Surface properties of polyurethane powder lacquers modified with polysiloxane‐methacrylic core‐shell nanoparticles

Non‐ and core‐shell nanoparticles‐containing polyurethane‐based powder coating systems, crosslinked with allophanate bonds containing polyisocyanates were examined. The surface structure of the powder coatings were investigated with a confocal microscopy and polarized optical microscopy (POM) using reflected light. The three‐dimensional surface topography and the values of surface roughness were determined. The surface structure was correlated with the chemical structure of the coatings and macroscopic surface behavior: surface free energy and gloss. These experimental results led to a better understanding of the development of surface topography and morphology and provide valuable information for the development of new polyurethane powder coating systems. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

pH sensitive functionalized hyperbranched polyester based nanoparticulate system for the receptor-mediated targeted cancer therapy

The aim of this study is to develop a novel folic acid conjugated, DL-lysine modified, PEGylated, the 3rd generation hyperbranched polymer (HBP-PEG-Lys-FA) for use in receptor-mediated therapy. 5-fluorouracil, model anti-cancer drug, loaded nanoparticles were found an average size of 177?nm with loading efficiency of 23.18%. In vitro drug release studies demonstrated that nanoparticles showed pH-dependent release. HBP-PEG-Lys-FA were efficiently taken up by HeLa cells and specificity of targeted nanoparticles to folate receptors of cells was proved. It was concluded that the HBP-PEG-Lys-FA nanoparticles can provide an advantage on delivering of the drug efficiently into the cytosol for cancer therapy.     

Surface‐modified silica nanoparticles for reinforcement of PMMA

Polymethyl methacrylate (PMMA) was introduced onto the surface of silica nanoparticles by particle pretreatment using silane coupling agent (γ‐methacryloxypropyl trimethoxy silane, KH570) followed by solution polymerization. The modified silica nanoparticles were characterized by Fourier‐transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). Sedimentation tests and lipophilic degree (LD) measurements were also performed to observe the compatibility between the modified silica nanoparticles and organic solvents. Thereafter, the PMMA slices reinforced by silica‐nanoparticle were prepared by in situ bulk polymerization using modified silica nanoparticles accompanied with an initiator. The resultant polymers were characterized by UV–vis, Sclerometer, differential scanning calorimetry (DSC). The mechanical properties of the hybrid materials were measured. The results showed that the glass transition temperature, surface hardness, flexural strength as well as impact strength of the silica‐nanoparticle reinforced PMMA slices were improved. Moreover, the tensile properties of PMMA films doped with silica nanoparticles via solution blending were enhanced. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Gold‐nanoparticle‐decorated thermoplastic polyurethane electrospun fibers prepared through a chitosan linkage for catalytic applications

Thermoplastic polyurethane (TPU)‐electrospun‐fiber‐mat‐supported gold catalysts were prepared by the adsorption of gold nanoparticles (AuNPs) onto a TPU electrospun fiber mat after functionalization with chitosan (CS) by a dip‐coating method. The mechanism for the adsorption of AuNPs was electrostatic interaction between the positive charge of CS (? N ) and the negative charge of the AuNP surface (? COO^?) and coordination between the amine groups of CS and gold. The mat was crosslinked with glutaraldehyde vapor to strengthen the adhesion between the CS coating and TPU fibers after the adsorption of AuNPs. The catalytic activity of the supported gold catalyst was evaluated with the reduction of 4‐nitrophenol by NaBH₄ to demonstrate the excellent catalytic performance and its reusability for at least 10 cycles without a loss in activity. The rate constant increased with both an increase in the amount of supported catalyst and an increase in the ratio of the mat surface area to AuNP within the investigated scope. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133 , 44336.     

