Preparation and properties of PVC/PMMA-g-imogolite nanohybrid via surface-initiated radical polymerization

Poly(methyl methacrylate) (PMMA) grafted imogolite clay nanotubes (PMMA-g-imogolite) were prepared through activators regenerated by electron transfer for atom transfer radical polymerization (ARGET ATRP) by developing a water soluble amphiphilic ATRP initiator, which carries both an initiator moiety and a surface-attachable phosphate group. Poly(vinyl chloride)/PMMA-g-imogolite nanohybrid was prepared by using this PMMA grafted imogolite. The structure and properties of the prepared nanohybrid were characterized by differential scanning calorimetry (DSC), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and tensile test. DSC and TEM results indicate that well-dispersed PMMA-g-imogolite dominates in the nanohybrid, in spite of some imogolite rich regions. SEM observation of the fracture surfaces and the fractured films reveals that the interfacial adhesion between PMMA grafted imogolite and the matrix may be weak or strong with respect to the cohesive energy of the poly(vinyl chloride) (PVC) matrix, depending on the environmental temperature. In liquid nitrogen or at room temperature, the interfacial adhesion between PMMA grafted imogolite and the matrix is weaker, while at 90 °C, is stronger than the cohesion of the PVC matrix. In accordance with the interfacial performance, the nanohybrid shows inferior tensile performance at room temperature; whereas, superior tensile performance at 90 °C compared with the pristine PVC.     

Grafting polymer from poly(ethylene terephthalate) films by surface‐initiated ATRP

Surface‐initiated atom transfer radical polymerization (ATRP) from poly(ethylene terephthalate) (PET) film was studied. Poly(methyl methacrylate) (PMMA), poly (acrylamide) (PAAM), and their diblock copolymer (PMMA/PAAM) on the surface of PET film were successfully prepared by surface‐initiated ATRP. The structures and properties of the modified PET film were characterized by FT‐IR/ATR, X‐ray photoelectron spectroscopy (XPS), measurements of contact angles, and scanning electronic microscopy (SEM). The results indicate that the surface properties of PET film were greatly improved by grafted polymer. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

PMMA/PEG共混物形态和热性质的研究

在聚乙二醇存在的情况下,自由基聚合得到的聚甲基丙烯酸甲酯/聚乙二醇(PMMA/PEG)共混物,是一种半结晶聚合物;有相分离发生,一部分PEG晶体依然保持其晶体的特征,另一部分PEG晶体转变成非晶态,与PMMA网络复合,形成完全均一的非晶相。     

Synthesis of amphiphilic diblock copolymers by direct radical polymerization of acrylic acid via DPE method

Amphiphilic diblock copolymers, poly(methyl methacrylate)-b-poly(acrylic acid) (PMMA-b-PAA) was prepared by 1,1-diphenylethene (DPE) method. First, free radical polymerization of methyl methacrylate was carried out with AIBN as initiator in the presence of DPE, giving a DPE-containing PMMA precursor with controlled molecular weight. Amphiphilic diblock copolymer PMMA-b-PAA was then prepared by radical polymerization of acrylic acid (AA) in the presence of PMMA precursor. The formation of PMMA-b-PAA was confirmed by ¹H NMR spectrum and gel permeation chromatography. Transmission electron microscopy and dynamic light scattering were used to detect the self-assembly behavior of the amphiphilic diblock polymers in methanol.     

自由基聚合制备甲基丙烯酸甲酯-苯乙烯嵌段共聚物

以偶氮二异丁腈为引发剂,乙二硫醇（EDT）为链转移剂进行甲基丙烯酸甲酯（MMA）的自由基聚合,得到了含有残余巯基的聚甲基丙烯酸甲酯大分子链转移剂（HS-PMMA）,继而以HS-PMMA作为大分子链转移剂进行苯乙烯的自由基聚合,采用普通自由基聚合方法合成了结构可以设计的嵌段共聚物。     

Deacetylation behavior of binary blend films of cellulose acetate and various polymers

