Molecular characterization of alkyd/acrylic latexes prepared by miniemulsion polymerization

The molecular characterization of alkyd/acrylic hybrid latexes produced by miniemulsion polymerization was characterized in terms of the resin degree of grafting, acrylic degree of grafting, reacted double bonds in the alkyd, gel content, and molecular weight distribution of the sol part. A simple method based on conventional size exclusion chromatography measurements was developed to estimate the fraction of alkyd resin grafted to the acrylic polymer. The method could be applied to completely soluble hybrids and to hybrids containing gel. Also, the limits of the extraction method used in the literature to estimate the fraction of acrylic polymer grafted to the alkyd was investigated; we found that this technique only provided accurate results at high values of the acrylic degree of grafting. The combination of this information with the reacted double bonds of the alkyd (determined by iodine titration) and the molecular weight distribution of the sol polymer provided a detailed characterization of the alkyd–acrylic hybrid polymer. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Polymeric coatings based on acrylic resin latexes from miniemulsion polymerization using hydrocarbon resins as osmotic agents

Waterborne acrylic resins with a solid content higher than 40 wt % were obtained by miniemulsion polymerization of methyl methacrylate, butyl acrylate, and acrylic acid using a hydrocarbon coumarone–indene resin (HCR) as osmotic agent. HCR is a cheap polymer widely used for coatings and pressure‐sensitive adhesives. The resin leads to a higher hydrophobicity for the acrylic latex film and acts as osmotic agent in miniemulsion polymerization preventing Ostwald ripening, leading to latexes with particle sizes, size distributions, and stability comparable to those obtained using n‐hexadecane as osmotic agent. However, the monomer conversion and molecular weight were lower, indicating the occurrence of a chain‐transfer reaction. Atomic force microscopy analysis demonstrated that a smooth film surface with phase‐separated morphology was formed when using HCR. Faster film hardness development was achieved with HCR comparing with hexadecane. Compared with market standard in a paint formulation, a similar performance was achieved. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40569.     

Fluorine containing self‐crosslinking acrylic latexes with reduced flammability and their application as polymer binders for heterogeneous cation‐exchange membranes

In this study, self‐crosslinking core–shell latexes comprising copolymerized perfluorethyl groups and a novel flame retardant based on phosphazene derivative were prepared by the semi‐continuous non‐seeded emulsion polymerization of 2,2,2‐trifluorethyl methacrylate, methyl methacrylate, butyl acrylate, methacrylic acid, and hexaallylamino‐cyclo‐triphosphazene as main monomers. For interfacial crosslinking, diacetone acrylamide was copolymerized into the shell layer of latex particles to provide sites for subsequent reaction with adipic acid dihydrazide. The heterogeneous cation‐exchange membranes were obtained by dispersing commercial strong acid cation‐exchange resin powder in the latex binder and casting the mixture followed by keto‐hydrazide crosslinking reaction. It was found that the increased concentration of fluorine atoms and phosphazene units in the macromolecular structure of interfacially crosslinked emulsion polymers resulted in a significant enhancement of their flame resistance and shape stability in aqueous environment. Moreover, the easily prepared heterogeneous cation‐exchange membranes based on latexes with higher amounts of fluorine and phosphazene units were shown to exhibit satisfactory physicochemical and electrochemical properties. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45467.     

Emulsifier‐free cationic latexes based on vinylbenzyl chloride and 2‐(dimethylamino)ethyl methacrylate with adjusted hydrophilic–hydrophobic properties

