Preparation and characterization of poly(methyl methacrylate)/titanium oxide composite particles

Before polymerization, the introduction of double bonds onto the surface of the TiO₂ particles was achieved by the treatment of the TiO₂ particles with the silane-coupling agent. Via in-situ emulsion polymerization, the poly(methyl methacrylate) (PMMA)/titanium oxide (TiO₂) composite particles were prepared by graft polymerization of MMA from the surface of the modified TiO₂ particles. The structure of the obtained PMMA/TiO₂ composite particles was characterized using fourier transform infrared spectra (FT-IR), thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC) and size excluding chromatography (SEC). The morphology of the obtained PMMA/TiO₂ composite particles was observed by transmission electron microscope (TEM). The results of FT-IR and TGA measurements show that PMMA is successfully grafted from the surface of the TiO₂ particles and that the percentage of grafting and the grafting efficiency can reach 208.3% and 96.6%, respectively. At the same time, the TGA and DSC measurements indicate an enhancement of thermal stability. TEM images demonstrate a better dispersion of the TiO₂ particles in the composite latex. In addition, UV-visible absorption measurements show that the PMMA/TiO₂ composite particles can absorb over 95% UV light at 210–400 nm wavelength.     

TiO2/聚丙烯酸丁酯纳米复合薄膜的制备及结构表征

利用微乳液原位聚合法在普通玻璃表面上制备了TiO2/聚丙烯酸丁酯纳米复合膜.采用傅立叶变换红外光谱、高分辨透射电子显微镜和X射线光电子能谱对膜的结构进行了表征.结果表明， TiO2以纳米线的形式弥散在聚丙烯酸丁酯的高分子网络中，并且所制备的TiO2纳米线具有板钛矿相结构.     

Synthesis and characterization of core-shell polyacrylate particles containing hindered amine light stabilizers

A polymerizable hindered amine light stabilizer (HALS) 1,2,2,6,6-pentamethylpiperidin-4-yl acrylate (PMPA) was synthesized through transesterification of 1,2,2,6,6-pentamethylpiperidin-4-ol (PMP) with methyl acrylate (MA). Core-shell latex particles containing HALS moieties in the shell phase were prepared by two-stage seeded emulsion polymerization from n-butyl acrylate (BA), methyl methacrylate (MMA) and PMPA. The Fourier transformed infrared (FTIR) and nuclear magnetic resonance (¹H NMR) analysis showed that PMPA monomer was successfully prepared and was effectively involved in the polyacrylate particles. The surface composition was studied by X-ray photoelectron spectroscopy (XPS), and the results indicated that HALS-containing groups could be distributed on the surfaces of the particles. Transmission electron microscopy (TEM) analysis revealed that the particles obtained presented a core-shell structure with a particle size around 100 nm. Two glass transition temperatures (T_g), assigned to the core phase and the shell phase of the particles, respectively, were observed for both HALS-containing and HALS-free particles, as determined by differential scanning calorimetry (DSC). In addition, the T_g value for the shell phase of HALS-containing particles was 13 °C lower than that of HALS-free particles, indicating the presence of random copolymer between MMA monomer and PMPA comonomer in the shell phase. The thermogravimetry analysis (TGA) and differential thermal gravimetric (DTG) results showed that HALS-containing particles provided an improvement in thermal stability in comparison to HALS-free particles.     

种子乳液聚合方法制备聚苯乙烯－聚硅氧烷核壳粒子

采用种子乳液聚合的方法，制备以聚苯乙烯为壳、聚有机硅氧烷为核的弹性粒子，探讨了加料和引发方式对粒子的结构及形貌的影响，并对苯乙烯种子乳液聚合的机理进行了初步的讨论。     

Preparation of ASA (acrylonitrile-styrene-acrylate) structural latexes via seeded emulsion polymerization