For binary blend films of cellulose acetate (CA) and various polymers, the elution behavior of the polymers from the CA films in different environments (i.e., soil, water) was examined. For the CA film containing poly(ethylene glycol) (PEG), the PEG eluted to the periphery of the film completely. On the other hand, polyvinylpyrrolidone blended with CA remained in the CA film. A CA film containing acrylic acid was prepared, and this film was heated. The elution of acrylic acid was inhibited by its polymerization. These results suggested that the internal polymers were capable of remaining in the CA film by polymer entanglement. Second, we examined the deacetylation and biodegradation behavior of CA films containing polymers with a phosphoric acid moiety in the side chain, such as poly(2‐hydroxyethyl methacrylate phosphoric acid ester) [poly(HEMA‐P)]. Poly(HEMA‐P) had the ability to deacetylate the CA, and the biodegradation rate of the CA films containing poly(HEMA‐P) increased in comparison with that of the nonadditive CA films. The elution of internal 2‐hydroxyethyl methacrylate phosphoric acid ester was inhibited by the copolymerization with 2‐hydroxyethyl methacrylate or crosslinking. In the case of both 2‐hydroxyethyl methacrylate phenyl phosphoric acid ester and 10‐methacryloyloxydecyl dihydrogen phosphate, the acetone‐soluble polymers were obtained by radical polymerization in a mixture of acetone and water. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1816–1823, 2006     

Grafting and properties of a porous poly(methyl methacrylate) film on a silicon surface by a one‐step dipping method

In this study, we prepared a porous poly(methyl methacrylate) (PMMA) film on an Si surface with a novel dipping method. We conducted the process by directly dipping the Si substrate into acidic aqueous media in a simple flask at 10 °C. First, 4‐nitrobenzene diazonium tetrafluoroborate (NBD) was spontaneously reduced at the Si surface. Then, the aryl radicals during the reduction of NBD were directly grafted onto the Si surface. Meanwhile, the aryl radicals initiated the polymerization of methyl methacrylate (MMA) monomers, and the radical‐terminated PMMA chains formed in the solution were grafted onto the Si surface. Because water was a poor solvent for MMA, the grafted PMMA chains easily aggregated together, and this resulted in a porous polymer film. The porosity of the film depended on the grafting time and the MMA concentration. Furthermore, the permittivity of the porous PMMA film was relatively low, and its dielectric dissipation factor was extremely small. Therefore, its excellent dielectric properties should allow the porous film to have many applications in industry. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44930.     

Synthesis of amphiphilic heteroarm star‐shaped polymer via free radical polymerization using polyfunctional chain transfer agent and its self‐assembly behavior

Amphiphilic heteroarm star‐shaped polymers have important theoretical and practical significance. In this work, amphiphilic heteroarm star‐shaped polymer was synthesized by the use of polyfunctional chain transfer agent via sequential free radical polymerization in two steps. First, conventional free radical polymerization of methyl methacrylate (MMA) initiated by 2,2′‐azobis (isobutyronitrile) (AIBN) was carried out in the presence of polyfunctional chain transfer agent, pentaerythritol‐tertrakis (3‐mercaptopropinate) (PETMP). At appropriate monomer conversion, about two‐arm s‐PMMA having two residual thiol groups at the chain center was obtained. Second, the s‐PMMA obtained above was used as macro‐chain‐transfer agent for free radical polymerization of acrylic acid (AA). The heteroarm star‐shaped polymer with the hydrophobic PMMA segment and the hydrophilic PAA segment was obtained. The successful synthesis of heteroarm star‐shaped polymers, (PMMA)₂(AA)₂, was confirmed by ¹H‐NMR and its self‐assembly behavior in different solvents. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis and characterization of PMMA/SiO2 organic–inorganic hybrid materials via RAFT‐mediated miniemulsion polymerization