Surface‐enhanced fluorescence of in situ synthesized polysilanesilver nanoparticles

To produce surface plasmons, silver nanoparticles are synthesized in situ in a pseudo‐template system based on polyhydrosilanes. Adsorption on the silver nanoparticle surface produces a thin layer of polymer with properties different from those of bulk polysilane. The metal‐adsorbed polymer layer serves as a spacer between the polysilane fluorophore and the plasmonic nanoparticle. This prevents quenching of the polysilane emission and leads to a strong surface‐enhanced fluorescence through coupling of surface plasmons having a resonance frequency that matches the emission frequency of the polymeric emitter. Copyright © 2012 Society of Chemical Industry     

Monoclonal antibody‐targeted polymeric nanoparticles for cancer therapy – future prospects

Although combination therapy for cancer utilising monoclonal antibodies in conjunction with chemotherapeutic drugs has resulted in increases in 5 year survivals, there nevertheless remains significant morbidity and mortality associated with systemic delivery of cytotoxic drugs. The advent of living radical polymerisation has resulted in complex and elegant nanoparticle structures that can be engineered to passively target a drug payload for cancer treatment. This presents a therapeutic modality whereby biodistribution and consequently systemic toxicity can be reduced, while focusing drug delivery to the tumour site. Nanoparticle delivery can be enhanced by attachment of a targeting monoclonal antibody fragment to facilitate tumour cell uptake through endocytosis, and so increase therapeutic efficacy. In this way, monoclonal antibodies can be supercharged by carrying a payload consisting of a cocktail of conventional chemotherapeutic drugs and siRNA. This review will focus on antibody‐targeted polymeric nanoparticles to cancer cells, and methods and technologies for synthesising such antibody‐targeted nanoparticles. The review is confined to polymeric‐based nanoparticles as these offer some advantages over liposomal nanoparticles and may circumvent some of the pitfalls in nanomedicine. Development of these antibody based polymeric nanoparticles and future directions for therapy are highlighted in this review. © 2014 Society of Chemical Industry     

New polyether diols as flame retardants for polyurethane: Derivatives of epoxy‐functionalized phosphonates and phosphates

Phosphorus‐containing epoxides were used to generate several oligomeric polyether diols, which were in turn utilized in the preparation of model polyurethane (PU) samples, either as comonomers in the polymerization ( Prep samples) or solvent blended into a priori prepared PU ( Blend samples). The resultant samples were evaluated for heat release reduction potential using microcombustion calorimetry. Several variables were investigated in the oligomerization of the original epoxides, such as presence of initiator, epoxide comonomer, and solvent. The oligomer mixtures were thoroughly characterized, using NMR, mass spectrometry (MS), elemental analysis, and viscosity measurements. The final PU Prep samples were carefully analyzed to demonstrate and evaluate the degree of chemical incorporation of the polyether diols into the PU main chain. Results from the heat release studies demonstrated that incorporation of the phosphorus‐containing diol did lower flammability, but the structure of the original epoxide, as well as the oligoimerization conditions, had an effect on heat release reduction. The results are complex and require further study, but the phosphonate‐based materials showed greater heat release reduction potential, both in the form of Prep and Blend samples, especially in one case of a Blend sample, where a notable amount of intumescent char was formed.     

Flame retardant polyurethane elastomer nanocomposite applied to coal mines as air‐leak sealant

Polyurethane elastomer (PUE) was firstly applied to mining coal roadway as air‐leak sealant. It is very important for air‐leak sealants to possess the super mechanical properties and good flame retardant performance when applied to the coal‐rock mass with cracks. The reinforced and toughened PUE nanocomposites were obtained by adding surface modified TiO₂ and SiO₂ nanoparticles. The modified PUE was characterized in terms of morphology, structure, and thermal stability by field‐emission scanning electron microscopy (FESEM), X‐ray diffraction (XRD), infrared spectroscopy (IR), and thermogravimetric analysis (TGA). Its flame‐retardant performance and mechanical properties were also tested. The results showed that the surface modified nanoparticles were uniformly dispersed in the PUE matrix and enhanced its thermal stability and flame retardant performance. The dual effects of uniform dispersion of nanoparticles and hydrogen bonding between nanoparticles and PUE improved the mechanical properties of the composites. The PUE modified by nanoparticles was successfully applied to coal mines and showed great air‐leak sealing effect. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Application‐directed syntheses of surface‐functionalized organic and inorganic nanoparticles

