Coating water-swellable polymer latexes by interfacial polymerization

Two techniques of coating water-swellable polymer latexes (hydrogels) with an inorganic or organic layer were developed, based on interfacial polymerization. The hydrogel latexes were prepared by inverse suspension polymerization. The first kind of interfacial polymerization is hydrolysis and polycondensation of tetraethyl orthosilicate (TEOS) or 3-(trimethoxysilyl) propylmethacrylate (TMS-PMA) on the surface of hydrogel latexes. The hydrochloric acid, which is the catalyst for this reaction, was previously loaded into the hydrogel latexes. The HCL-containing hydrogel latexes were then suspended in an organic solution of TEOS or TMS-PMA. The hydrolysis and condensation occur only at the surface of each hydrogel particle and the generated SiO₂ or SiO(PMA) network covers the hydrogel latexes. The second interfacial polymerization is polymerization of methylenedi-p-phenyl diisocyanate (MDI) and triethylene glycol (TEG) on the surface of hydrogel latexes. TEG was deposited on the hydrogel by suspending the hydrogel powder in a tetrahydrofuran (THF) solution of TEG and evaporating the THF. The TEG-deposited hydrogel powder was then suspended in an organic solution containing both MDI and the catalyst dibutyltin dilaurate (DBTL). The MDI and DBTL molecules react with the TEG molecules only at the surface of the hydrogel particles, and the polyurethane P(MDI-TEG) thus formed wraps the particles. Based on these two coating procedures, three kinds of materials were obtained: SiO₂ coated hydrogels, SiO-(PMA) coated hydrogels and P(MDI-TEG) coated hydrogels. Soft polyether brushes were grafted to the SiO-(PAM) coated latexes. The P(MDI-TEG) coated hydrogels were used as reservoirs for β-hydroethyltheophylline (β-HETP), and the release of the latter molecules from the coated hydrogels was investigated. © 1995 John Wiley & Sons, Inc.     

微乳中界面聚合法制备包载胰岛素纳米胶囊

通过界面聚合法,以嵌段共聚物表面活性剂作为乳化剂得到结构紧密的微乳液,在该微乳液中制备聚氰基丙烯酸乙酯(PECA)纳米胶囊,产物粒径较小(约100 nm),与作为模板的微乳液液滴大小相对应.微乳组成对纳米胶囊粒径影响较大.微乳聚合所得聚氰基丙烯酸乙酯纳米胶囊对胰岛素的包裹率较大,最大超过90%.同时考察了胰岛素从纳米胶囊中的释放行为.     

Polyaniline nanofibers obtained by interfacial polymerization for high-rate supercapacitors

Polyaniline (PANI) nanofibers were fabricated by interfacial polymerization in the presence of para-phenylenediamine (PPD). The additives cannot only have a profound impact on the polymers morphology, but can also improve their specific energy and specific capacitances. It was found that PANI nanofibers prepared in the presence of PPD were longer and less entangled than those in the absence of PPD due to a much faster polymerization rate in initial stage. A specific capacitance value of 548 F g⁻¹, a specific power value of 127 W kg⁻¹ and a specific energy value of 36 Wh kg⁻¹ were obtained in polyaniline nanofibers prepared in the present of PPD at a constant discharge current density of 0.18 A g⁻¹.     

可逆失活自由基界面聚合

界面聚合通常指限定在液-液或液-固界面上进行的聚合反应,散见于少数高活性的缩聚反应体系。20世纪90年代,以RAFT聚合、ATRP等为代表的可逆失活自由基聚合（reversible deactivation radical polymerization,RDRP）因其兼具传统自由基聚合和活性阴离子聚合的优点,广泛用于聚合物链结构的可控制备。另一方面,RDRP已被用于构建更为普适的界面聚合反应,基于RDRP的界面聚合已发展成为一种可控制备具有精准纳米结构的功能性聚合物产品的新方法。本文以RAFT液-液界面聚合为主,阐述了RAFT法和ATRP法在液-液界面、液-固界面进行“活性”聚合的反应机理,总结了该领域的研究进展。在此基础上,重点介绍“活性”界面聚合在构建纳米（中空）胶囊、纳米界面工程与纳米分散以及纳米聚合物刷表面等方面的潜在应用前景。     

Photochromic performance optimization of polyurethane microcapsules by interfacial polymerization method

