Synthesis and characterization of a carboxyl‐terminated waterborne hyperbranched polymer and its coordination behavior with chromium(III)

Despite its irreplaceable position in the leather industry, chrome tanning has been listed in the procession of limitation. The serious environmental pollution caused by chrome tanning through the residual chrome it leaves in wastewater has attracted great attention. To improve the absorption of chrome and reduce chromium emission, a novel hyperbranched ligand was synthesized and characterized. The impact elements of the coordination process between the hyperbranched oligomer and Cr(III) was investigated, and the characteristics of the complex are also discussed. This hyperbranched oligomer had a low molecular weight (weight‐average molecular weight = 2125) and narrow molecular weight distribution (PDI = 1.21). The time required for the coordination process between the hyperbranched oligomer and Cr(III) was around 6 h, and the optimum pH was 4.0. Moreover, the complex exhibited alkali resistance and fair resistance to oxidation; this suggested that this developed hyperbranched ligand is a potential masking agent or tanning auxiliary for chrome tanning and will enable improvements in chromium absorption. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40117.     

Synthesis and characterization of hydroxy‐terminated polyether‐polydimethylsiloxane‐polyether (PE‐PDMS‐PE) triblock oligomers and their use in the preparation of thermoplastic polyurethanes

A series of hydroxy‐terminated polyether‐polydimethylsiloxane‐polyether (α,ω‐dihydroxy‐(PE‐PDMS‐PE)) ABA triblock oligomers were synthesized from silanic fluids and methyl polyallyloxide polyethers. The reaction was a one‐step solventless hydrosilylation reaction with chloroplatinic acid (CPA) catalyst in the presence of heat. These ABA oligomers were characterized via ¹H‐NMR, ¹³C‐NMR, ²⁹Si‐NMR, FT‐IR, and GPC to demonstrate that they exhibit a 100% linear ABA structure with a siloxane Si? O chain in the center and polyether ethylene oxide (EO)/propylene oxide (PO) chains on the two sides terminated by hydroxy groups. The triblock oligomers were used to form thermoplastic polyurethanes (TPUs) using two‐step solventless bulk polymerization. The investigation of triblock oligomers impact on TPUs mechanical properties, thermal performance, surface water repellency, and morphology performance were analyzed by Instron material tester, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), water contact angles (WCA), scanning electron microscope (SEM), and transmission electron microscope (TEM). DSC and TGA indicated that PE‐PDMS‐PE modified TPUs had a clear lower T_g under ?120°C and the temperature of 50% weight loss was improved from 280 to 340°C. PE‐PDMS‐PE–modified TPU did not have the marked reduction on mechanical properties than pure polyether produced TPU. Tensile strength was maintained at 13 MPa and elongation was maintained at 300%. SEM and TEM were used to investigate the copolymers’ morphology performance and found that all PO PE‐PDMS‐PE had a pseudo‐three phase separation. WCA analysis confirmed that PE‐PDMS‐PE–modified TPU had significantly improved hydrophobic performance because the silicone structure linked into TPU copolymers. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42521.     

Influence of an oligomer polyol and monomers on the structure and properties of core–shell polyurethane–poly(n‐butyl acrylate‐co‐styrene) hybrid emulsions

The free‐radical polymerization of alkenyl‐terminated polyurethane dispersions with styrene and n‐butyl acrylate was performed to obtain a series of stable polyurethane–poly(n‐butyl acrylate‐co‐styrene) (PUA) hybrid emulsions. The core–shell structure of the emulsions was observed by transmission electron microscopy, and the microstructure was studied by ¹H‐NMR and Fourier transform infrared spectroscopy. The effects of the poly(propylene glycol)s (number‐average molecular weights = 1000, 1500, and 2000 Da) and the mass ratios of polyurethane to poly(n‐butyl acrylate‐co‐styrene) (PBS; 50/50, 40/60, 30/70, 20/80, and 10/90) on the structure, morphology, and properties of the PUAs were investigated. The average particle size and water absorption values of the PUAs increased with increasing of PBS content. However, the surface tension decreased from 34.61 to 30.29 mN/m. PUA‐2, with a bimodal distribution, showed Newtonian liquid behaviors, and PUA‐3 showed a great thermal stability, fast drying characteristics, and excellent adhesion to packaging films. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43763.     

