Synthesis,characterization, and in vitro biocompatibility study of novel disulfide cross‐linked hydrogels based on poly(amic acid)

In this study, novel disulfide cross‐linked hydrogels were designed and synthesized. First, ethylenediaminetetraacetic dianhydride reacted with butanediamine and amino‐terminated polyethylene glycol via N‐acylation reaction to give biocompatible poly(amic acid) (PAA) with pendant carboxyl groups; then, the amino groups of cystamine reacted with carboxyl groups of PAA to generate disulfide cross‐linked network polymer (PAA‐SS). Fourier transform infrared spectroscopy, ¹H nuclear magnetic resonance imaging, gel permeation chromatography with multiangle laser light scattering, potentiometric titration, rheology, hydrolytic degradation, morphology, porosity, and in vitro biocompatibility studies were used to qualitatively and quantitatively characterize the obtained polymers. The results indicated that the equilibrium swelling ratio of the PAA‐SS decreased with the increase in Rm. The PAA‐SS provided good mechanical strength to maintain their integrity, and the storage modules (G′) of the hydrogels can be adjusted by Rm. The PAA‐SS presented co‐continuum pores, and the pore size correlated with the cross‐linking degree. The degradation of PAA‐SS could be controlled by regulating the concentration of dithiothreitol. Particularly, the PAA‐SS possessed an excellent biocompatibility, as the average proliferating rate of osteoblasts on PAA‐SS was appreciably higher than that on PAA and glass coverslips. In conclusion, the above obtained results demonstrate that the performance of the PAA‐SS outbalance and facilitate the application in biomedical region, particularly in bone tissue regeneration. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40930.     

Synthesis and characterization of polyhydroxylated polybutadiene binding 2,2′‐thiobis(4‐methyl‐6‐tert‐butylphenol) with isophorone diisocyanate

A macromolecular hindered phenol antioxidant, polyhydroxylated polybutadiene containing thioether binding 2,2′‐thiobis(4‐methyl‐6‐tert‐butylphenol) (PHPBT‐b‐TPH), was synthesized via a two‐step nucleophilic addition reaction using isophorone diisocyanate (IPDI) as linkage. First, the ? OH groups of PHPBT reacted with secondary ? NCO groups of IPDI to form the adduct PHPBT‐NCO, then the PHPBT‐b‐TPH was obtained by one phenolic ? OH of 2,2′‐thiobis(4‐methyl‐6‐tert‐butylphenol) (TPH) reacting with the PHPBT‐NCO. The PHPBT‐b‐TPH was characterized by Fourier transform infrared spectroscopy, ¹H nuclear magnetic resonance (¹H‐NMR), ¹³C‐NMR, and thermogravimetric analysis, and its antioxidant activity in natural rubber was studied by an accelerated aging test. Influences of reaction conditions on the two nucleophilic reactions between ? OH group and ? NCO group were investigated. In addition, catalytic mechanism for the reaction between PHPBT‐NCO and TPH was discussed. The results showed that the adduct PHPBT‐NCO could be obtained by using dibutyltin dilaurate (DBTDL) as catalyst, and the suitable temperature and DBTDL amount were 35°C and 3 wt %, respectively. However, triethylamine (TEA) was more efficient than DBTDL to catalyze the reaction between PHPBT‐NCO and TPH because of steric hindrance effect. In addition, it was found that the thermal stability and antioxidant activity of PHPBT‐b‐TPH were higher than those of the low molecular weight antioxidant TPH. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40942.     

Poly(ethyleneterephthalate) glycolysates as effective toughening agents for epoxy resin

The potential of poly(ethyleneterephthalate) glycolysates toward improving the energy absorption characteristics of cycloaliphatic epoxy resins has been explored. Microwave‐assisted glycolytic depolymerization of PET was performed in the presence of polyether diols of different molecular weights. The obtained glycolysates were blended with epoxy, and their mechanical properties were studied under both quasi‐static and dynamic conditions. Significant improvements were observed, which were found to depend both on the amount as well as nature of glycolysate. Amine functionalities were introduced at the terminal positions of glycolysates to improve the compatibility between the two phases. The amine derivatives exhibited superior performance and the Mode I fracture toughness (K_IC) of epoxy increased by ～18% in optimized compositions, which is indicative of its improved notch sensitivity. Neat epoxy specimens fractured in a brittle fashion, but all the blends exhibited ductile failure, as evidenced by surface morphological investigations. The mechanical properties of epoxy blends prepared with analogous aliphatic polyols, both before and after amine functionalization, were also studied which clearly reveal the beneficial role of aromatic groups toward improving the toughness of the base cycloaliphatic epoxy resin without compromising on the material stiffness. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39941.     