Acrylonitrile-styrene-acrylate (ASA) structural latexes were synthesized in a two-stage seeded emulsion polymerization. In the first-stage, partially cross-linked poly (n-butyl acrylate) (PnBA) and poly (n-butyl acrylate-stat-2-ethyl hexyl acrylate) P (nBA-stat-2EHA) (75/25 by wt) rubber cores were synthesized, and then in the second-stage, a hard poly (styrene-stat-acrylonitrile) (SAN) (70/30 by wt) shell was grafted on to the rubber seeds. The effects of surfactant type and second-stage monomer addition mode have been investigated on the final morphology of two-stage emulsion particles. The results indicated that an application of anionic surfactant, that is, sodium dodecyl sulfonate (SDS), along with sodium persulfate (KPS) initiator for both stages, and with first-stage tert-butyl hydroperoxide (t-BHP) and second-stage KPS initiators led to a hemisphere particle morphology. On the other hand, raspberry and core-shell structures were observed for the structural latexes, which were prepared using a non-ionic surfactant, that is, nonylphenol ethoxylated polyethylene glycol (Igepal CO-850), accompanying KPS initiator for both stages. It is clear, however, that the relative surface hydrophilicity of the core phase, altered by the surfactant type considerably affected the type of morphology formed. For obtained structural latexes, the gradual addition of the second-stage monomers to the core latexes resulted in a fairly real core-shell structure with a higher shell thickness. On the contrary, a raspberry structure in which the rubber phase was enlarged by the second-stage polymer microdomains was observed for the second-stage monomer addition batch. In fact, the shell semi-batch polymerization conditions lower the shell plasticizing effect, and increase the kinetic barrier to prevent from further second-stage monomer diffusion and microdomain formation within the rubbery phase.     

聚氯甲基苯乙烯纳米乳胶粒子的制备

聚氯甲基苯乙烯纳米乳胶粒子的制备;聚氯甲基苯乙烯;纳米乳胶粒子;乳液聚合     

Preparation,characterization and application of a novel thermal stable composite nanofiltration membrane

A thermal stable composite membrane was prepared by interfacial polymerization of piperazine (PIP) and trimesoyl chloride (TMC) on poly(phthalazinone ether amide) (PPEA) ultrafiltration membrane. The effect of reaction parameters on the performance of composite membranes was studied and optimized. The surface morphologies of the composite membrane and the substrate were observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The rejection of optimized composite membrane for dyes Congo red (CGR) and Acid chrome blue K (ACBK), the molecular weight (MW) of which is over 400, was over 99.2%, with a flux at about 180 L m⁻² h⁻¹. While the rejection for NaCl was only 18.2% with a flux over 270 L m⁻² h⁻¹, when tested at 1.0 MPa 60 °C. The composite membrane was applied in the desalination-purification experiment of dye ACBK and NaCl mixed solution. The flux of the membrane increased obviously as the operation pressure and/or temperature increased, while the rejection for dye was constant and kept over 99.3%. The purification experiments were accomplished effectively at 1.0 MPa, 80 °C. Only after five rounds of desalination-concentration experiment, about 160 min, the salt mixed in dye solution was fully removed. The initial flux of the eighth cycle was about 254 L m⁻² h⁻¹, which was only 20 L m⁻² h⁻¹ lower than that of the first round. The rejection of the membrane was constant and kept over 99.3% through out the eight cycles of purification experiment.     

Polypropylene/poly(butyl methacrylate) blends prepared by diffusion and subsequent polymerization of butyl methacrylate in isotactic polypropylene pellets

Polypropylene/poly(butyl methacrylate)(PP/PBMA) blends were prepared by diffusion and subsequent polymerization of butyl methacrylate(BMA) in commercial isotactic polypropylene(iPP) pellets.The diffusion kinetics,diametrical distribution of PBMA in a pellet and phase morphology of a typical PP/PBMA blend were investigated.     

浓乳液双相聚合方法制备异形聚合物粒子

采用浓乳液双相聚合方法,成功制备了聚丙烯酸丁酯(PBA)的异形粒子,通过在连续相中引入聚合物隔层,大大提高了浓乳液聚合过程中的稳定性,探讨了隔层种类对浓乳液稳定性的影响,并研究了浓乳液分散相体积分数和交联剂用量对PBA粒子异形程度的影响,并结果表明,浓乳液双相聚合过程中,分散相体积分数越高,交联剂用量越高,PBA粒子的异形程度越大。     

Synthesis and Characterization of Large Dimension PBA-P(MMA-ITA) Latex Particles with Core-Shell Morphology

In this paper, a novel large dimension poly(n-butyl acrylate)-poly(methyl methacrylate-itaconic acid) (PBA-P(MMA-ITA)) core-shell latex particles (CSR) with diameter of 200 nm～300 nm were successfully synthesized via pre-emulsion and semi-continuous seeded emulsion polymerization process. The analysis on the surface tension and coagulation rate of polymeric system, size and distribution of latex particles indicated that the composite emulsifier of sodium dodecyl sulfonate/polyoxyethylene nonyl phenyl ether (SDS/OP-10) had the best emulsified effect. The optimal ratio of SDS/OP-10 was 1:1 and its optimum dosage was 1.0% of monomer amount. FTIR analysis results confirmed that ITA participated in the copolymerization reaction and the chemical bond between P(MMA-ITA) copolymer and PBA core existed in the interfacial of core and shell. DSC analysis results showed that the glass transition temperature (T _g) of P(MMA-ITA) copolymer increased with the increase of the ITA dosage and decreased with the increase of the core shell mass ratio. TEM images revealed that CSR particles had core-shell morphology indeed, but the particles’ core-shell morphology would be changed at higher ITA dosage and core shell mass ratio. The size of CSR particles was 330 nm, and the diameter of PBA core was 290 nm. ITA content in the shell of CSR particles was analyzed by non-aqueous acid-base titration. ITA content was the highest at 6% of ITA dosage, ITA amount which chemically bonded with PBA core was the highest at 8% of ITA dosage. When the core shell mass ratio was 60/40, ITA content and ITA amount which grafted onto PBA core were both the highest. ITA content of CSR particles achieved above 1.11% in this work, and it is completely possible for using CSR particles toughening and compatibilizing polyamide 6 (PA 6).     