An overview of the formation of inorganic and organic particles in emulsions is presented. The key aspect in these syntheses is the use of specially designed surface‐active components. Examples of synthesis‐driven approaches to various functional nanoparticles are illustrated. Surfmers based on isophthalic acid give access to particles for highly stabilized emulsions. Amphiphilic block copolymers as emulsifiers result in particles with excellent film‐forming properties or which are applicable as supports for metallocenes. Amphiphilic statistical copolymers are used for the compatibilization of inorganic nanoparticles in hybrid materials. Block and statistical copolymers are versatile stabilizers of non‐aqueous emulsions. In such systems nanoparticles obtained by either water‐sensitive monomers or catalysts can be realized. Surface functionalization with aliphatic or aromatic amines results in latex particles, which are suitable as supports for postmetallocenes or as flocculants in the papermaking process. In each area, the incorporation of the amphiphiles at the nanoparticle surface is not only important for the particle formation itself, but also decisive for the applicability of the particles. Copyright © 2007 Society of Chemical Industry     

Sorption of propylene and propane in polyurethane membranes containing silver nanoparticles

The preparation of a facilitated transport membrane of polyurethane (PU) containing silver nanoparticles is reported. The propylene and propane sorption was investigated aiming at the selective separation from C3s mixtures. The silver particles were photogenerated in situ into the polyurethane matrix using UV light radiation and silver triflate (AgCF₃SO₃) as precursor. The morphological properties of these membranes (PUAg) reveled great dispersion of silver particles, which size was smaller than 110 nm. The propylene solubility in PUAg resulted more than four times superior to the one for the pure PU membrane, revealing the high affinity between silver and propylene. Flory–Huggins theory was more accurate to describe the propylene sorption behavior in PUAg than Henry's model. The ideal solubility selectivity of PUAg membrane resulted 24.4, indicating that there is a good potential for an industrial application aiming at the separation of propylene/propane. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42916.     

Synthesis and properties of nanosilica‐reinforced polyurethane for grouting

A polyurethane/nanosilica (PU/SiO₂) hybrid for grouting was prepared in a two‐step polymerization using poly(propylene glycol) diols as the soft segment, toluene 2,4‐diisocyanate (TDI) as the diisocyanate, 3,3′‐dichloro‐4,4′‐diaminodiphenylmethane (MOCA) as the chain extender, and acetone as the solvent. The size and dispersion of nanosilica, the molecular structure, mechanical properties, rheological behavior, thermal performance, and the UV absorbance characteristic of the PU/SiO₂ hybrid were investigated by transmission electron microscopy (TEM), FTIR, mechanical tests, viscometry, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and UV spectroscopy. Nanosilica dispersed homogeneously in the PU matrix. The maximum values of mechanical properties such as tensile strength, elongation break, and adhesive strength showed an addition of nanosilica of about 2 wt %. Resistance to both high and low temperatures was better than with PU. And the UV absorbance of the PU/SiO₂ hybrid increased in the range of 290–330 nm with increasing nanosilica content. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4333–4337, 2006     

Synthesis of s‐triazine‐based hyperbranched polyurethane for novel carbon‐nanotube‐dispersed nanocomposites

s‐Triazine‐based hyperbranched polyurethanes (HBPUs) with different hard segments were synthesized by A₂ + B₃ approach. Various kinds of multiwalled carbon nanotube (MWNT) nanocomposites with HBPU were prepared to investigate an impact of hyperbranched polymer on dispersion of MWNTs in the polymer matrix and the resulting properties of nanocomposites. Synthesized HBPUs were characterized using FTIR and NMR measurements. The highly branched structures were found very effective in enhancing the pristine MWNT dispersion in the polymer matrix. As a result, the MWNT‐reinforced HBPU nanocomposites showed a steep increase in the yield stress and modulus and enhanced shape memory effect with an increase of hard segment and MWNT loading. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and properties of magnetic sensitive shape memory Fe3O4/poly(ε‐caprolactone)‐polyurethane nanocomposites

Fe₃O₄/poly (ε‐caprolactone)‐polyurethane (PCLU) shape memory nanocomposites were prepared by an in situ polymerization method. The thermal properties, magnetic properties, and shape memory properties of the nanocomposites were investigated systematically. The results showed that the Fe₃O₄ nanoparticles were homogeneously dispersed in the PCLU matrix, which ensured good shape memory properties of nanocomposites in both hot water and an alternating magnetic field (f = 45 kHz, H = 29.7 kA m^?1/36.7 kA m^?1). The nanocomposites started to recover near 40°C, which is slightly higher than body temperature. Thus, they would not change their deformed shape during the implanting process into the human body. Considering potential clinical applications, 45°C was chosen as shape recovery temperature which is slightly higher than 37°C, and the nanocomposites had high shape recovery rate at this temperature. With increasing content of Fe₃O₄ nanoparticles, the shape memory properties of the nanocomposites in an alternating magnetic field increased and the best recovery rate reached 97%, which proves that this kind of nanocomposites might be used as potential magnetic sensitive shape memory materials for biomedical applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2013     