Functional emulsifier‐free cationic latexes based on styrenic monomer vinylbenzyl chloride (VBC) and acrylic monomer 2‐(dimethylamino)ethyl methacrylate (DMA) were successfully prepared with dual quaternary ammonium ions (36–63 mol %) on both monomer moieties in two‐stages. First, [2‐(methacryloyloxy)ethyl]dimethylhexadecylammonium bromide monomer (DMA(C₁₆)), prepared via quaternization of DMA with 1‐bromohexadecane, was utilized as a comonomer (5–20%) as well as a surfactant in the emulsion polymerization of VBC. Next, the quaternization of chloromethyl groups in the VBC moiety in latex particles with trimethylamine and N,N‐dimethylhexadecylamine created a second type of quaternized sites on the latex particles. The percentages of the quaternary ammonium ions of the first‐stage latexes (P[VBC‐DMA(C₁₆‐x)]) and the second‐stage latexes (P[VBC(R)‐DMA(C₁₆‐x)]) were determined using bromide and chloride ion‐selective electrodes. The particles were characterized with a scanning electron microscope, Zetasizer, measuring water contact angles of their pellets. The polymer structure and the alkyl group length in their quaternary ammonium ions played an important role on the sizes, zeta potentials and hydrophilic–hydrophobic balances of the latexes. The water contact angles of the pellets of the latex particles varied from 50.3 to 109.6° depending on both the polymer structure and the alkyl group length. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42775.     

Ferroelectric nanodot formation from spin‐coated poly(vinylidene fluoride‐co‐trifluoroethylene) films and their application to organic solar cells

We demonstrated a facile route to the preparation of self‐assembled poly(vinylidene fluoride‐co‐trifluoroethylene) [P(VDF‐TrFE)] nanodots from spin‐coated thin films. We found that the initial film thickness would play an important role in the formation of such P(VDF‐TrFE) nanodots. Interestingly, the electric dipoles of such nanodots were self‐aligned toward the bottom electrode and their ferroelectric properties were determined by using piezoresponse force microscopy. In addition, the self‐polarized ferroelectric nanostructures were introduced to small molecular organic photovoltaic devices and allowed for enhancing the short circuit current density (J_sc) from 9.4 mA/cm² to 10.2 mA/cm² and the power conversion efficiency from 2.37% to 2.65%. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41230.     

Poly(methyl methacrylate) copolymer nanocapsules containing phase‐change material (n‐dodecanol) prepared via miniemulsion polymerization

Poly(methyl methacrylate) copolymer nanocapsules containing the phase‐change material n‐dodecanol, which could be used for energy storage, were prepared with different comonomers via miniemulsion polymerization. The thermal properties, morphology, and composition of nanocapsules were characterized with differential scanning calorimetry, thermogravimetric analysis, transmission electron microscopy, and Fourier transform infrared spectroscopy. The results show that the thermal properties and morphology of the nanocapsules were influenced greatly by the type and amount of comonomers. Under the same dosage of 4 wt %, the nanocapsules prepared with the comonomer acrylamine and which had a moderate hydrophilicity showed the highest phase‐change latent heat of 109.3 J/g; the acrylamine that had a moderate hydrophilicity and the highest encapsulation efficiency of 91.3%. The size of the nanocapsules ranged from 50 to 100 nm with a uniform spherical shape and apparent core–shell structure. We also found that when the amount of the soft comonomer butyl acrylate was increased, the phase‐change latent heat of the nanocapsules first decreased slightly, then increased to the maximum value with deformed spherical and conglutinated morphology, and finally decreased continuously. The thermal stability of the nanocapsules became weaker with higher contents of core material. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42334.     

Synthesis of fluoroalkyl‐modified polyester and its application in improving the hydrophobicity and oleophobicity of cured polyester coatings

The fluoroalkyl‐modified polyester (PE‐F_n) was synthesized by the reaction of polyester resin (PE) and fluorinated isocyanate, and the structure of the synthesized product was characterized by proton nuclear magnetic resonance (¹H‐NMR) and fluorine nuclear magnetic resonance (¹⁹F‐NMR). The water and oil wettability of the cured PE coatings with PE‐F_n as additives was investigated by contact angle meter. The results showed that the introduction of an extremely low concentration of PE‐F_n into PE led to the increase in contact angle of water and diiodomethane on cured PE coatings, and the decrease in the surface free energy. The X‐ray photoelectron spectroscopic (XPS) analysis showed that the F/C molar ratio in the outer few nanometers was significantly higher than that in the bulk, indicating that the fluoroalkyl groups in PE‐F_n had enriched on the coating surface. It was also found that longer fluoroalkyl groups and fluoroalkyl groups with ? CF₃ at its end had the higher tendency to aggregate on the coating surface. The topological structures of the cured coatings were recorded by an atomic force microscope under tapping mode and the results revealed that there was a strong surface segregation of fluorinated species. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39812.     

