Non-aqueous polymer dispersions: radical dispersion polymerization in the presence of the diblock copolymer poly(styrene-b-[ethylene-co-propylene])

Radical dispersion polymerizations of monomers, for example methyl methacrylate and vinyl acetate, in n-alkanes were performed in the presence of the diblock copolymer poly(styrene-b-[ethylene-co-propylene]), giving polymer particles stabilized by surface layers of chains of ethylene-propylene copolymer. The incorporation of a seed stage into the dispersion polymerization produced particles having a narrow size distribution. The mean particle diameter in the range 0.1 – 0.3 m is dependent on the concentration of diblock copolymer in the dispersion polymerization.     

Graft copolymerization of butyl acrylate and 2‐ethyl hexyl acrylate from labile chlorines of poly(vinyl chloride) by atom transfer radical polymerization

Trace amounts of labile chlorines present in poly(vinyl chloride) (PVC) were found to act as initiation sites for the preparation of graft copolymers of PVC by copper‐mediated atom transfer radical polymerization (ATRP). High grafting yields were attained during the graft copolymerizations of n‐butyl acrylate (161.8%) and 2‐ethyl hexyl acrylate (51.2%) in 7.5 h. In both cases, the grafting proceeded with first‐order kinetics with respect to the monomer concentrations, this being typical for ATRP. Gel permeation chromatography traces of the resulting products did not exhibit additional peaks attributable to the formation of free homopolymers. The presented procedure offers an efficient means of preparing self‐plasticized PVC structures. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3457–3462, 2003     

聚甲基丙烯酸甲酯与聚醋酸乙烯酯共混的红外光谱研究

用红外光谱(FTIR)研究了聚甲基丙烯酸甲酯(PMMA)与聚醋酸乙烯酯(PVAc)共混体系相容性,在160℃以上共混体系发生相分离;分相体系与非分相体系的FTIR谱明显不同;共混体系的FTIR谱不能从两统组分红外光谱简单加和得到;结果表明大分子构象发生了变化,PMMA/PVAc体系相容可能是大分子构象熵变所致。     

Synthesis of carbosilane block copolymers by means of a living anionic polymerization of 1,1-diethylsilacyclobutane

Block polymerization of 1,1-diethylsilacyclobutane with styrene derivatives and methacrylate derivatives was investigated. Sequential addition of styrene to a living poly(1,1-diethylsilabutane), which was prepared from phenyllithium and 1,1-diethylsilacyclobutane in THF–hexane at −48°C, gave poly(1,1-diethylsilabutane)-b-polystyrene. Similarly, addition of 4-(tert-butyldimethylsiloxy)styrene to the living poly(1,1-diethylsilabutane) provided poly(1,1-diethylsilabutane)-b-poly(4-(tert-butyldimethylsiloxy)styrene). Poly(1,1-diethylsilabutane)-b-poly(methyl methacrylate) was obtained by treatment of living poly(1,1-diethylsilabutane) with 1,1-diphenylethylene followed by an addition of methyl methacrylate. Poly(1,1-diethylsilabutane)-b-poly(2-(tert-butyldimethylsiloxy)ethyl methacrylate) was also synthesized by adding 2-(tert-butyldimethylsiloxy)ethyl methacrylate to the living poly(1,1-diethylsilabutane) which was end-capped with 1,1-diphenylethylene in the presence of lithium chloride. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2699–2706, 1998     

非共价修饰碳纳米管/二氧化钛复合材料的合成及性能

采用溶胶-凝胶法在聚乙烯吡咯烷酮(PVP)非共价修饰的碳纳米管表面均匀沉积二氧化钛粒子制得纳米复合材料。用TEM、XRD、FTIR、N2吸脱附等对复合材料进行了表征。结果表明:纳米二氧化钛纳米粒子均匀沉积在被修饰碳纳米管表面,且二氧化钛为纯锐钛矿晶体结构,没有金红石和板钛矿相。非共价修饰碳纳米管/二氧化钛复合材料具有良好的介孔结构,其孔径分布主要集中在6～10 nm,且比表面积与纯的二氧化钛相比明显增大,在紫外光照射下降解亚甲基蓝,相比纯的二氧化钛和碳纳米管/二氧化钛,具有较高的催化活性。     

Thermal and photochemical stability of poly(methyl methacrylate) and its blends with poly(vinyl acetate)

An investigation of the thermal stability of poly(methyl methacrylate) (PMMA) blends with poly(vinyl acetate) (PVAc) revealed that PVAc acts as a stabilizer as concerns thermal and photochemical degradation when the processes take place in air. The temperatures of decomposition of these blends are higher than that of pure PMMA. The efficiency of photodegradation and photooxidation in the blends is lower than that of pure PMMA.     