TiO2/聚丙烯酸丁酯纳米复合膜的制备及摩擦性能

二氧化钛;TiO2/聚丙烯酸丁酯纳米复合膜的制备及摩擦性能     

Polystyrene latices containing dodecanamide‐modified poly(propyleneimine) dendrimers

Polymerization of styrene in aqueous dispersions of the dodecanamide derivative of poly(propyleneimine) dendrimer DAB‐dendr‐(NH₂)₆₄ and sodium dodecyl sulfate (SDS) produced stable latices. With initial SDS concentrations of 10 mM or less, molar ratios of SDS to dendrimer end groups ranging from 2.3:1 to 9.5:1, and less than 10 wt % of SDS relative to styrene, the polystyrene latices had diameters of 30–60 nm and coefficients of variation of diameters of less than 10% when measured by transmission electron microscopy. Higher concentrations of SDS gave more polydisperse latices. The polystyrene latices formed with SDS and the dodecanamide‐modified dendrimer were almost the same size and polydispersity as those formed with SDS and the parent primary amine dendrimer DAB‐dendr‐(NH₂)₆₄. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 597–605, 2003     

单分散聚丙烯酸丁酯-二氧化硅核壳粒子的制备

近年来,有机-无机核壳材料因其具有可调的光、电、磁等特性而备受关注．无机物外壳可以增强粒子的热力学稳定性、机械强度和抗拉性能．高分子乳胶粒内核具有弹性,且易成膜,外部包覆无机物的乳胶粒可结合两者特性并产生协同效应．     

Preparation, characterization and curing properties of epoxy-terminated poly(alkyl-phenylene oxide)s

A series of dihydroxyl telechelic poly(alkyl-phenylene oxide)s (1) have been synthesized by oxidative polymerization of alkylphenols with various aromatic diols using manganese or copper amine catalysts. The novel telechelic derivatives (1) were epoxidized with epichlorohydrin yielding a series of new epoxidized poly(alkyl-phenylene oxide)s (EPPO, 2) and the structures, properties were studied by nuclear magnetic resonance spectroscopy (NMR), differential scanning calorimetry (DSC), thermo gravimetric analysis (TGA) and gel permeation chromatography (GPC). The 1:1 blends of diglycidyl ether of bisphenol-A (DGEBA) with EPPO resins were cured with three curing agents and the effects of chemical structure change on thermal property of the curing matrixes were discussed. Incorporation of EPPOs to DGEBA epoxy system resulted in a significant increase in its glass transition temperature (T_g), thermal stability and flame resistance. The T_g values and char yields arising from a DDM-cured epoxy resin are usually higher than those of dicyandiamide (DICY) or 2-methylimidazole (2-MI) analogues and the reactivity of epoxy blends with three curing agents presents an increase in the order of 2-MI, DDM and DICY. In general, the tetramethylbisphenol-A (TMBPA)-derived polymer exhibits the lowest T_g, char yield and dielectric constant among PPO derivatives whereas the biphenol polymers usually results in higher T_g and char yield due to its rigid rod structure.     

Synthesis,Characterization and Application of Amphiphilic Copolymer Poly(vinyl alcohol)-g-Poly(butyl acrylate)

An amphiphilic graft copolymer poly(vinyl alcohol)-g-poly(butyl acrylate) (PVA-g-PBA) was synthesized by grafting butyl acrylate (BA) onto poly(vinyl alcohol) (PVA) with potassium persulfate (KPS) as free radical initiator in N₂ atmosphere and aqueous medium. The formation of graft copolymer was confirmed by means of infrared spectroscopy (IR). The influences of initiator, monomer concentration and reaction time on the percentage of monomer conversion(C _M), graft degree(Gd) and graft efficiency(Ge) have been discussed in detail. PVA-g-PBA was used as compatibilizer in blends of chlorinated polyethylene (CPE)/ poly(acrylic acid-co-acrylamide)[P(AA-AM)], and the compatibility between CPE and P(AA-AM) was also investigated.     

