Five types of modification reactions were used to introduce PE chains onto the surface of nano SiO2 and reactive nano SiO2, where silanol groups were chlorinated using tetrachlorosilane (SiCl4). The results show that the reaction between Si–Cl and the epoxy group is more active than the others, and the highest grafting ratio is up to 41.4% deduced from the thermogravimetric analysis (TGA). The result of TEM and SEM indicate that the PE-modified SiO2 particles are uniformly dispersed, and the SiO2 particle size is approximately 100–300 nm. The shear rheology results reveal that the PE chains covalently attached on the surface of the nanosilica have strong interaction with the PE matrix and enhance the melt strength of LDPE. The thermal properties of LDPE/SiO2 nanocomposites almost remain unchanged via TGA and differential scanning calorimetry (DSC) experiments.

The polypropylene-graft-polyisoprene (PP-g-PIP) copolymers with different side chain length were synthesized by the combination of solid phase graft and anionic polymerization. The copolymers were characterized by nuclear magnetic resonance spectrum (1H-NMR), gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). Five PP/PP-g-PIP blends with PP-g-PIP as a flexibilizer to toughen PP were prepared and characterized by scanning electron microscope (SEM), dynamic mechanical analysis (DMA), DSC, wide-angle X-ray diffraction (WAXD). Their morphologies, glass transition temperatures, crystallinity and mechanical properties were investigated. All the results pointed out that the covalent bonding of PP and PIP increased the compatibility and interfacial adhesion, which led to PIP well dispersed in the system and small size PIP particles in the binary blends. In addition, the toughness of PP was improved while its tensile strength slightly decreased.

Layered materials (MMT, LDH) were successfully modified by chain end functionalized polyethylene via an ion exchange method. The samples were characterized by using elemental analysis, Fourier transform infrared (FTIR) spectrum, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The XRD results demonstrated that MMT was successfully exfoliated with the disappearance of [001] peak. For the LDH, the peak [003] moved to a low angle and greatly weakened, indicating that LDH was successfully functionalized and completely intercalated or exfoliated. HDPE/layered nanocomposites were obtained between HDPE and different content of functional layered materials. The SEM and TEM results of nanocomposites showed the layered materials were well dispersed in the HDPE matrix, with a particle size of 100−200 nm.

Carbon nanoforms (CNFs, including graphene, carbon nanotube and fullerene) were functionalized via microwave-assisted thiol-ene click chemistry. Different functional CNFs with −COOH, −NH2, −NH3Cl,-Si(OCH3)3, alkyl and furyl groups were obtained and characterized by XPS, EDS, TGA, Raman spectroscopy and MALDI-TOF MS. Microwave was much more efficient to promote reactions than traditional thermal method. XPS confirmed the binding energy of C-S-C (163.3ev) the modified CNFs. Raman spectroscopy showed increasing ID/IG and AD/AG of graphene and CNT after thiol-ene addition reaction. The result of MALDI-TOF MS indicated that the thiol-containing molecules were attached on fullerene. All these results indicated the successful thiol-ene click reactions between CNFs and thiol-containing molecules under microwave. TGA analysis results showed the mass loss of the modified CNFs, which provided that AIBN and 3-merlaptopropionic acid were the most efficient initiator and monomer, respectively. In summary, the microwave-assisted thiol-ene click reaction provided a powerful chemical tool for the preparation of functional CNFs materials.Carbon nanoforms (CNFs, fullerenes, nanotubes, and graphene) have played important roles in the fields of material science and nanocomposite. We provided a novel strategy to obtain functional CNFs via microwave-assisted thiol-ene click chemistry.Download high-res image (151KB)Download full-size image