Sequence distribution of PMMA/iBuA copolymer by incremental calculation of 13C NMR spectra

An incremental method for characterizing triad and pentad distribution by ¹³C NMR spectroscopy was applied to the poly(methyl methacrylate-co-isobutyl acrylate) copolymer. Calculation of the intensity of individual lines was performed applying Bernoulli statistics, while the chemical shifts for each sequence were calculated by an incremental method. Based on these data, the carbonyl signal was simulated yielding good agreement at the triad and pentad level.     

Multimonomer and cross-linked polymers formed by its copolymerization

Differential scanning calorimetry (DSC) and thermogravimetry (TG) were used to examine the thermal behavior of the multimonomer poly[2-(10-undecenoyloxy)ethyl methacrylate] (PUDEM) within the temperature range from -80 to 400°C. DSC measurements indicated that the polymer side chains were able to crystallize in paraffinic phase. PUDEM, added to methyl methacrylate (MM), can effectively copolymerize with essentially no homopolymer produced as shown by DSC (single T _g). The value of T _g depends on the PUDEM content, degree of cross-linking and the presence of free MM in the cross-linked product. This revised version was published online in August 2006 with corrections to the Cover Date.     

Graft copolymers of polyethylene by atom transfer radical polymerization

Poly(ethylene‐g‐styrene) and poly(ethylene‐g‐methyl methacrylate) graft copolymers were prepared by atom transfer radical polymerization (ATRP). Commercially available poly(ethylene‐co‐glycidyl methacrylate) was converted into ATRP macroinitiators by reaction with chloroacetic acid and 2‐bromoisobutyric acid, respectively, and the pendant‐functionalized polyolefins were used to initiate the ATRP of styrene and methyl methacrylate. In both cases, incorporation of the vinyl monomer into the graft copolymer increased with extent of the reaction. The controlled growth of the side chains was proved in the case of poly(ethylene‐g‐styrene) by the linear increase of molecular weight with conversion and low polydispersity (M_w /M_n < 1.4) of the cleaved polystyrene grafts. Both macroinitiators and graft copolymers were characterized by ¹H NMR and differential scanning calorimetry. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2440–2448, 2000     

TEMPO-mediated radical polymerization in the synthesis of poly(methyl methacrylate) macromonomer

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Direct and inverse neural network modeling in free radical polymerization

The first part of this paper reviews of the most important aspects regarding the use of neural networks in the polymerization reaction engineering. Then, direct and inverse neural network modeling of the batch, bulk free radical polymerization of methyl methacrylate is performed. To obtain monomer conversion, number and weight average molecular weights, and mass reaction viscosity, separate neural networks and, a network with multiple outputs were built (direct neural network modeling). The inverse neural network modeling gives the reaction conditions (temperature and initial initiator concentration) that assure certain values of conversion and polymerization degree at the end of the reaction. Each network is a multi-layer perceptron with one or two hidden layers and a different number of hidden neurons. The best topology correlates with the smallest error at the end of the training phase. The possibility of obtaining accurate results is demonstrated with a relatively simple architecture of the networks. Two types of neural network modeling, direct and inverse, represent possible alternatives to classical procedures of modeling and optimization, each producing accurate results and having simple methodologies.     

Poly(meth)acrylate grafted EPDM via reverse atom transfer radical polymerization: A single pot process

This investigation reports a one pot preparation of poly(meth)acrylate grafted EPDM via reverse ATRP and evaluation of their physical and mechanical properties. The graft copolymerization of 2-ethylhexyl acrylate and methyl methacrylate was carried out from EPDM using reverse ATRP in toluene at 90 °C using CuBr₂ as catalyst in combination with PMDETA as ligand and AIBN as thermal initiator. The grafted EPDMs were separated from the reaction mixture, purified and then characterized by FT-IR, ¹H NMR, DMA and TGA analyses. Surface energies and tensile properties were evaluated by Goniometer and UTM respectively. Acrylate grafted EPDMs showed better thermal stability, better tensile property, whereas methacrylate grafted EPDMs showed higher surface energy and better oil resistance property than the pristine EPDM. Surface morphologies of grafted EPDMs were analyzed by AFM and SEM analyses. This one pot grafting approach led to very high grafting percentage without undesirable homopolymerization and gelation.     