Two‐stage stabilizer addition protocol as a means to reduce the size and improve the uniformity of polymer beads in suspension polymerization

A two‐stage stabilizer addition protocol is suggested for reducing the size and improving the uniformity of polymer beads resulting from conventional suspension polymerization. The stabilizer load was divided into an initial charge and a secondary addition. The use of a low concentration of stabilizer in the initial charge served to assist drop rupture while avoiding significant reduction in drop size and production of too many satellite droplets. The secondary addition time of stabilizer occurred just before the onset of the growth stage when drops were vulnerable to coalescence but robust against break up due to their high viscosity. The secondary addition of stabilizer served to provide stability to monomer drops during the growth stage and as a result the drops underwent limited coalescence. This resulted in the formation of smaller and more uniform polymer beads in comparison to beads obtained by conventional suspension polymerization at the same overall concentration of stabilizer. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45671.     

The effect of nonionic monomer HAM on properties of cationic surfactant‐free acrylic/alkyd hybrid emulsion

A series of cationic acrylic/alkyd resin (CPAAR) hybrid emulsions was successfully prepared through surfactant‐free emulsion polymerization, using methacryloxyethyltrimethyl ammonium chloride, methyl methacrylate, butyl acrylate and alkyd resin as reaction monomers. And nonionic N‐hydroxymethyl acrylamide (HAM) of different content was simultaneously incorporated into the CPAAR backbone. The structure of CPAAR copolymer was characterized by Fourier transform infared spectrometer, and then the effect of HAM content on properties of CPAAR emulsions was studied by particle size analyzer, transmission electron microscopy and rheometer. In addition, thermal properties, water absorption and contact angle of CPAAR latex films were also investigated. The results showed that the CPAAR emulsions prepared with 4.9 wt % HAM displayed smallest average particle size of 92.2 nm. As HAM content increased from 0 to 19.6 wt %, the initial viscosity of the emulsions increased from 22.48 to 53 mPa.s. At the same time, the emulsions transferred from Newtonian fluid to pseudoplastic fluid, and a transition from viscous liquid to elastic liquid was also detected. Meanwhile, the degradation temperature at 5% weight loss increased by 30.59°C. In addition, with increasing HAM content from 0 to 4.9 wt %, the water absorption and surface free energy of films increased by 4.42% and 5.02 mJ m^?2, respectively. However, the water absorption and surface free energy kept almost invariable with further increase in HAM content. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41406.     

Wear‐resistant cotton fabrics modified by PU coatings prepared via mist polymerization

Cotton fabric was successfully modified using a simple mist polymerization with polyurethane (PU) prepolymer and ethylene glycol as the monomers. Scanning electron microscope showed the presence of a very thin polymer coating on the cotton fiber surface. Martindale abrasion tests revealed that the thin PU coating imparted to the cotton fabric a doubled wearing durability compared with the original fabric. Additional experiments demonstrated that the mist polymerization has little impact on the desired cotton properties such as water absorptivity, vapor transmissibility, mechanical property, and flexibility. Considering the excellent balance between the enhanced abrasion resistance and the cotton natures, this surface modification methodology has potential to fabricate wearing durable textiles. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43024.     

