleic anhydride content in the PHAE resin were shown to affect the adhesive strength.     

Synthesis and swelling behaviors of semi‐IPNs superabsorbent resin based on chicken feather protein

A novel chicken feather protein‐g‐poly (potassium acrylate)/polyvinyl alcohol (CFP‐g‐PKA/PVA) semi‐IPNs superabsorbent resin (SAR) based on feather protein, acrylic acid (AA), and polyvinyl alcohol (PVA) was synthesized by graft copolymerization and semi‐interpenetrating technology. The results from FTIR, SEM, and TGA analysis showed that both CFP and PVA reacted with PKA during the polymerization process. The effects of AA, PVA, initiator and crosslinker content on water absorbency of semi‐IPNs SAR were studied. The swelling behavior in various pHs and saline solutions were also investigated. The water absorbency of SAR reached the maximum at pH = 6. The effect of the five cations on swelling had the following order: Al³⁺ > Ca²⁺ > Mg²⁺ > K⁺ > Na⁺. The highest water absorbency in distilled water and 0.9 wt % NaCl solutions were 714.22 and 70.08 g g^?1, respectively. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39748.     

Metal adhesive properties of polyamides having the 2,3‐bis(1,4‐phenylene)quinoxalinediyl structure

Polyamides were synthesized by interfacial polycondensation of 2,3‐bis(4‐chloroformylphenyl)quinoxaline (BCFPQ) and several aliphatic diamines using a phase transfer catalyst, and their adhesive property for stainless steel was investigated. The inherent viscosity of the obtained polyamides ranged from 0.37 to 1.24 dL g⁻¹. The glass transition temperatures of the polyamides ranged between 154 and 201°C, and their thermal decomposition temperatures were above 450°C. The polyamides were soluble in several organic solvents, including m‐cresol, N‐methyl‐2‐pyrrolidone (NMP), and formic acid. The adhesive property for stainless steel was examined by a standard tensile test. One member of the series, polyamide P8, derived from BCFPQ and 1,8‐octanediamine, displayed high tensile strength with values of 232 kgf cm⁻² at 20°C, 173 kgf cm⁻² at 120°C, and 137 kgf cm⁻² at 180°C. Thus, the tensile strength of P8 decreased at 180°C, but the decrease was much smaller than that of an epoxy resin in wide use as a metal adhesive. Heat distortion temperature, measured by thermal mechanical analysis, of P8 was 191°C. This suggested that P8 possessed high thermal resistance in metal adhesives. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1366–1370, 1999     

Soft and Hard Adhesion

The force needed to pull a cylindrical stud from a soft elastomeric film depends on their elastic and geometric properties. For a rigid stud and a thick elastomeric film, the pull-off stress (σ) depends on the elastic modulus (E) of the film and the radius (a) of the stud as σ ～ (E/a)^1/2 (soft adhesion). However, when the film is very thin, the pull-off stress is significantly higher than the case with thick films, and its value depends on the elastic modulus and the thickness (h) of the film as σ ～ (E/h)^1/2 (hard adhesion). Here, we study the pull-off behavior of a soft cylindrical stud, one flat end of which is coated with a high modulus thin baseplate. As the flexural rigidity of this baseplate is varied, we observe the transition between the two types of adhesion. We present a simple physical interpretation of the problem, which could be of value in understanding various biofouling and adhesive situations.