•A new hyperbranched multi-arm star polymer was successfully synthesized.•The star polymer electrolyte has good thermal stability and forming-film property.•The ion conductivity electrolyte can reach 8.3 × 10−5 S cm−1 at room temperature.•The star polymer electrolyte has wide electrochemical windows of 4.7 V.A new hyperbranched multi-arm star polymer with hyperbranched polystyrene (HBPS) as core and polymethyl methacrylate-block-poly(ethylene glycol) methyl ether methacrylate(PMMA-b-PPEGMA) as arms was firstly synthesized by atom transfer radical polymerization. The obtained hyperbranched multi-arm star polymer (HBPS-(PMMA-b-PPEGMA)x) exhibited good thermal stability with a thermal decomposition temperature of 372 °C. The transparent, free-standing, flexible polymer electrolyte film of the blending of HBPS-(PMMA-b-PPEGMA)x and lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) was successfully fabricated by a solution casting method. The ionic conductivity of the hyperbranched star polymer electrolyte with a molar ratio of [EO]/[Li] of 30 could reach 8.3 × 10−5 S cm−1 at 30 °C (with the content of PPEGMA of 83.7%), and 2.0 × 10−4 S cm−1 at 80 °C (with the content of PPEGMA of 51.6%). The effect of the concentration of lithium salts on ionic conductivity was also investigated. The obtained all-solid-state polymer electrolyte possessed a wide electrochemical stability window of 4.7 V (vs. Li+/Li), and a lithium-ion transference number (tLi+) up to 0.31. The interfacial impedance of the fabricated Li│polymer electrolyte│Li symmetric cell based on hyperbranched star multi-arm polymer electrolyte exhibited good interfacial compatibility between all-solid-state polymer electrolyte and electrodes. The excellent properties of the hyperbranched star polymer electrolyte made it attractive as solid-state polymer electrolyte for lithium-ion batteries.

A novel type of spherical nano Ziegler–Natta catalyst was prepared by loading TiCl4 on nanosized magnesium chloride support for propylene polymerization to form nanosized spherical polypropylene (PP) particles. Polyvinylpyrrolidone (PVP), a common macromolecular surfactant, was used to ensure sphericity and inhibit aggregation of the nanosized particles. The morphology of the support (60 nm), catalyst (80 nm), and PP particles (500 nm) were spherical, and the size distribution is uniform which is confirmed by scanning electron microscopy (SEM) and transmission electron microscope (TEM), respectively. The laser granulometer results showed that the size of the prepared PP particles was in the range of 10–110 um, and the average diameter was 36 um, which had potential application in 3D printing. In addition, the obtained polypropylene had low bulk density (0.170 g/mL).

Hyperbranched poly(glycidol) containing hydroxyl groups was firstly synthesized via anionic polymerization and then reacted with 2-bromoisobutyl bromide to form macroinitiator HPG-Br. Finally, a hyperbranched star polymer (HPG-PPEGMA) was successfully prepared by atom transfer radical polymerization (ATRP) of poly(ethylene glycol) methyl ether methacrylate using HPG-Br as macroinitiator. The structures and properties of the obtained polymers were characterized by 1H NMR, attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The ionic conductivity of the polymer electrolytes composed of HPG-PPEGMA and lithium bis(trifluoromethanesulfonimide) (LiTFSI) was investigated via electrochemical impedance spectroscopy. The results showed that the room temperature ionic conductivity of the prepared hyperbranched star polymer electrolytes had a higher ionic conductivity. When [EO]/[Li] was 20, the ionic conductivity of the hyperbranched star polymer electrolyte was up to 1 × 10−4 Scm−1 at 30 °C. The onset decomposition temperature of the hyperbranched star polyether could reach 374 °C, indicating that the hyperbranched star polymer had a good thermal stability. The XRD results showed that the structure of the hyperbranched star polymer was beneficial to improve the ionic conductivity due to possessing a low degree of crystallinity.

Low dispersity star-like polyethylene with a “silica” core was synthesized via a simple yet efficient sol–gel process using trimethoxysilane-terminated polyethylene, which was prepared using radical-mediated thiol-ene click chemistry between low molecular weight vinyl-terminated polyethylene and (3-mercaptopropyl)trimethoxysilane.

A wide range of low-molecular-weight, narrow-molecular-weight-distribution chain end functionalized polyethylenes (Cef-PEs), including hydroxyl-, amino-, carboxyl-, sulfo-, chloro-, azide- and trimethoxysilane-terminated polyethylenes, were synthesized under mild conditions via epoxide ring-opening and thiol–ene addition reactions with epoxy- and vinyl-terminated PEs as starting materials, respectively. The selectivities of the functionalizations were excellent. Similarly, amphiphilic polyethylene-block-poly(ethylene glycol) copolymer (PE-b-PEG) was prepared for the first time by simply treating epoxy terminated PE with hydroxyl terminated PEG and potassium hydroxide. A unique combination of primary (hindered-phenol) and secondary (thioester) antioxidants was introduced into the chain end of PE via successive thiol–ene addition and transesterification reactions. All Cef-PEs were characterized unambiguously by NMR, GPC, DSC and FTIR.