微小乳液聚合制备丙烯酸酯杂化聚氨酯分散液

微小乳液聚合工艺技术在25~30年前即已问世,但用于丙烯酸酯杂化聚氨酯分散液的制备仅有10年历史。用该工艺技术可有效制得稳定的纳米级丙烯酸酯杂化聚氨酯分散液,其性能独特。本文阐述了微小乳液聚合工艺的原理、影响因素、存在问题和解决措施,并以实例说明之。     

Preparation of hybrid composite microspheres containing nanosilicon via microsuspension polymerization

Hybrid composite microspheres with nano‐Si as the core and poly(styrene‐co‐acrylonitrile) as a shell are successfully prepared by a two‐step polymerization technique, which includes dispersion polymerization of styrene and 3‐methacryloxypropyl trimethoxysilane in ethanol for surface modification of nano‐Si followed by microsuspension polymerization of styrene and acrylonitrile in an aqueous phase for encapsulating nano‐Si into an SAN copolymer matrix. The structure and surface properties of modified nano‐Si are investigated by Fourier transform infrared spectroscopy (FTIR) and contact angle. The hybrid composite microspheres are systematically characterized by energy dispersive spectroscopy, thermogravimetric analysis, and transmission electron microscopy (TEM). According to the FTIR spectra and the contact angle experiments, it was determined that a hydrophobic polymer layer was formed on the surface of nano‐Si. TEM showed that nano‐Si was homogeneously dispersed in SAN particles when the loading capacity of nano‐Si in the hybrid composite microspheres was less than 20 wt %. Moreover, scanning electron microscopy and X‐ray photoelectron spectroscopy revealed that there were large amounts of nano‐Si absorbed on the surface of the hybrid composite microspheres, and the mean particle size became much larger when the loading amounts of nano‐Si reached 25 wt %. From this, it can be inferred that nano‐Si overflows from the inner core to the outside surface in the emulsification process and acts as an inorganic dispersant. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43101.     

Waterborne oil‐modified polyurethane coatings via hybrid miniemulsion polymerization

As part of a wider effort to develop a new class of waterborne coatings, hybrid miniemulsion polymerization was carried out with acrylic monomers (methyl methacrylate, butyl acrylate, and acrylic acid) in the presence of oil‐modified polyurethane resin. Latexes with different ratios of resin to acrylic monomers were synthesized. The monomer emulsions prepared for hybrid miniemulsion polymerization showed excellent shelf‐life stability (>5 months) and the polymerization was run free of coagulation. Solvent extraction indicated that the grafting efficiency of polyacrylics was greater than 29% for all the samples produced. A ¹³C solution NMR spectrum showed that a substantial fraction of the original carbon double bonds (>61%) in oil‐modified polyurethane remained after polymerization for film curing. Films obtained from the latexes presented good adhesion properties and fair hardness properties. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 105–114, 2000     

Influence of compositions and polymerization processes on morphologies,molar mass distributions,and phase structures of n‐Butyl acrylate–methyl methacrylate copolymers

The target of the research is to examine influence of a polymerization process and monomer ratio on structures and compositions of phases in an emulsion copolymerization of n‐butyl acrylate (BA) and methyl methacrylate (MMA). Emulsion copolymerizations are performed using three different BA/MMA weight ratios (60%/40%, 50%/50%, and 40%/60%) and two different processes, statistical batch and seeded emulsion polymerizations. Phase structures, monomer compositions, and morphological stabilities of copolymers are investigated by differential scanning calorimetry, ¹H‐NMR, and scanning electron microscopy. Gel permeation chromatography is used to follow the changes in the molar mass distribution during syntheses. The gel content and backbiting level of end products are measured by extraction and ¹³C‐NMR, respectively. Copolymerizations give products with a bimodal molar mass distribution and three or two separate phases having different BA/MMA compositions. The morphological stability of particles decreases with the increasing BA fraction in the feed. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41467.     