Spiropyran photochromic materials have been widely studied in military camouflage, optical data storage, information encryption, and fashion ornaments. The non-photochromism and low endurance of solid spiropyran make the challenges of their application. Photochromic microcapsules with a butyl acetate solution of spiropyran as core and polyurethane as shell are synthesized via interfacial polymerization. The optimized polyurethane photochromic microcapsules are prepared with a Tween 20 concentration of 4 wt%, core–shell ratio of 16:5, and spiropyran concentration of 0.40 wt%. Polyurethane photochromic microcapsules with a mean particle diameter of 0.33 μm are obtained. The morphology shows smooth spheres, and the core–shell structure is observed. Butyl acetate in the microcapsule core does not evaporate at a temperature lower than 218.01°C as the microcapsule shell insulates heat. The polyurethane photochromic microcapsules are mixed with adhesive, thickener, and water into a paste and screen-printed on cotton fabric. The printed fabric shows the ΔE of 17.56, 11.93, and 6.96 after 80s irradiation with the xenon lamp intensity of 102, 68, and 34 mW cm⁻². The light stability of the photochromic fabric is excellent as ΔE decreases about 8.28% after 20 cycles of UV-Vis irradiation.     

Polypyrrole composite membrane with high permeability prepared by interfacial polymerization

Novel polypyrrole (PPy)/polydimethylsiloxane (PDMS) composite membrane was prepared by interfacial polymerization to make a very effective gas separation membrane. We found that Polymerized PPy films as thin as ～200 nm could be chemically synthesized as freestanding membranes by using the interfacial polymerization technique. Additionally, we show that difference morphology of PPys films was obtained by controlling polymerization rate and more dense films were formed at low polymerization rate. Wide X-ray diffraction study showed the d spacing value of the PPy film decreased from 4.89 å to 3.67 å by the rate of polymerization decreases. According to d spacing value decrease, selectivity of a PPy composite membrane was increased dramatically and permeability was reduced gradually. This high selectivity was derived from d spacing closed to the kinetic diameter of nitrogen. These results indicated that the permeability is controlled by the diffusion coefficient, reflecting the packed structure of the PPy film. The highest selectivity value of composite membrane that was prepared by interfacial polymerization was O₂/N₂=17.2 and permeability for O₂ was 40.2 barrer.     

Current trends in interfacial polymerization chemistry

Interfacial polymerization is an enabling technique for the large-scale production of ultrathin layers, hollow nanospheres and nanofibers. The availability of a wide range of suitable monomer reactants allows for the synthesis of an impressive collection of polymers, including polyamides, polyurethanes, polyureas, polyanilines, polyimides, and polycarbonates. In addition, the technique has been used to prepare defect-free, ultrathin films of metal organic frameworks, organic-inorganic hybrids, and bio-hybrids. This review provides an overview of the chemistry that is used in interfacial polymerization, discusses the (dis)advantages of derived material types, and assesses the future prospects for synthesis of ultrathin functional materials via interfacial polymerization.     

ε-Caprolactam polymerization in presence of polyhedral oligomeric silsesquioxanes (POSS)

Polyhedral oligomeric silsesquioxanes (POSS) have been covalently linked to polyamide 6 (PA6) chains with the aim of synthesizing hybrid organic/inorganic polymer materials. The synthesis has been achieved by in situ polymerization of ε-caprolactam (CL) in presence of increasing amounts of POSS molecules, using two polymerization mechanisms (hydrolytic and anionic). The latter method has been carried out by three different approaches, in order to get PA6 samples characterized by various morphologies and content of structural defects: (i) quasi-adiabatic bulk polymerization; (ii) isothermal bulk polymerization; (iii) quasi-isothermal suspension polymerization. The products obtained have been characterized in term of structure, morphology, thermal properties and molecular mass.     

Nanofiltration membranes prepared by interfacial polymerization on thin-film nanofibrous composite scaffold

Nanofiltration (NF) membranes, consisting of a composite barrier layer prepared by interfacial polymerization of polyamide around the ultra-fine cellulose nanofibers (CN) layer in a thin-film nanofibrous composite (TFNC) scaffold, were demonstrated. Two interfacial polymerization pathways (termed IP and IP-R), regarding the arrangement of the aqueous and organic phases, were investigated. It was found that interfacial polymerization with the aqueous phase above the organic phase (IP-R) yielded better filtration performance, i.e., IP-R based membranes exhibited a higher MgCl₂ rejection than IP based membranes. Transmission electron microscopy (TEM) observation indicated that the denser part of the barrier layer was on the CN layer surface of IP-R based membranes, whereas this portion was deeply immersed in the CN layer of IP based membranes. To investigate the structure and property relationship of the composite barrier layer, both IP and IP-R based membranes were treated with 1% trimesoyl chloride (TMC) in hexane. After treatment, the rejection of NaCl was found to increase from 74% to 91% for IP-R based membranes, while remained unchanged (∼75%) for IP based membranes. This behavior can be explained by the decrease in pore size due to the cross-linking of TMC and secondary amino groups in the barrier layer of IP-R based membranes, while the permeability in IP based membranes was probably mainly controlled by the water passage through channels formed at the interface between CN and polymer matrix in the barrier layer of IP based membranes, which is not dependent of the cross-linking reaction.     