Synthesis of novel crosslinkable polymers by atom transfer radical polymerization of cardanyl acrylate

In this work, the successful application of atom transfer radical polymerization (ATRP) to cardanyl acrylate, a polymerizable monomer derived from a renewable resource cardanol, is reported. Polycardanyl acrylate and poly(methylmethacrylate)‐cardanyl acrylate copolymers were prepared in bulk ATRP, using Copper(I) bromide/N, N, N′, N′, N″‐pentamethyl diethylene triamine (PMDETA) catalyst system at 95 °C in combination with ethyl‐2‐bromo isobutyrate initiator. The copolymers had mol. wt. (M_n) in the range 8300–2400 g/mol and polydispersity index (PDI) 1.27–2.00, depending upon the [M]₀/[I]₀ ratio. ¹H NMR analysis of the copolymer showed that unsaturation in the side chain of cardanyl acrylate is unaffected under the conditions of ATRP. This was further confirmed by studying the curing reaction of polycardanyl acrylate by supported dynamic mechanical thermal analysis (DMTA) in dual cantilever mode. The thermogravimetric analysis shows that the copolymers have improved thermal stability, by about 35 °C, in comparison with pure PMMA. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5953–5961, 2005     

Synthesis and characterization of well-defined poly(methyl methacrylate)/CaCO3/SiO2 three-component composite particles via reverse atom transfer radical polymerization

The attempt to prepare structurally well-defined polymer/inorganic composite particles, i.e., poly(methyl methacrylate) (PMMA)/CaCO₃/SiO₂ three-component composite particles, via reverse atom transfer radical polymerization (ATRP), using 2-2′-azo-bis-isobutyronitrile as initiator and Cu(II) bromide as catalyst was reported. CaCO₃/SiO₂ two-component composite particles were first obtained through sol–gel method, and their morphology and surface element information were determined by transmission electron microscopy and X-ray photoelectron spectroscopy, respectively. The results indicate that the CaCO₃ was encapsulated by the obtained SiO₂. After being modified by silane coupling agent, the CaCO₃/SiO₂ composite particles copolymerized with methyl methacrylate (MMA) under standard reverse ATRP conditions to produce PMMA/CaCO₃/SiO₂ three-component composite particles. In the case concerned, first-order kinetic plots and linear increase of molecular weight (Mn) vs conversion and narrow molecular weight distribution for the graft polymer samples were observed. Furthermore, the gel permeation chromatography results illustrated that both the free PMMA chains from the solvent and the graft PMMA chains from the surface of CaCO₃/SiO₂ two-component composite particles were growing at the same rate. Characterizations of the PMMA-grafted CaCO₃/SiO₂ composite particles were done by Fourier transform infrared and thermogravimetric analysis. The results showed that the surface of the modified inorganic particles was grafted by the MMA and that the grafting percentage was about 8.7%.     

Densification of Sol-Gel Thin Films by Ultraviolet and Vacuum Ultraviolet Irradiations

Structural changes in SiO₂ and TiO₂ gel films were investigated using ultraviolet (UV) and vacuum ultraviolet (VUV) irradiations. A significant compaction with dehydration of SiO₂ gel films was induced by irradiation of photons in the range of 9–18 eV. The refractive index and the shrinkage of the irradiated SiO₂ gel films were comparable to those obtained by sintering at 1000°C. Densification of TiO₂ gel films was also observed with irradiation of 5–14 eV photons. However, effects of the irradiation on TiO₂ gel were smaller that those on SiO₂ gel. The structural changes in the gel films are attributed to electronic excitations which are induced by irradiation with photons having higher energies than the bandgap of the oxides. The photo-induced effects are presumed to depend on the optical properties and structure of the gels.     

A degradable atom transfer radical polymerization inimer: Synthesis,polymerization, and cleavage of the resulting polymer products

A novel degradable inimer for atom transfer radical polymerization (ATRP), 2‐(6‐(2‐((2‐bromo‐2‐methylpropanoyl)oxy)ethyl)pyridin‐2‐yl)ethyl methacrylate (PyDEBrMΑ), was synthesized by the two‐step esterification of 2,6‐pyridinediethanol, first with α‐bromoisobutyryl bromide in order to introduce the initiator moiety, and then with methacryloyl chloride in order to introduce the monomer moiety. PyDEBrMA was subsequently used to initiate the self‐condensing ATRP of methyl methacrylate (MMA) to obtain a hyperbranched MMA homopolymer which could be cleaved at the PyDEBrMA residue either by treatment under mildly alkaline hydrolysis conditions (sodium deuteroxide in d₆‐DMSO at room temperature) or thermolysis at 150 °C. The lability of the PyDEBrMA residue arises from the presence in its structure of two 2‐(pyridin‐2‐yl)ethyl ester moieties. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2831–2839     

Synthesis and characterization of oxazoline-functional polymer particles by free radical nonaqueous dispersion polymerization