Synthesis and characterization of fluorinated organic–inorganic hybrid coatings on tinplate

Fluorinated organic–inorganic hybrid coatings with interpenetrating network for corrosion protection of tinplate were prepared by hydrolysis and condensation reaction of tetraethoxysilane and 3‐methacryloxypropyltrimethoxysilane, followed by radical polymerization of trimethylolpropane triacrylate dodecafluoroheptyl methacrylate. The highly crosslinked organic network was developed and attached to the inorganic moieties through covalent Si–C bonds. The hybrid coatings were characterized by scanning electron microscope, water contact angle, Fourier transformed infrared spectroscopy, and thermogravimetric analysis. Their anticorrosion performances were evaluated by potentiodynamic polarization, electrochemical impedance spectroscopy and salt spray test. The results indicated that the fluorinated hybrid coatings exhibited excellent anticorrosion ability by forming a hydrophobic physical barrier between tinplate substrate and its external environment. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42428.     

Modification of jute fabric via laccase/t‐BHP‐mediated graft polymerization with acrylamide

Enzymatic processes provide new perspectives for the modification of lignocellulose materials. Lignin is an excellent substrate for laccase, and the modification of lignin‐rich jute fabric via graft polymerization with acrylamide (AAm) mediated by laccase and tert‐butyl hydroperoxide (t‐BHP) was investigated in this study. The products obtained were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The grafting rate was determined in terms of elemental analysis. The hydrophilicity and thermal and dyeing properties of the modified jute fabric were studied. The results supported the conclusion that the polyacrylamide was grafted on the lignin of the jute fiber by laccase in coordination with t‐BHP, representing a grafting rate of 2.87%. The hydrophilicity, thermostability, dye uptake, and dyeing depth of the jute fiber were increased after the enzymatic graft modification with AAm. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40387.     

Preparation and characterization of a polydimethylsiloxane‐modified,epoxy‐resin‐based polyol dispersion and its crosslinked films

Waterborne polydimethylsiloxane‐modified epoxy‐resin‐based polyol dispersions were synthesized by the reaction of 2,4‐toluene diisocyanate with 2,2‐bis(hydroxymethyl) propionic acid, hydroxypropyl‐terminated polydimethylsiloxane (HTPDMS), and bisphenol A epoxy resin based polyol. These HTPDMS‐modified polyol dispersions exhibited a small particle size and an excellent dispersion stability. Two‐component waterborne polyurethane (2K‐WPU) was prepared from the HTPDMS‐modified polyol dispersion and a hydrophilic‐modified polyisocyanate. The structure of the HTPDMS‐modified polyol and its crosslinked 2K‐WPU films (SEFs) were characterized with Fourier transform infrared and NMR spectroscopies. The effects of the HTPDMS content on the mechanical and thermal properties of the resulting SEFs were investigated. The results show that the thermal stability of the crosslinked SEFs was enhanced with increasing HTPDMS content, whereas the modulus, tensile strength, and pencil hardness values of the films decreased with increasing HTPDMS content. Siloxane segments migrated onto the surface during the film‐formation process. The contact angle of the films increased from 71 to 96 °, and the water absorption ratio of the films decreased from 6.6 to 5.0% when the HTPDMS content in the films increased from 0 to 10%. These results indicate that the water resistance of the films was enhanced by the introduction of HTPDMS into the 2K‐WPU networks. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44342.     