Synthesis and properties of soap-free poly(methyl methacrylate-ethyl acrylate-methacrylic acid) latex particles prepared by seeded emulsion polymerization

In order to obtain functional polymer latex particles with clean surface and with surface carboxyl groups, P(MMA-EA) seed particles with the diameter of 335 nm were first synthesized via soap-free batch emulsion polymerization of methyl methacrylate (MMA) and ethyl acrylate (EA), and then the seeded emulsion copolymerization of MMA, EA and MAA (methacrylic acid) onto the seed particles were performed in the absence of emulsifier. Influences of ingredients and conditions on polymerization, latex particle size (D_p) and its distribution were investigated. Results showed that most of the monomers polymerized onto the seed latex particles in the second step of polymerization by using drop-wise addition method, and D_p increased from 483 nm to 829 nm with the mass ratio of core/shell monomers [C]/[S] decreased from 1:2 to 1:15. It was found that D_p decreased with the increase of MAA and initiator amounts, and the size of the latex particles became uniform with the decrease of MAA amount and with the increase of [C]/[S] value.     

Studies on synthesis and properties of poly(ferrocenyldimethylsilanes) and poly(ferrocenylmethylphenylsilanes)

Poly(ferrocenyldimethylsilane) and poly(ferrocenylmethylphenylsilane) have been prepared via the thermal ring-opening polymerization of the corresponding strained, silicon-bridged ferrocenophanes. It was found that the molecular weights of resultant polymers depend on the polymerization time. Their electrochemical behavior in aqueous electrolytes was investigated by cyclic voltammetry.     

Preparation of polymer particles having ethyleneurea groups at their surfaces by emulsifier-free seeded emulsion polymerization and wet adhesion of its emulsion film

Polymer emulsion having ethyleneurea groups at particle surfaces was produced by emulsifier-free seeded emulsion copolymerization of n-butyl methacrylate (BMA) and methacrylamide ethylethyleneurea (EU) with poly(BMA) seed particles utilizing the starved-fed monomer addition method. This emulsion film, prepared by casting the polymer emulsion on an alkyd resin plate, had a superior adhesion in water, as well as on stainless steel. Such superior wet adhesions seem to be based on a large amount of EU predominantly localized at the particle surfaces.Part CCXLIX of the series "Studies on suspension and emulsion"     

Amphoteric initiators suitable for emulsifier-free emulsion polymerization and the properties of the resulting latices

The soap-free emulsion polymerizations of styrene (St) and acrylamide (AAm) or methyl methacrylate (MMA) were carried out in the presence of three kinds of amphoteric initiators, and the polymerization kinetics and the colloidal properties of the latices produced were emphatically investigated. It was found that the number of carbon atoms between the amidino and carboxyl groups in each initiator exhibited an appreciable effect on the dissociation as well as on the solubility of the initiator in water, and therefore, that the properties of the colloidal particles depended on the structure of the initiators used. All the copolymerization runs, except for the polymerization using 2,2′-azobis(N-(2-caboxyethyl)-2-methylpropionamidine) under a strongly alkali condition, gave amphoteric latices, which indicated higher critical flocculation concentrations at lower or higher pHs than at a medium pH. The surface charge density measured by titration for poly(St/MMA) particles was about 3–10 times as high as that for the poly(St/AAm) ones, though these were prepared under the same conditions other than the monomer composition. The influence of the polymerization pH on both the polymerization rate and the surface charge density of the resulting latices was negligible even if the constants of the decomposition rate and the dissociation of the amphoteric initiators strongly depended on the pH of the medium. Received: 28 July 2000 Accepted: 1 November 2000     

Reverse atom transfer radical polymerization of butyl methacrylate in a miniemulsion stabilized with a cationic surfactant

The miniemulsion reverse atom transfer radical polymerization of butyl methacrylate was carried out with cetyltrimethylammonium bromide (CTAB) as the sole surfactant. The polymerizations were initiated with 2,2′‐azobis[2‐(2‐imidazolin‐2‐yl)propane] dihydrochloride and mediated with copper(II) bromide/tris[2‐di(2‐ethylhexyl acrylate)aminoethyl]amine. The living character was demonstrated by the linear increase in the number‐average molecular weight with conversion and the decreasing polydispersity index with conversion. The polymerizations were conducted at 90 °C with 1 wt % CTAB with respect to the monomer and produced a coagulum‐free latex with a mean particle diameter of 155 nm. The resulting latexes exhibited good shelf‐life stability. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1628–1634, 2006