A novel oxazoline-functional methacrylate was prepared and employed as comonomer to produce nonaqueous dispersions of oxazoline-functional polymer particles. In nonaqueous free radical dispersion copolymerization of methylmethacrylate in the presence of oxazoline-functional methacrylate, ethyleneglycoldimethacrylate crosslinking agent, AIBN initiator, and polystyrene-block-poly(ethene-alt-propene) dispersing agent, the average polymer particle size, varying between 100 and 500 nm, was controlled by the dispersing agent contents. According to titration with HClO₄ all oxazoline groups regardless of their location at particle surface or bulk, were accessible. Glass transition temperature decreased from 120 to 0°C when oxazoline functional methacrylate was increased from 0 to 95 mol %. As imaged by atomic force microscopy incorporation of the new oxazoline-functional methacrylate improved film formation. Oxazoline-functional polymer particles were easy to redisperse in a variety of other diluents. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 2539–2548, 1997     

Intimate blending of binary polymer systems from their common cyclodextrin inclusion compounds

A procedure for the formation of intimate blends of three binary polymer systems polycarbonate (PC)/poly(methyl methacrylate) (PMMA), PC/poly(vinyl acetate) (PVAc) and PMMA/PVAc is described. PC/PMMA, PC/PVAc, and PMMA/PVAc pairs were included in γ‐cyclodextrin (γ‐CD) channels and were then simultaneously coalesced from their common γ‐CD inclusion compounds (ICs) to obtain intimately mixed blends. The formation of ICs between polymer pairs and γ‐CD were confirmed by wide‐angle X‐ray diffraction (WAXD), fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). It was observed [solution ¹H nuclear magnetic resonance (NMR)] that the ratios of polymers in coalesced PC/PMMA and PC/PVAc binary blends are significantly different than the starting ratios, and PC was found to be preferentially included in γ‐CD channels when compared with PMMA or PVAc. Physical mixtures of polymer pairs were also prepared by coprecipitation and solution casting methods for comparison. DSC, solid‐state ¹H NMR, thermogravimetric analysis (TGA), and direct insertion probe pyrolysis mass spectrometry (DIP‐MS) data indicated that the PC/PMMA, PC/PVAc, and PMMA/PVAc binary polymer blends were homogeneously mixed when they were coalesced from their ICs. A single, common glass transition temperature (T_g) recorded by DSC heating scans strongly suggested the presence of a homogeneous amorphous phase in the coalesced binary polymer blends, which is retained after thermal cycling to 270 °C. The physical mixture samples showed two distinct T_gs and ¹H T_1ρ values for the polymer components, which indicated phase‐separated blends with domain sizes above 5 nm, while the coalesced blends exhibited uniform ¹H spin‐lattice relaxation values, indicating intimate blending in the coalesced samples. The TGA results of coalesced and physical binary blends of PC/PMMA and PC/PVAc reveal that in the presence of PC, the thermal stability of both PMMA and PVAc increases. Yet, the presence of PMMA and PVAc decreases the thermal stability of PC itself. DIP‐MS observations suggested that the degradation mechanisms of the polymers changed in the coalesced blends, which was attributed to the presence of molecular interactions between the well‐mixed polymer components in the coalesced samples. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2578–2593, 2005     

Synthesis and characterization of block copolymers from 2‐vinylnaphthalene by anionic polymerization

The anionic polymerization of 2‐vinylnaphthalene (2VN) has been studied in tetrahydrofuran (THF) at ?78 °C and in toluene at 40 °C. 2VN polymerization in THF, toluene, or toluene/THF (99:1 v/v) initiated by sec‐butyllithium (sBuLi) indicates living characteristics, affording polymers with predefined molecular weights and narrow molecular weight distributions. Block copolymers of 2VN with methyl methacrylate (MMA) and tert‐butyl acrylate (tBA) have been synthesized successfully by sequential monomer addition in THF at ?78 °C initiated by an adduct of sBuLi–LiCl. The crossover propagation from poly(2‐vinylnaphthyllithium) (P2VN) macroanions to MMA and tBA appears to be living, the molecular weight and composition can be predicted, and the molecular weight distribution of the resulting block copolymer is narrow (weight‐average molecular/number‐average molecular weight < 1.3). Block copolymers with different chain lengths for the P2VN segment can easily be prepared by variations in the monomer ratios. The block copolymerization of 2VN with hexamethylcyclotrisiloxane also results in a block copolymer of P2VN and poly(dimethylsiloxane) (PDMS) contaminated with a significant amount of homo‐PDMS. Poly(2VN‐b‐nBA) (where nBA is n‐butyl acrylate) has also been prepared by the transesterification reaction of the poly(2VN‐b‐tBA) block copolymer. Size exclusion chromatography, Fourier transform infrared, and ¹H NMR measurements indicate that the resulting polymers have the required architecture. The corresponding amphiphilic block copolymer of poly(2VN‐b‐AA) (where AA is acrylic acid) has been synthesized by acidic hydrolysis of the ester group of tert‐butyl from the poly(2VN‐b‐tBA) copolymer. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4387–4397, 2002