Preparation and functional evaluation of agarose derivatives

A facile microwave‐assisted one‐pot synthesis of sodium carboxymethylagarose and calcium carboxymethylagarose from Gracilaria dura agarose (Ag) has been described. The process is user friendly, and the highest degree of substitution was obtained within 15 min compared with the conventional method, which requires more than 3 h. Solubility and gelling behavior of the modified Ag products were found to be dependent on degree of substitution of the products. The characterizations were done by using Fourier transform infrared spectroscopy, ¹H‐ and ¹³C‐nuclear magnetic resonance spectroscopy, thermogravimetric analysis, scanning electron microscopy, Inductively coupled plasma spectrophotometry (ICP), rheology, conductometer analysis, and DNA gel electrophoresis. These agarose derivatives were easily soluble in water and exhibited low thermal hysteresis, improved conductivity, and improved the DNA resolution ability of the parent G. dura Ag hydrogels. These hydrogels may have potential applications in the areas including electrochemical devices, microbiology, biomedical, and pharmaceuticals fields. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40630.     

Aqueous polyacrylate/poly(silicone‐co‐acrylate) emulsion coated fertilizers for slow nutrient‐release application

Waterborne polyacrylate/poly(silicone‐co‐acrylate) emulsions were synthesized to develop coated fertilizers. The effects of the n‐butyl acrylate (BA)/methyl methacrylate (MMA) ratio, vinyltriethoxysilane, and synthesis method on the water resistance, glass‐transition temperature, mechanical properties, and nutrient‐release profiles were investigated. The results show that miniemulsion polymerization with a BA/MMA ratio of 55:45 was the most suitable for slow nutrient‐release applications. Under these conditions, the preliminary solubility rate of the nutrient was about 3%, and the 30‐day cumulative nutrient release was 15% at 25°C. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40369.     

Cotton‐fabric‐grafted poly(N‐isopropyl acrylamide) initiated by ammonium peroxydisulfate

In this article, we report that thermoresponsive poly(N‐isopropyl acrylamide) (PNIPAAm) was successfully grafted onto a cotton fabric (CF) surface by free‐radical solution grafting polymerization; we obtained a thermoresponsive CF‐grafted PNIPAAm. This reaction system only contained four constituents: the monomer, solvent, initiator, and CFs. Ammonium peroxydisulfate was chosen as the initiator, and water was chosen as the solvent. A series of initiator concentrations and grafting polymerization temperatures were used in the experiments, and their effects on the grafting ratio (G) were also studied. Also, the effects of the G of CF‐g‐PNIPAAm on their corresponding thermoresponses was studied further. The structure of CF‐g‐PNIPAAm was characterized by Fourier transform infrared spectroscopy–attenuated total reflectance analysis and scanning electron microscopy analysis. The G of CF‐g‐PNIPAAm was measured by a gravimetric method. The thermoresponse of CF‐g‐PNIPAAm was characterized by modulated differential scanning calorimetry, water contact angle measurements, and wetting time measurements. The experiments manifested the following results: (1) the initiator concentration and grafting polymerization temperature both influenced G, (2) the grafted PNIPAAm covered the CF surface, (3) the CF‐g‐PNIPAAm showed thermoresponsive hydrophilicity/hydrophobicity, and (4) a relationship existed between the thermoresponse of CF‐g‐PNIPAAm and the corresponding G. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41193.     