In this article, we first carried out the surface modification of SiO₂ using silane coupling agent KH570, and then prepared PMMA/SiO₂ organic–inorganic hybrid materials by conventional free radical polymerization and RAFT polymerization in miniemulsion, respectively. The kinetics comparisons of these two polymerizations were studied. PMMA/SiO₂ hybrid materials were characterized by gel permeation chromatography, differential scanning calorimetry and thermogravimetric analysis. Experimental results indicated that the polymerization behavior of MMA in miniemulsion showed controlled/living radical polymerization characteristics under the control of RAFT agent. Incorporation of RAFT agent and SiO₂ nanoparticles improved the thermal properties of polymers, the thermal stability of polymers increased with increasing content of SiO₂ nanoparticles. The structures and morphologies of SiO₂, modified SiO₂, and PMMA/SiO₂ hybrid materials were characterized by FT‐IR and TEM. TEM results showed that the addition of modified SiO₂ nanoparticles to miniemulsion polymerization system obtained different morphology latex particles. Most of modified SiO₂ nanoparticles were wrapped by polymer matrix after polymerization. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

Poly(methyl methacrylate)/clay nanocomposites by photoinitiated free radical polymerization using intercalated monomer

A series of poly(methyl methacrylate)/montmorillonite (PMMA/MMT) nanocomposite were prepared by successfully dispersing the inorganic nanolayers of MMT clay in an organic PMMA matrix via in situ photoinitiated free radical polymerization. Methyl methacrylate monomer was first intercalated into the interlayer regions of organophilic clay hosts by “click” chemistry followed by a typical photoinitiated free radical polymerization. The intercalated monomer was characterized by FT-IR spectroscopy, elemental analysis and thermogravimetric analysis methods. The intercalation ability of the modified monomer and exfoliated nanocomposite structure were confirmed by X-ray diffraction spectroscopy (XRD), transmission electron microscopy (TEM) and atomic force microscopy (AFM). Thermal stability of PMMA/MMT nanocomposites was also studied by both differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).     

Synthesis of poly(vinyl acetate) containing diblock copolymer by DPE method

Diblock copolymer poly(methyl methacrylate)‐b‐poly(vinyl acetate) (PMMA‐b‐PVAc) was prepared by 1,1‐diphenylethene (DPE) method. First, free‐radical polymerization of methyl methacrylate was carried out with AIBN as initiator in the presence of DPE, giving a DPE containing PMMA precursor with controlled molecular weight. Second, vinyl acetate was polymerized in the presence of the PMMA precursor and AIBN, and PMMA‐b‐PVAc diblock copolymer with controlled molecular weight was obtained. The formation of PMMA‐b‐PVAc was confirmed by ¹H NMR spectrum. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) were used to detect the self‐assembly behavior of the diblock polymer in methanol. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Use of a new natural clay to produce poly(methyl methacrylate)‐based nanocomposites

Nanocomposites of poly(methyl methacrylate) (PMMA) filled with 3 wt% of modified natural Algerian clay (AC; montmorillonite type) were prepared by either in situ polymerization of methyl methacrylate initiated by 2,2′‐azobisisobutyronitrile or a melt‐mixing process with preformed PMMA via twin‐screw extrusion. The organo‐modification of the AC montmorillonite was achieved by ion exchange of Na⁺ with octadecyldimethylhydroxyethylammonium bromide. Up to now, this AC montmorillonite has found applications only in the petroleum industry as a rheological additive for drilling muds and in water purification processes; its use as reinforcement in polymer matrices has not been reported yet. The modified clay was characterized using X‐ray diffraction (XRD), which showed an important shift of the interlayer spacing after organo‐modification. The degree of dispersion of the clay in the polymer matrix and the resulting morphology of nanocomposites were evaluated using XRD and transmission electron microscopy. The resulting intercalated PMMA nanocomposites were analysed using thermogravimetric analysis and differential scanning calorimetry. The glass transition temperature of the nanocomposites was not significantly influenced by the presence of the modified clay while the thermal stability was considerably improved compared to unfilled PMMA. This Algerian natural montmorillonite can serve as reinforcing nanofiller for polymer matrices and is of real interest for the fabrication of nanocomposite materials with improved properties. Copyright © 2009 Society of Chemical Industry     

Synthesis of silica hybrid nanoparticles modified with photofunctional polymers and construction of colloidal crystals