Five new alkoxysilanes with different sizes of hydrocarbon substituents were first synthesized and employed as external donors for propylene polymerization with a Ziegler–Natta catalyst. The effects of these and industrial alkoxysilanes with different sizes of hydrocarbon substituents on the microstructure of polypropylene were studied by SSA and 13C NMR. The results showed that isotactic sequence length of polypropylene increased with the size of R2 substituent on alkoxysilanes in the five donor systems, similar to the regularity of molecular weight, isotacticity, and thermal properties of polypropylene. Although the polypropylene produced by double cycloalkane substituents on alkoxysilanes had lower lamellae thickness L1, its contents were the highest. Moreover, excess large volume of hydrocarbon substituents on alkoxysilanes might be detrimental to improving isotactic sequence length of polypropylene. Polypropylene prepared by MIPDMS had a more uniform distribution of the stereodefects, indicating that MIPDMS might be used for the industrial production of BOPP.

The new aminosilane compounds including Dimorpholindimethoxysilane (Donor-Pm), Di (1-methylpiperazine) dimethoxysilane (Donor-Pz) and Di (isopropylpiperazine) dimethoxysilane (Donor-Pi) were firstly synthesized and then employed as external donors for propylene polymerization with MgCl2-supported Ziegler-Natta catalyst, compared with dipiperidine dimethoxysilane (Donor-Py). The effects of the aminosilane external donors on the catalytic activity, hydrogen response, and molecular weight distribution, crystalline ability, thermal property, isotactic sequence length, isotactic sequence distribution of polypropylene were studied by differential scanning calorimetry (DSC), gel permeation chromatography (GPC), and self-nucleation and annealing (SSA), respectively. It was found that these new aminosilane compounds were conducive to improving the isotacticity of polypropylene and the catalytic activity. The GPC results showed that the molecular weight distribution of polypropylene prepared respectively by Donor-Pz or Donor-Pi with two N atoms on each amino substituent group was broader more than 8.0, especially for Donor-Pi with the large alkyl-substituted group on each nitrogen atom, the molecular weight distribution of polypropylene was about 11.2, which was much broader than that of industrial polypropylene about 4 ~ 5. The DSC results indicated that the degrees of crystallinity of polypropylene prepared by the aminosilane external donors were higher, and the crystallization ability of polypropylene prepared by Donor-Pi was lower but closed to that of polypropylene prepared by Donor-Py. The SSA results indicated Donor-Py and Donor-Pi were conducive to improving the relative contents of the highest isotactic component of polypropylene, and the lamellae thicknesses results showed the sequence length of polypropylene prepared by Donor-Py and Donor-Pi were longer, and the isotactic sequence distribution of polypropylene prepared by Donor-Py and Donor-Pi were broader. The study results showed that the new aminosilane donor Donor-Pi was conducive to improving the stereo-regularity of polypropylene, especially revealing that it was a simple and an effective method to synthesize broad molecular weight distribution of polypropylene by using appropriate aminosilane external donor for propylene polymerization.

•A series of novel copolymers were synthesized via cationic polymerization.•The ionic conductivity of polymer electrolytes has large improvement.•These polymers and PEO matrix have good compatibility.•The good compatibility can evidently promote ion migration.A series of novel branched copolyethers, poly((1,3-dioxlolane)-co-((2-(2-methoxylethoxyl)methyl)oxirane)) (P(DXL-co-MEMO)) and poly((1,3-dioxlolane)-co-((2-(2-(2-methoxylethoxyl)ethoxyl)methyl)oxirane)) (P(DXL-co-ME2MO)), were synthesized via cationic polymerization, and the structures of these copolymers were characterized by 1H NMR and GPC. Ionic conductivities of copolyether/lithium bis(trifluoromethanesulphonyl)imide (LiTFSI), polyethylene oxide (PEO)/LiTFSI and PEO/copolyether/LiTFSI were investigated via electrochemical impedance spectroscopy. The results showed that the ionic conductivity of the P(DXL-co-MEMO)/LiTFSI polymer electrolyte was higher than that of the P(DXL-co-ME2MO)/LiTFSI polymer electrolyte, and the room temperature ionic conductivity of the P(DXL-co-MEMO)/LiTFSI polymer electrolyte was up to 2.2 × 10− 4 S cm− 1. Compared with the PEO/LiTFSI polymer electrolyte, the ionic conductivities of the PEO/copolyether/LiTFSI composite polymer electrolytes had a great improvement, but their thermal stabilities did not obviously reduce.