Gradient and weather resistant hybrid super‐hydrophobic coating based on fluorinated epoxy resin

A weather resistant super‐hydrophobic coating that can offer good substrate adhesion and yet to be easily processed at large scale can be of practical use in emerging fields of self‐cleaning and anti‐icing paint, combing all these properties together remains challenging task. Here we describe a composite coating composed of a fluorinated epoxy resin emulsion with embedded in situ surface‐modified dual‐scale nano‐silica, which displayed durable super‐hydrophobicity and excellent adhesive strength. The as‐prepared coating possesses water contact angle of 158.6 ± 1°, sliding angle around 3.8 ± 0.2° which remain stable even under acidic/alkaline, heat/cool, and accelerated aging treatment. The results demonstrate that surface roughness had a micron‐ and nanometer scale distribution with increased particle loading beyond 40 wt %. Through quantitative comparison of surface Attenuated Total Reflection (ATR) with bulk FT‐IR transmission spectra, a gradient coating with surface enrichment of hydrophobic groups was determined. The air‐side fluorinated polysiloxane‐rich layer endows coating with weather‐resistance and ultra‐hydrophobicity while bottom epoxy resin layer enhances substrate adhesion. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40955.     

Synthesis,film morphology,and performance on cotton substrates of dodecyl/piperazine functional polysiloxane

A novel polysiloxane bearing dodecyl and epoxy side groups (DESO) was synthesized as an intermediate through hydrosilylation of polymethylhydrosiloxane with allyl glycidyl ether and 1‐dodecene. Then, dodecyl/piperazine functional polysiloxane (DPSO) was prepared through the reaction of N‐aminoethylpiperazine with DESO. The chemical structure of DPSO was characterized with FTIR and ¹H‐NMR spectroscopy and its application performance on cotton fabrics was studied. DPSO with dodecyl side groups gifted the treated fabrics with good wettability and whiteness compared with piperazine functional polysiloxane, while with a slightly reduced softness as well as thickening handle. Film morphology, orientation, and performance on cotton substrates of DPSO were investigated by scanning electron microscope, atomic force microscopy, X‐ray photoelectron microscope, and so on. Affected by the dodecyl side groups, DPSO formed relatively hydrophilic, macroscopically smooth but actually uneven films with many dodecyl side chain pillars on the treated substrate surfaces. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40186.     

β‐Cyclodextrin modified cationic acrylamide polymers for flocculating waste drilling fluids

In this article, the P(AM/A‐β‐CD/DMDAAC) is used as flocculant. The synthesis and characterization of the cationic polyacrylamide flocculant modified by β‐cyclodextrin have been studied in the early article. This article stresses its excellent flocculated performance and mechanism. In the flocculated process, the bridging flocculation played a dominant role. Through the flocculation experiments, it can be seen that the flocculating rate of the P(AM/A‐β‐CD/DMDAAC) on four solutions can go up to 93.4%, 89.7%, 85.1%, and 96.7%, respectively. As can be seen from experiment data, the flocculated property of P(AM/A‐β‐CD/DMDAAC) is superior to polyacrylamide and poly (dimethyl diallyl ammonium chloride). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40197.     

A thiol‐ene clickable hyperbranched polyester via a simple single‐step melt trans‐esterification process

Self‐condensation of AB₂ type monomers (containing one A‐type and two B‐type functional groups) generates hyperbranched (HB) polymers that carry numerous B ‐type end‐groups at their molecular periphery; thus, development of synthetic methods that directly provide quantitatively transformable peripheral B groups would be of immense value as this would provide easy access to multiply functionalized HB systems. A readily accessible AB₂ monomer, namely diallyl, 5‐(4‐hydroxybutoxy)isophthalate was synthesized, which on polymerization under standard melt‐transesterfication conditions yielded a peripherally clickable HB polyester in a single step; the allyl groups were quantitatively reacted with a variety of thiols using the facile photoinitiated “thiol‐ene” reaction to generate a wide range of derivatives, with varying solubility and thermal properties. Furthermore, it is shown that the peripheral allyl double bonds can also be readily epoxidized using meta‐chloroperoxybenzoic acid to yield interesting HB systems, which could potentially serve as a multifunctional cross‐linking agent in epoxy formulations. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40248.