Photofunctional polymer as silane coupling agent (PFD) was prepared by free radical copolymerization of 4‐vinylbenzyl N,N‐diethyldithiocarbamate (VBDC) and methyl methacrylate (MMA) in the presence of (3‐mercaptopropyl)trimethoxysilane (MPMS) as chain transfer agent. Next, silane (SiO₂; the average diameter D_n = 192 nm) nanoparticles was surface‐modified with PFD and 3‐(trimethoxysilyl)propyl methacrylate (γ‐MPS) by covalent bond formed between silanol groups and silane coupling agents. The PFD and γ‐MPS functionalizations changed the silica surface into hydrophobic nature and provided grafting initiation sites and methacrylate terminal groups respectively. We performed the construction of hybrid nanocomposites by using these modified SiO₂ nanoparticles. It was found from electron microscopy observations that SiO₂ particles were packed into repeating cubic arrangements in a poly(methyl methacrylate) (PMMA) matrix such as colloidal crystals. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

水性聚氨酯/聚甲基丙烯酸甲酯杂化乳液的合成

用异佛尔酮二异氰酸酯(IPDI)、聚丙二醇(PPG)和二羟甲丙酸(DMPA)合成了水性聚氨酯分散体(WPU),讨论了PPG摩尔质量,NCO/OH及PPG/DMPA比例对WPU乳液和涂膜性能的影响。以WPU为种子与甲基丙烯酸甲酯进行乳液聚合制备杂化乳液,研究了不同PU/PMMA物质的量比例对杂化乳液及涂膜性能的影响,并采用TEM对WPU及杂化乳液粒子进行了表征。结果表明,在以PPG1000为原料,NCO与OH物质的量比为1.4∶1,PPG与DMPA物质的量比为1∶0.8条件下制备的WPU杂化乳液,随着PMMA比例增加,杂化乳液的稳定性和成膜性变差,聚合物膜断裂伸长率降低,但铅笔硬度、耐水性及耐乙醇性均得到了改善。     

Atom transfer radical polymerization of methyl methacrylate induced by an initiator derived from an ionic liquid

An ionic liquid, 1‐(2‐bromoisobutyryloxyethyl)‐3‐methylimidazolium hexafluorophosphate, was synthesized to act as the initiator of the atom transfer radical polymerization of methyl methacrylate (MMA). By a combination with CuBr and pentamethyldiethylenetriamine, the ionic liquid initiated the free radical polymerization of MMA to proceed in a controlled way over a wide temperature range of 0 to 60 °C. The number‐average molecular weight of the poly(methyl methacrylate) (PMMA) increased with monomer conversion and the polydispersity was relatively narrow. End‐group analysis by proton NMR indicated the presence of the initiator fragments at the ends of the polymer main chain. Lowering the reaction temperature had the result of increasing the content of rr triads. The glass transition temperature was higher for PMMA obtained at lower temperature than at higher temperature. The solubility of the PMMA in methanol increased with the incorporation of imidazolium groups in the polymer. Copyright © 2006 Society of Chemical Industry     

Surface properties and chain structure of fluorinated acrylate copolymers prepared by emulsion polymerization

The fluorinated copolymer poly (MMA–co–FMA), composed of methyl methacrylate (MMA) and 2-perfluorooctylethyl methacrylate (FMA), was prepared by emulsion polymerization using a pre-emulsified monomer addition process. The results showed that the contact angle of water on its solvent-borne film increased dramatically and reached 118o when the FMA content in the copolymer was only 0.65 mol%, approaching that of poly(2-perfluorooctylethyl methacrylate) homopolymer. Unlike the copolymer prepared by solution polymerization, X-ray photoelectron spectroscopy (XPS), and sum frequency generation (SFG) vibrational spectroscopy analysis results indicated that the fluorinated moieties in this polymer were very easily segregated at the surface of the film. The interfacial structure and properties of this polymer in solution were investigated using SFG, surface tension, and dynamic laser light scattering (DLS). It was found that emulsion polymerization produced a chain structure of the fluorinated copolymer similar to that of FMA capped PMMA, thereby providing a possible way to produce fluorinated end-capped polymers using a popular polymerization method.     