Synthesis of palm oil‐based polyester polyol for polyurethane adhesive production

Palm oil‐based polyester polyol is synthesized by ring opening reaction on epoxidized palm olein by phthalic acid. The reaction is carried out in a solvent free and noncatalyzed condition with the optimal reaction condition at 175°C for 5 h reaction time. The physical state of the product is a clear bright yellowish liquid with low viscosity value of 5700–6700 cP at 25°C and pour point of 15°C. The chemical structure and molecular weight of the polyester polyol were characterized by FTIR, ¹H‐NMR, ¹³C‐NMR, and GPC. The optimal polyol with molecular weight of 36,308 dalton and hydroxyl value of 78.17 mg KOH/g sample was reacted with polymeric 4,4′‐methylene diphenyl diisocyanate (pMDI) at isocyanate index of 1.3 to produce polyurethane adhesive. The lap shear strength of the polyurethane adhesive showed two times higher than the commercial wood adhesives. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 39967.     

Characteristics of waterborne polyurethane/poly(N‐vinylpyrrolidone) composite films for wound‐healing dressings

For ideal wound‐healing dressings, a series of waterborne polyurethane (WBPU)/poly(N‐vinylpyrrolidone) (PVP) composite films (transparent film dressings) were prepared by in situ polymerization in an aqueous medium. Stable WBPU/PVP composites, which had a high remaining weight greater than 98.4%, were obtained. The maximum content of PVP for stable WBPU/PVP dispersions was found to be about 15 wt %. The water absorption (%) and equilibrium water content (%) of the WBPU/PVP composite films remarkably increased in proportion to the PVP content and the time of water immersion. The maximum water absorption and equilibrium water content of the WBPU/PVP composite films were in the range of 21–158 and 22–56%, respectively. The water vapor transmission rate of the WBPU/PVP composite films was in the range of 1816–2728 g/m²/day. These results suggest that WBPU/PVP composite films may have high potential as new wound‐dressing materials that provide and maintain the moist environment needed to prevent scab formation and dehydration of the wound bed. By a wound‐healing evaluation using a full‐thickness rat model experiment, it was found that a wound covered with a typical WBPU/PVP composite film (15 wt % PVP) was completely filled with new epithelium without any significant adverse reactions. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Functionally modified,melt‐electrospun thermoplastic polyurethane mats for wound‐dressing applications

The electrospinning of a polymer melt is an interesting process for medical applications because it eliminates the cytotoxic effects of solvents in the electrospinning solution. Wound dressings made from thermoplastic polyurethane (TPU), particularly as a porous structured electrospun membrane, are currently the focus of scientific and commercial interest. In this study, we developed a functionalized fibrillar structure as a novel antibacterial wound‐dressing material with the melt‐electrospinning of TPU. The surface of the fibers was modified with poly(ethylene glycol) (PEG) and silver nanoparticles (nAg's) to improve their wettability and antimicrobial properties. TPU was processed into a porous, fibrous network of beadless fibers in the micrometer range (4.89 ± 0.94 μm). The X‐ray photoelectron spectroscopy results and scanning electron microscopy images confirmed the successful incorporation of nAg's onto the surface of the fiber structure. An antibacterial test indicated that the PEG‐modified nAg‐loaded TPU melt‐electrospun structure had excellent antibacterial effects against both a Gram‐positive Staphylococcus aureus strain and Gram‐negative Escherichia coli compared to unmodified and PEG‐modified TPU fiber mats. Moreover, modification with nAg's and PEG increased the water‐absorption ability in comparison to unmodified TPU. The cell viability and proliferation on the unmodified and modified TPU fiber mats were investigated with a mouse fibroblast cell line (L929). The results demonstrate that the PEG‐modified nAg‐loaded TPU mats had no cytotoxic effect on the fibroblast cells. Therefore, the melt‐electrospun TPU fiber mats modified with PEG and nAg have the potential to be used as antibacterial, humidity‐managing wound dressings. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40132.     