High elongation thermoplastic Polyester‐urethanes based on widely available diacid intermediates

A series of new α,ω‐dihydroxy terminated polyester oligomers are synthesized from the condensation reaction of various aliphatic diols with a mixture of diacids rich in 2‐methylglutaric acid, MGA, an abundant and well‐defined industrial product. Their adipic acid (AA)‐based counterparts are also prepared and the physico‐chemical properties of both types of polyols are thoroughly characterized. All these polyester polyols are then used to prepare segmented polyurethanes following a two‐stage process, by reacting them successively with 4,4′‐diphenylmethane diisocyanate, and 1,4‐butanediol. The resulting materials are then evaluated with respect to their thermal and dynamic or static mechanical properties. The observed characteristics and behaviors are quite similar between AA‐ or MGA‐based polyurethanes, except for the tendency of AA‐based samples to display partially crystallized soft domains. Such a phenomenon is prevented in MGA‐based samples because of the methyl side group, resulting in remarkably higher ultimate elongations for the new thermoplastic polyurethanes derived from MGA. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43410.     

Structure–property relationships of polycarbonate diol‐based polyurethanes as a function of soft segment content and molar mass

Segmented thermoplastic polyurethanes (PUs) have been synthesized with polycarbonate diol as soft segment and 4,4′‐diphenylmethane diisocyanate and butanediol as hard segment. Two different series employing two different soft‐segment molar mass, 1000 and 2000 g/mol, and by changing the hard‐segment content from 32 to 67% have been investigated with the aim to elucidate the effect of the different content variations on the properties. Morphological, thermal, and mechanical properties have been studied by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), wide angle X‐ray diffraction, atomic force microscopy, tensile and tear strength, hardness, and specific gravity tests. Properties have been explained from the standpoint of miscibility between hard‐ and soft‐segment microdomains of the tailored segmented PUs through an exhaustive analysis. FTIR, DSC, and DMA measurements revealed that miscibility between hard and soft microdomains increases as the molar mass of the macrodiol decreases. An increase in hard‐segment content entailed the formation of larger hard domains with higher crystallinity what results in superior mechanical properties such as higher tensile stress and tear strength, and hardness. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41704.     

Deblocking of the water‐soluble isophorone diisocyanate blocked by sodium bisulfite and its application

A water‐soluble and low stimulation sodium bisulfite blocked isophorone diisocyanate (IPDI) has been prepared. The blocking and deblocking of the blocked IPDI is observed by hot‐stage Fourier transform infrared (FTIR) spectrophotometer. The experimental results reveal that IPDI is successfully blocked by sodium bisulfite and the blocked IPDI can regenerate isocyanate groups when the temperature is higher than 80°C. Differential scanning calorimetry analysis indicates that blocked IPDI deblocks initially at around 85°C and reaches the maximum deblocking rate at 117°C. The blocked IPDI in liquid and solid states are stable after being stored for 12 months at room temperature. The blocked IPDI is used as curing agent for waterborne hydroxyl polyurethane, which has good adhesive performance and long pot life. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis and structural peculiarities of 1,1‐dimethylhydrazine‐based polyurethanes

Novel polyurethanes (PUs) based on poly(oxytetramethylene glycol), 4,4′‐methylenediphenyl diisocyanate, and 1,1‐dimethylhydrazine (DMH) were prepared. Stoichiometric (1 : 1) and nonstoichiometric (2 : 1 to 20 : 1) prepolymer/DMH ratios were studied. The number‐average molecular masses and possible structures of the obtained polymers were evaluated by potentiometric nonaqueous titration analysis of terminal groups, the Kieldal method (the evaluation of the nitrogen atom content), the aminolysis method, viscosimetry, IR spectroscopy, rheology, and small‐angle X‐ray scattering. Only in the case of the stoichiometric (1 : 1) ratio was a low‐molecular‐mass PU with a linear structure formed, whereas for all studied nonstoichiometric ratios, PUs with branched structures were formed. The level of hard and flexible block segregation increased with the increase in the prepolymer/DMH ratio. Dielectric results for the dynamic glass transition and water sorption measurements provided additional support to the structural studies. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis,structure, and properties of segmented carborane‐containing polyurethanes

Novel segmented carborane‐containing polyurethane (PUR 2–5) is synthesized from hydroxyl‐terminated carborane‐containing prepolymer (P3) as soft segment and isocyanate‐terminated carborane‐containing prepolymer (P5) as hard segment by different ratio of P3 and P5. The prepared carborane‐containing polyarylesters and polyurethanes (PURs) are characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR). Their mechanical properties and thermal stability are measured, while the dosage of carborane biphenol is 5–10 wt %, the tensile strength is up to 20 MPa, and thermal gravimetric analyzer (TGA) curves indicate that the carborane group effectively reduces the degradation rate of carborane‐containing polyurethane, which is fairly stable above 300°C and with char yield exceeding 40%. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42227.     