Fabrication of DBSA‐doped polyaniline nanorods by interfacial polymerization

An interfacial polymerization was used to fabricate dodecybenzenesulfonic acid (DBSA)‐doped polyaniline (DBSA‐PANI) nanorods with diameter range from 40 nm to 1 μm. The molar ratio of aniline to ammonium peroxydisulfate (APS), the concentrations of DBSA and reaction temperature had an effect on the morphology and size of products. It was found that lower concentration of DBSA and lower temperature will be helpful to the formation of rod‐like PANI nanostructures with a relative small diameter. UV–vis and FTIR measurements were used to characterize the chemical structure of the obtained samples. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation and electrochemical performances of porous polypyrrole film by interfacial polymerization

In this study, porous polypyrrole (PPy) film was synthesized by facile interfacial polymerization using ionic liquid as oxidant. The morphology of PPys changed from dense microspherical/nanospherical agglomerated structure to porous structure with the increasing concentration of the oxidant. The magnetic ionic liquid, 1‐butyl‐3‐methylimidazolium tetrachloroferrate (Bmim[FeCl₄]), played a major role of oxidant when the concentration was lower than 0.075M. As the concentration increased to 0.075M, the π–π interactions between pyrrole cations and iminazole ring of Bmim[FeCl₄], as evidenced by Fourier transform infrared spectrometer results, may affect the packing of PPy chains and subsequently cause the formation of porous structure of PPys. Electrochemical performances showed that PPy with porous structure displayed the highest specific capacitance of 170 F/g at a current density of 2 A/g in 1M H₂SO₄ solution and a good capacitive behavior, which has potential application as supercapacitor materials. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Ordered mesoporous silica prepared by quiescent interfacial growth method - effects of reaction chemistry

Acidic interfacial growth can provide a number of industrially important mesoporous silica morphologies including fibers, spheres, and other rich shapes. Studying the reaction chemistry under quiescent (no mixing) conditions is important for understanding and for the production of the desired shapes. The focus of this work is to understand the effect of a number of previously untested conditions: acid type (HCl, HNO₃, and H₂SO₄), acid content, silica precursor type (TBOS and TEOS), and surfactant type (CTAB, Tween 20, and Tween 80) on the shape and structure of products formed under quiescent two-phase interfacial configuration. Results show that the quiescent growth is typically slow due to the absence of mixing. The whole process of product formation and pore structuring becomes limited by the slow interfacial diffusion of silica source. TBOS-CTAB-HCl was the typical combination to produce fibers with high order in the interfacial region. The use of other acids (HNO₃ and H₂SO₄), a less hydrophobic silica source (TEOS), and/or a neutral surfactant (Tweens) facilitate diffusion and homogenous supply of silica source into the bulk phase and give spheres and gyroids with low mesoporous order. The results suggest two distinct regions for silica growth (interfacial region and bulk region) in which the rate of solvent evaporation and local concentration affect the speed and dimension of growth. A combined mechanism for the interfacial bulk growth of mesoporous silica under quiescent conditions is proposed.     

Nylon 610 and carbon nanotube composite by in situ interfacial polymerization

Poly(hexamethylenesebacamide) (nylon 610) nanocomposites containing well dispersed multi-walled carbon nanotubes (MWNTs) were successfully produced via the in situ interfacial polymerization of two liquid phases, one containing hexamethylenediamine in the presence of MWNTs and the other containing sebacoyl chloride. The processing consisted of dispersing acid-treated MWNTs in an aqueous phase containing a Triton X-100 surfactant. Scanning and transmittance electron microscopies showed that the individual MWNTs were uniformly dispersed in the nylon 610 matrix. Tensile tests of the composite sheet showed a 170% increase in the Young's modulus with slight increases in the tensile strength and the elongation at break (about 40 and 25%, respectively). This suggests an interaction between the acid-treated MWNTs and nylon 610. The thermal stability of the composite was also enhanced by the incorporation of MWNT into nylon 610 matrix.     