Preparation and characterization of thermoplastic water‐borne polycarbonate‐based polyurethane dispersions and cast films

Stable water‐borne polyurethane dispersions (PUDs) were prepared from bifunctional aliphatic polycarbonate‐based macrodiol, 2,2‐bis(hydroxymethyl)propionic acid (DMPA), 1,6‐diisocyanatohexane, 1,4‐butanediol (BD), and triethylamine. Water‐borne dispersion particles are thus solely formed from self‐assembled linear PU chains. Both PUDs and PUD‐based films were characterized with regards to the concentration of DMPA (ionic species content) and BD (hard‐segment content). Average particle size of PUDs decreased and their long‐term stability increased with increasing DMPA and decreasing BD concentration. Functional properties of cast films made from PUDs are substantially influenced by the character of the original colloidal particle dispersions. The swelling behavior of the films, their surface morphology, and mechanical properties are more influenced by DMPA than BD contents. At DMPA concentrations higher than 0.2 mmol g^?1 of the solid mass of polyurethane, distinct self‐organization of individual nanoparticles into fibril‐like structures was detected by atomic force microscopy and scanning electron microscopy. PU films made from PUD containing high BD as well as high DMPA concentrations have the best utility properties namely sufficient tensile properties and a very low swelling ability. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42672.     

Fiber–matrix interactions in aramid‐short‐fiber‐reinforced thermoplastic polyurethane composites

The mechanical and dynamic mechanical properties of thermoplastic polyurethane (TPU) elastomers reinforced with two types of aramid short fibers, m‐aramid (Teijin‐Conex) and copoly(p‐aramid) (Technora), were investigated in this study with respect to the fiber loading. In general, both types of composites exhibited very similar stress–strain behaviors, except that Technora–TPU was stronger than Conex–TPU. This was primarily due to the intrinsic strength of the reinforcing fibers. Both types of fibers reinforced TPU effectively without any surface treatment. This could be attributed to good fiber–matrix interactions, which were revealed by the broadening of the tan δ peak in dynamic mechanical analysis. Furthermore, the morphologies of cryogenically fractured surfaces of the composites and extracted fibers, investigated with scanning electron microscopy, revealed possible polar–polar interactions between the aramid fibers and TPU matrices. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1059–1067, 2003     

High performance polyurethane composites with isocyanate‐functionalized carbon nanotubes: Improvements in tear strength and scratch hardness

A microwave‐assisted functionalization of carbon nanotubes (CNTs) with isocyanate groups allowed a reduction of functionalization time from 24 h to 30 min with no change in the degree of functionalization or in the nanotube characteristics. Polymer nanocomposites with enhanced mechanical properties were obtained because of the tailored interface by the covalent linkage between the surface‐modified multiwalled‐carbon nanotubes (MWCNTs) and an elastomeric polyurethane (PUE) matrix. The mechanical data revealed that the composite containing 0.25 wt % of MWCNT‐NCO showed an increase of 31% in tear strength and 28% in static toughness. A good adhesion between the matrix and individually dispersed nanotubes was observed in the scanning electron microscopy and transmission electron microscopy images. Nanoindentation and nanoscratch experiments were conducted to investigate the properties on the sub‐surface. An increase by a factor of 3 in the scratch hardness was observed for the composite with 0.50 wt % of MWCNT‐NCO with respect to the neat PUE. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44394.     

Preparation and application of phosphorous‐containing bio‐polyols in polyurethane foams

A bio‐polyol phosphonate acting as the polyol component in the preparation of polyurethane foam was synthesized from the liquefaction product of bagasse by the halogenation of the liquefaction product followed by the Michaelis–Arbuzov rearrangement. The FT‐IR spectra showed that phosphorus‐containing groups were introduced into the polyol chain. The data of the viscosity and the hydroxyl number suggested that the bio‐polyol phosphonate would be a good polyol component in the preparation of polyurethane foam. The limiting oxygen index of polyurethane foam containing bio‐polyol phosphonate varied in the range of 24–28, while that of polyurethane foam without bio‐polyol phosphonate was 23, demonstrating that the introduction of the phosphorus‐containing group into the polymer helped to improve the flame retardancy. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40422.