Synthesis and selected properties of polyurethanes with monodisperse hard segments based on hexane diisocyanate and three types of chain extenders

Poly(ethylene glycol) grafted octadecyl quaternized carboxymethyl chitosan (PEG-g-OQC) copolymers were synthesized to both improve the biocompatibility of OQC and form PEGylated cationic polymeric liposomes (CPLs), which composed of the mixture of OQC, cholesterol, and PEG-g-OQC. Structure of the copolymers was characterized by using Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance spectroscopy (¹H-NMR), and X-ray diffraction (XRD). The methyl tetrazolium (MTT) assay with L929 cell lines confirmed that PEGylation can decrease the cytotoxicity of OQC. PEGylated CPL nanoparticles (NPs) can be prepared by adding different weight ratio of PEG-g-OQC in the mixture. Paclitaxel was successfully incorporated into PEGylated CPLs with high drug encapsulating efficiency (>90%) and drug loading capacity (>15%). Physical stability experiment showed that paclitaxel-loaded PEGylated CPLs was stable with little change of particle size and size distribution in the condition of freeze-dried by adding mannitol or in high temperature and high pressure. Power or reagent of drug-loaded PEGylated CPLs showed a slow steady release profile for paclitaxel. These results show that PEG-g-OQC and CPLs have potential application as a drug delivery vehicle. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis and characterization of nanosilica/waterborne polyurethane end‐capped by alkoxysilane via a sol‐gel process

A novel method was used to synthesis nanosilica/waterborne polyurethane (WPU) hybrids by in situ hydrolysis and condensation of tetraethyl orthosilicate (TEOS) and/or 3‐aminopropyltriethoxylsilane bonding at the end of the WPU molecular chain. The hybrid was characterized by scanning electron microscopy, energy dispersive spectroscopy (EDS), transmission electron microscopy, Fourier transform infrared spectroscopy (FTIR), and X‐ray photoelectron spectroscopy (XPS). The results showed that the nanosilica/WPU hybrids with well‐dispersed nanosilica particles were synthesized, in which the particles had typical diameters of about 50 nm. In addition, XPS and FTIR analyses demonstrated that chemical interaction occurred between WPU and silica. The effects of TEOS on surface wettability, water resistance, mechanical strength, and thermal properties of the hybrid were also evaluated by contact angle measurements, water absorption tests, mechanical tests, and differential scanning calorimetry, respectively. An increase in advancing contact angles, water resistance, and tensile strength, as well as decrease in elongation at break and glass transition temperature, were obtained with the addition of TEOS. Water absorption decreased from 17.3 to 5.5%. The tensile strength increased to a maximum of 29.7 MPa, an increase of about 34%. Elongations at break of the hybrids decreased 191%. These results were attributed to the effects of the nanosilica and the chemical interaction between WPU and silica. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis,characterization, and UV‐curing properties of silicon‐containing (Meth)acrylate monomers

Eight different silicon‐containing (meth)acrylate monomers are synthesized by the substitution reaction of chlorosiloxanes with 2‐hydroxyethyl methacrylate or 2‐hydroxyethyl acrylate. Their molecular structures are confirmed by IR, ¹H‐NMR, and ¹³C‐NMR spectroscopic analyses. The effects of silicon content on the UV‐curing behavior, physical, surface, and thermal properties are investigated. The UV‐curing behavior is analyzed by photo differential scanning calorimetry. The surface free energy of the UV‐cured film is calculated from contact angles measured using the Lewis acid‐base three liquids method. The silicon‐containing (meth)acrylate monomers perform much better than traditional (meth)acrylate monomers on UV‐curing. The silicon‐containing monomers have higher final conversions and fast UV‐curing rates in photopolymerization. The surface free energy decreases with increasing silicon content, because silicon in the soft segment is transferred to the surface, producing a UV‐cured film; this is confirmed by X‐ray photoelectron spectroscopy measurements. All these advantageous properties enable these synthetic silicon‐containing monomers to perform better in applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Fluorene‐based click polymers: Relationship between molecular structure and nonlinear optical properties

To further understand the relationship between the polymer structure and nonlinear optical (NLO) property, in this article, three fluorene‐based triazole functional polymers with different linked chains were designed and controllably prepared by click chemistry method. The structures and properties of these polymers were characterized and evaluated with Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, ultraviolet spectroscopy, fluorescence spectra, dynamic state laser light scattering, thermogravimetric analysis, and NLO analyses. The results exhibited that the target polymers displayed good solubility, high thermal stability, and well NLO properties. The relationships between molecular structures and optical properties were investigated by both theoretical simulation and experimental results. It was found that the rigid conjugated linked chain between triazole and chromophore can effectively enhance the NLO properties of the resultant polymers. The suitable rigid and flexible groups in the triazole polymers will result in good thermal stabilities. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40878.     