The colloidal properties of alkaline‐soluble waterborne polymers

Waterborne polymer dispersions are widely used in coatings and graphic arts markets as environmentally friendly and more sustainable alternatives to solvent borne binders. Traditionally, waterborne (meth)acrylic dispersions are prepared by emulsion polymerization using low molar mass surfactants as a key ingredient to control particle size. However, these surfactants can have a negative influence on the performance of coatings such as reduced water resistance and adhesion. To mitigate the negative effects of surfactants, polymer latexes have been developed that employ alkaline‐soluble polymers as the sole stabilizer for a subsequent emulsion polymerization step. In this way surfactant‐free polymer dispersions are obtained. Despite the high commercial impact and relevance of this technology, fundamental studies regarding the physicochemical properties of the alkaline‐soluble polymers are lacking. In this article, the synthesis and colloidal properties of alkaline‐soluble waterborne methacrylic copolymers are reported. The dissolution behavior and colloidal properties of these alkaline‐soluble polymers were studied as function of molar mass, acid content, and pH. The dissolving polymer particles were characterized using static and dynamic light scattering, static and dynamic surface tension measurements, and cryogenic‐transmission electron microscopy analysis. It is concluded that the dissolution mechanism of alkaline‐soluble polymers follows a gradual process. As the pH increases deprotonation of the carboxylic acid groups swells the particle enhancing the further swelling with water. At a certain amount of base, the particles disintegrate into small polymer aggregates while the most water‐soluble polymer chains are dissolved in the water phase. An important learning is that part of the alkaline‐soluble polymer resides in very small particles (<5 nm). The formation of these polymer particles below 5 nm was not reported previously and offers a new insight into the dissolution mechanism of alkaline soluble polymers. The most important parameter steering this process is the acid value of the polymer, while the molar mass plays a modest role. The understanding gained in this study can be used to further advance alkaline‐soluble polymers as stabilizer in surfactant‐free emulsion polymerization technology, improving the performance of a wide range of industrially relevant coatings. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46168.     

Preparation of raspberry‐shaped styrene‐butadiene‐methyl acrylate‐acrylic acid latex particles by emulsion polymerization followed by alkali/heating method

Monodispersed raspberry‐shaped polystyrene‐butadiene‐methyl acrylate‐acrylic acid particles were made by semi‐batch emulsion polymerization followed by alkali and heat treatment. The particle sizes and size distributions were studied by hydrodynamic chromatography and transmission electronic microscopy. The morphology of the particles was observed by SEM, cryo‐SEM, and TEM. Treatment temperature was found to have a significant impact on the particle size and morphology of the treated latexes. Higher temperatures lead to larger particle sizes and more discernible raspberry domains with sizes around 50 nm on the particle surfaces. Higher levels of alkali did not significantly change the particle size but did increase the total titratable acid amount, presumably due to the hydrolysis of methyl acrylate during the treatment. GPC results showed that higher amount of oligomers or polymers are produced in the serum for the heat‐treated latexes. Divinylbenzene crosslinking agent at the levels of 0.05–3% limited the particle expansion and decreased the serum acid. A possible mechanism of raspberry particle formations was proposed, which involves migration of hydrophilic and hydrophobic species during the heat treatment. Lastly, potential applications for raspberry particles in paper coating were explored. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Unique alkyl ketene dimer Pickering‐based dispersions: Preparation and application to paper sizing

Herein, particle‐stabilized alkyl ketene dimer (AKD) dispersions were prepared using dodecyl trimethyl ammonium chloride (DTAC)‐modified laponite as the stabilizer, and sodium alginate (SA) as the protective colloid. The modification of laponite particles with DTAC, which was characterized by transmission electron microscopy, infrared spectroscopy, and X‐ray diffraction technique, moderately decreases the negative zeta potential and causes the dehydration of laponite particles. Consequently, the modification of laponite promotes the absorption of laponite particles on AKD droplets/spherical particle surfaces, leading to formation of AKD dispersions with reduced particle size and enhanced uniformity when DTAC‐to‐laponite mass ratio is <1%. Meanwhile, SA significantly increases the stability of the AKD dispersions and provides stable AKD dispersions with smaller particles when SA‐to‐AKD mass ratio is <0.08%. By means of confocal laser scanning microscopy, scanning electron microscope imaging and energy dispersive spectroscopy (EDS)/EDS mapping, the function of DTAC‐modified laponite particles in stabilization of AKD dispersions was found to include both formation of a particle barrier around AKD particles and an increase in the moving resistance of AKD particles by laponite particles with SA. AKD dispersions at a DTAC‐to‐laponite mass ratio 1.0% and SA‐to‐AKD mass ratio 0.054% provide the smallest droplet size and best sizing performance. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45730.