Textile‐surface interfacial asymmetric polymerization

This research demonstrated that polymerization of aniline on cellulose produces chiroptically active composites. Polymerization of aniline in the presence of cotton fibers consisting of chiral cellulose are performed to prepare a polyaniline (PANI)/cotton composite. The polymerization is conducted at the cotton interface. The resultant PANI/cotton composite shows chiroptical activity elucidated with diffuse reflectance circular dichroism. In this reaction, textile‐surface interfacial asymmetric polymerization is performed with imprinting of chiral structure from the cotton as a natural chiroptically active polymer to the PANI. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41118.     

Dielectric and optical properties of nitrogen-incorporated polyethylene films fabricated by plasma polymerization

The dielectric and optical properties of nitrogen-incorporated polyethylene films fabricated by radio-frequency glow discharge in ethylene-nitrogen (C₂H₄ ? N₂) gas mixtures have been measured for various nitrogen concentrations. The results show that the plasma-polymerized films have distinct properties from the ones based on conventional chemical polymerization. The incorporation of nitrogen in polyethylene results in an increase in breakdown strength, dissipation factor, and dielectric constant at frequencies below the optical frequency range, and in a decrease in dark conductivity, and in photoconductivity and extinction coefficient in the optical frequency range. However, the incorporation of nitrogen does not cause significant change in refractive index. The effects of the incorporation of nitrogen in polyethylene are attributed to the shallow acceptor-like traps introduced by incorporated nitrogen.     

Self‐assembled polypyrrole film by interfacial polymerization for supercapacitor applications

A facile interfacial synthesis strategy is proposed to synthesize self‐assembled polypyrrole (PPy) free‐standing films for electrochemical capacitors with the assistance of surfactants. The chemical structure of the obtained samples is characterized by Fourier transform infrared. The morphologies of the samples are studied by scanning electron microscope. The results show that the prepared PPy films own highly porous structures using Tween80 as a surfactant, while the synthesized PPy films have vesicular structures by adding Span80 as a surfactant. Furthermore, lowering polymerization temperature makes PPy films have smaller and more pores or vesicles. The PPy films prepared at 0°C with Tween80 as a surfactant possess a high specific capacitance of 261 F g^?1 at 25 mV s^?1 as well as retain 75% of the initial specific capacitance value after 1000 cycles. The good electrochemical properties can be attributed to the highly porous structural advantage of the PPy films caused by Tween80. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41615.     

Preparation and characterization of novel polyamide paraffin MEPCM by interfacial polymerization technique

A novel polyamide‐paraffin microencapsulated phase change material (MEPCM) was prepared by interfacial polymerization technique using 1,3,5‐benzenetricarbonyl chloride (TMC) and ethylenediamine as monomers and 30# paraffin as core material. Morphology, chemical composition, thermal properties of the MEPCM were studied by scanning electron micrograph, FT‐IR spectrum, differential scanning calorimeter analysis and thermogravimetric analysis. The solvent resistances of the MEPCM were also studied by observing the morphology changes of the MEPCM under optical microscope. Results indicate that the MEPCMs prepared under optimal conditions have spherical shape with average diameter of 6.4 µm, and the polyamide shell has successfully packaged the paraffin core. The MEPCM has a high efficiency in storing and releasing heat. The latent heat is 121.7 J/g and the microencapsulation ratio is 87%, 5% weight loss temperature is 260°C. The MEPCM is stable in H₂SO₄ solution (ω = 0.98), NaOH solution (ω = 0.40), ethanol, acetone, ether, dimethylformamide while can be destroyed by ZnCl₂ solution (ω = 0.60). © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci, 2013     

Network polyimide membranes prepared by interfacial polymerization for hot H2 purification

Novel polymeric membranes are to be developed for hot H₂/CO₂ separation. In this work, network polyimide (PI) membranes are prepared via a simple interfacial polymerization method using low-cost melamine and pyromellitic dianhydride monomers. The membrane performance surpasses the upper bound of H₂/CO₂ separation. Moreover, the membranes exhibit a H₂/CO₂ separation factor of 18.7 at 623 K and a robust performance after treatment with steam and H₂S.     

界面聚合中空纤维正渗透膜的制备和表征

以聚砜为原料,通过浸没沉淀法制备中空纤维基膜,然后采用界面聚合法制备出中空纤维正渗透膜。考察了制膜参数、基膜结构和FO性能三者之间的关系。结果表明基膜的厚度为影响FO性能的主要因素之一。基膜的厚度越厚,FO过程中渗透效率越低。制得PSF中空纤维正渗透膜的厚度为0.129 mm,断裂拉伸力为2.48 N,FO通量为10.3 L·m^-2·h^-1,逆向盐扩散性能为0.15 g·L^-1。