Thermal and mechanical properties of polyisobutylene‐based thermoplastic polyurethanes

We investigated thermal and mechanical properties of thermoplastic polyurethanes (TPUs) with the soft segment comprising of both polyisobutylene (PIB) and poly(tetramethylene)oxide (PTMO) diols. Thermal analysis reveals that the hard segment in all the TPUs investigated is completely amorphous. Significant mixing between the hard and soft segments was also observed. By adjusting the ratio between the hard and soft segments, the mechanical properties of these TPUs were tuned over a wide range, which are comparable to conventional polyether‐based TPUs. Constant stress creep and cyclic stress hysteresis analysis suggested a strong dependence of permanent deformation on hard segment content. The melt viscosity correlation with shear rate and shear stress follows a typical non‐Newtonian behavior, showing decrease in shear viscosity with increase in shear rate. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 891‐897, 2013     

Synthesis and characterization of rubber‐seed‐oil‐based polyurethanes

Novel biobased polyurethanes were synthesized from rubber seed oil (RSO), a renewable resource. The RSO monoglyceride, together with xylene and hexamethylene diisocyanate (HMDI), was employed to synthesize the desired urethane‐based prepolymer with isocyanate (NCO)‐terminated end groups followed by curing. The degrees of crosslinking of the polyurethane after curing were assessed with their swelling behavior. The properties of the resulting polyurethanes were found to be dependent on the type of diisocyanate and their molar ratios to the RSO monoglyceride. The network structures, which were assessed through swelling studies, showed that networks based on HMDI with an NCO/OH ratio of 1.50 were better crosslinked than with those toluene diisocyanate. The thermal properties of the samples analyzed by thermogravimetric analysis showed two and three decomposition stages in aliphatic‐ and aromatic‐based RSO polyurethanes, respectively. The highest stability with initial decomposition temperature (253°C) and percentage residual at 500°C (11.4%) was achieved with an aliphatic‐based RSO polyurethane. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of low‐molecular‐weight poly(2,6‐dimethyl‐1,4‐phenylene oxide) in water

Low‐molecular‐weight poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) with unimodal polydispersity was synthesized by oxidative polymerization of 2,6‐dimethylphenol in the presence of Cu‐ethylene diamine tetraacetic acid catalyst in water. A series of low‐molecular‐weight PPO oligomers with M_n ranged from 360 to 3500 were obtained. It was found that the molecular weight and polydispersity were affected by reaction time, reaction temperature, and catalyst concentration. Based on the detector response‐elution volume curve and the molecular weight from gel permeation chromatography, a possible molecular weight growth mechanism was proposed. The structure and properties of low‐molecular‐weight PPO oligomers were characterized by atomic absorption spectroscopy, differential scanning calorimetry, Ubbelohde viscometer, and nuclear magnetic resonance spectroscopy. Compared to the commercial low‐molecular‐weight PPO, PPO oligomers synthesized in water had a much lower residual copper content. The relationships between T_g and M_n at relatively low‐molecular weight are in good agreement with the equation proposed by Fox and Loshack. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Properties of waterborne polyurethane‐fluorinated marine coatings: The effect of different types of diisocyanates and tetrafluorobutanediol chain extender content

Three series of waterborne polyurethane‐ (WBPU) fluorinated coatings were prepared with single aliphatic (4,4′‐dicyclohexylmethane diisocyanate, H₁₂MDI), aromatic (4,4′‐diphenylmethane, MDI) and a mixture of aliphatic and aromatic diisocyanates (1 : 1). Different contents of 2,2,3,3‐tetrafluoro1,4‐butanediol (TFBD) as a chain extender were used in the WBPU coatings. The fluoro‐enriched surface of the WBPU coatings was obtained with a combination of a high TFBD content (8.77 mol %) as well as the aliphatic or mixed diisocyanates. The tensile strength, Young's modulus, elongation at break (%) and adhesive strength were characterized with respect to the TFBD contents. The mechanical strength and adhesive strength increased with increasing TFBD content in the three series. In artificial salt water, the maximum adhesive strength of WBPU was observed for this coating, which was achieved by TFBD bonded H₁₂MDI of mixed diisocyanates with a higher TFBD content (8.77 mol %). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39905.     