Electrospun Polyvinyl Borate/Poly(Methyl Methacrylate) (PVB/PMMA) Blend Nanofibers

The aim of this study was to prepare polyvinyl borate (PVB)/poly(methyl methacrylate) (PMMA) blend nanofibers by electrospinning process. Polyvinyl borate was synthesized by the condensation reaction of polyvinyl alcohol and boric acid. FTIR analyses showed that boron atoms were found to be integrated into the polymer network. Blending PMMA with PVB decreased the fiber diameter and enhanced the surface roughness of PVB/PMMA blend nanofiber mats. The water wetting property of the nanofiber mats was influenced by the surface roughness. The blend composition with the highest polyvinyl borate content was found to be suitable for thermally stable nanofiber formation.     

Poly(methyl methacrylate)‐grafted cellulose nanocrystals: One‐step synthesis,nanocomposite preparation,and characterization

Cellulose nanocrystals (CNCs) are ideal reinforcing agents for polymer nanocomposites because they are lightweight and nano‐sized with a large aspect ratio and high elastic modulus. To overcome the poor compatibility of hydrophilic CNCs in non‐polar composite matrices, we grafted poly(methyl methacrylate) (PMMA) from the surface of CNCs using an aqueous, one‐pot, free radical polymerization method with ceric ammonium nitrate as the initiator. The hybrid nanoparticles were characterized by CP/MAS NMR, X‐ray photoelectron spectroscopy, infrared spectroscopy, contact angle, thermogravimetric analysis, X‐ray diffraction, and atomic force microscopy. Spectroscopy demonstrates that 0.11 g/g (11 wt %) PMMA is grafted from the CNC surface, giving PMMA‐g‐CNCs, which are similar in size and crystallinity to unmodified CNCs but have an onset of thermal degradation 45 °C lower. Nanocomposites were prepared by compounding unmodified CNCs and PMMA‐g‐CNCs (0.0025–0.02 g/g (0.25–2 wt %) loading) with PMMA using melt mixing and wet ball milling. CNCs improved the performance of melt‐mixed nanocomposites at 0.02 g/g (2 wt %) loading compared to the PMMA control, while lower loadings of CNCs and all loadings of PMMA‐g‐CNCs did not. The difference in Young's modulus between unmodified CNC and polymer‐grafted CNC composites was generally insignificant. Overall, ball‐milled composites had inferior mechanical and rheological properties compared to melt‐mixed composites. Scanning electron microscopy showed aggregation in the samples with CNCs, but more pronounced aggregation with PMMA‐g‐CNCs. Despite improving interfacial compatibility between the nanoparticles and the matrix, the effect of PMMA‐g‐CNC aggregation and decreased thermal stability dominated the composite performance.     

Preparation and physical properties of transparent organic–inorganic nanohybrid materials based on urethane dimethacrylate

The aim of this study was to prepare transparent organic–inorganic nanohybrid materials with improved physical properties in comparison with the matrix polymer. Polymerizable silica nanoparticles were synthesized via the reaction of silanol groups on the surface of silica nanoparticles (particle diameter ≈ 12 nm) with isocyanate groups of 2‐(methacryloyloxy)ethyl isocyanate (MOI) in ethyl acetate. In addition, the matrix monomer, urethane dimethacrylate, was prepared by the reaction of an MOI isocyanate group with the hydroxyl group of 2‐hydroxyethyl methacrylate, and novel organic–inorganic nanohybrid materials were obtained at various silica contents with bulk polymerization. The surface treatment of the silica nanoparticles and preparation of the matrix monomer were carried out in a one‐pot reaction. The prepared hybrid materials retained high transparency, and the elastic modulus and surface hardness improved with increasing silica content. Moreover, the strength of the material containing 20 wt % silica was up to 30 MPa higher than that of the matrix polymer. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

四官能度过氧化物JWEB50引发的PS-b-PMMA合成与表征

引言嵌段共聚物是具有两种或两种以上不同链段的聚合物,不同链段间存在的化学键限制了聚合物的相分离程度,易形成微相分离结构[1],而嵌段共聚物能作为聚合物共混体系的相容剂,只需加入少量