Shape memory properties of polycaprolactone‐based polyurethanes prepared by reactive extrusion

The shape memory properties of polycaprolactone‐based polyurethanes (PCLUs) synthesized via a novel route of reactive extrusion were investigated in terms of the deformation amplitude, temperature, and rate by differential scanning calorimetry (DSC), dynamic mechanical analyzer, and polarized optical microscopy (POM). DSC analysis shows that the crystalline melting temperature and crystallinity of PCLU increased monotonically with increasing the average polymerization degree $ ( \overline {DPn}) $ of poly(ε‐caprolactone) (PCL) block. The retract force increased with increasing the temperature and reached the maximum (6–7 MPa) within 45–55°C. Furthermore, a modified model with two recovery stages was postulated to elucidate the shape memory process, which is visually presented by POM analysis. The two stages of tensile and compressive recovery are distinguished by the inflexion temperature, within 43–48°C and 64–66°C, respectively. The shape fixity is about 60–70% and can be improved to 100% by choosing proper deformation temperature. The tensile deformation recovery ratio was 80–98% due to the water absorption, whereas the compressive deformation recovery ratio was almost 100%. Besides, recovery tests show that the lowest recovery temperature ranged from 24 to 47°C was influenced by the deformation temperature, rate and the PCL block $ ( \overline {DPn}) $ . Thus, the shape memory properties can be adjusted according to different purposes. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Thermal and mechanical properties of multiple‐component aliphatic degradable polyurethanes

Macroscopic thermal and mechanical properties of complex aliphatic polycarbonate‐based polyurethane (PU) films containing degradable ester units in PU backbone were studied by a combination of several experimental techniques. Differential scanning calorimetry (DSC) revealed that the synthesized oligomeric diol (DL‐L) contributes (in addition to polycarbonate diol) to the formation of soft‐segment domains, while the hard‐segment domains are formed from 1,6‐diisocyanatohexane (HDI) and butane‐1,4‐diol (BD). Three main phase transitions were detected by DSC and by dynamic mechanical thermal analysis. Thermogravimetric analysis (TGA) of two‐component PUs showed that the PU made from DL‐L and HDI is the least thermostable product, while the PU made from polycarbonate diol and HDI is the most stable one. The differences in the thermal stability of different four‐component PUs are not important. Tensile properties very sensitively reflect the changes in composition and in microstructure of PU samples; the best tensile properties exhibits the degradable sample containing the equimolar ratio of hydroxyl groups of macrodiol, oligomeric diol DL‐L and butane‐1,4‐diol. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41872.     

Methods of long chain branching detection in PE by triple‐detector gel permeation chromatography

Long chain branching (LCB) in polyethylene is one of the key microstructures that controls processing and final properties. Gel permeation chromatography (GPC) with viscometer (IV) and/or light scattering (LS) has been intensely used to quantify LCB. The widespread method to quantify LCB from GPC with IV or LS is the method of LCB frequency (LCBf) based on the Zimm–Stockmayer (ZS) random branching model. In this work, the conventional approach was compared with the recently developed method, called gpcBR. The comparison of the sensitivity of both methods is made on highly branched polymer, that is, various grades of commercial LDPE and also on polymer with very low level of LCB, that is, a commercial HDPE with no LCB, converted into several branched test samples of gradually increasing LCB by multiple extrusion. Finally, the linkages of LCB quantities from both methods to the rheological data and processing properties are illustrated. The new gpcBR index can access lower LCB level and shows obviously better relationship with both rheological data and processing properties than LCBf from the conventional ZS model. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42222.     

Rubber‐based acrylate resins: An alternative for tire recycling and carbon neutral thermoset materials design

Rubber is a widely available potential carbon neutral resource, both as native natural rubber state and as vulcanized state in waste tires. Herein, we describe a model synthesis of acrylate telechelic natural rubber (AcTNR) oligomers and the use of such oligomers to prepare novel acrylate resins. AcTNR oligomers are synthesized according to a two steps procedure implying a controlled C = C bond's scission of high‐molecular‐weight natural rubber and a further chain ends functionalization. The molar mass of the resulting AcTNR is found to be 2300 g/mol as determined by ¹H NMR. AcTNR‐based resins are then prepared by mixing AcTNR oligomers with various reactive diluents (RD) such as styrene, 1,4‐butanediol ether, tri(propylene glycol) diacrylate, 1,6‐hexanediol diacrylate, trimethylolpropane triacrylate (AcTNR:RD weight ratio 7:3). These bio‐based resins are afterward cured in the presence of methyl ethyl ketone peroxide as initiator and cobalt octoate as accelerator at 80 °C and postcured at 120 °C. The cured resins offer a wide range of mechanical, thermal, and dynamic‐mechanical performances. This approach could be extended to rubber tire wastes. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43548.