Hyperbranched star polymer HBPS-(PPEGMA)x was synthesized by atom transfer radical polymerization (ATRP) using hyperbranched polystyrene (HBPS) as macroinitiator and poly(ethylene glycol) methyl ether methacrylate (PEGMA) as monomer. The structure of the prepared hyperbranched star polymer was characterized by 1H NMR, ATR-FTIR, and GPC. Polymer electrolytes based on HBPS-(PPEGMA)x, lithium salt, and/or nano-TiO2 were prepared. The influences of lithium salt concentration and type, nano-TiO2 content, and size on ionic conductivity of the obtained polymer electrolytes were investigated. The results showed that the low crystallinity of the prepared polymer electrolyte was caused by the interaction between lithium salt and polymer. The addition of TiO2 into HBPS-(PPEGMA)x/LiTFSI improved the ionic conductivity at low temperature. The prepared composite polymer electrolyte showed the highest ionic conductivity of 9 × 10−5 S cm−1 at 30 °C when the content of TiO2 was 15 wt% and the size of TiO2 was 20 nm.

Polypropylene samples with fullerene C60, fullerenol C60(OH)24, 1010, C60/168, C60-OH/168 and 1010/168 as antioxidants were prepared by extrusions. MFR, YI, TGA and OIT of all the samples were tested. According to the results of MFR, during the melt extrusion, fullerene showed excellent stability effect on PP. The antioxidative ability of fullerene was comparable to the traditional antioxidant 1010. The antioxidative ability of fullerenol was not significant in the first extrusion and it accelerated the degradation of PP in the second and the third extrusions. TGA and OIT tests showed that the stability effects of fullerene and fullerenol were slightly lower than antioxidant 1010. In the first time, antioxidant 168 was reported to show great synergistic effects with fullerene and fullerenol as antioxidants, which sussested a simple way to enhance the antioxidative abilities of fullerene and fullerenol.

Four new diester compounds were prepared and used as internal donors (ID) to prepare MgCl2 supported titanium catalysts. Different diesters had notable influences on the porosity and the specific surface areas of the catalysts. The propylene polymerizations results showed that isopropyl groups(ID-2), cyclopentyl(ID-4) were more suitable substituents for diester compounds to replace phenyl(DIBP). The effects of different external donor (ED), Si/Ti ratio and hydrogen response on new ID precatalysts were evaluated by propylene polymerization.

Hyperbranched poly(glycidol) (HPG) containing hydroxyl groups is firstly synthesized via anionic polymerization, and then reacts with thionyl chloride to form chlorine end-terminated hyperbranched poly(glycidol) (HPG-Cl). Different ionic liquid polymers are synthesized from the reaction of HPG-Cl with N-methylimidazole and then anion exchange with hexafluorophosphoric acid and sodium tetrafluoroborate. The structure and properties of the obtained ionic liquid polymers are characterized by 1H NMR, ATR-FTIR, DSC and TGA, respectively. Ionic conductivity of the polymer electrolytes composed of ionic liquid polymer and lithium bis(trifluoromethanesulfonimide) (LITFSI) is investigated by electrochemical impedance spectroscopy. The results show that the ionic conductivity of the prepared ionic liquid polymer electrolyte can reach 3.5 × 10−4 Scm−1 at 30 °C when the weight ratio of ionic liquid polymer ([HPG-MeIm]BF4) to lithium salt (LiTFSI) is 4.5.

As the external donor in Ziegler-Natta catalysts have an important influence on the stereo-defects distribution of polypropylene, the effects of the mixed external donors (the mixture of Donor-C (cyclohexylmethyldimethoxysilane) and Donor-N (n-propyltriethoxysilane) ) on the isotactic sequence length and its distribution of polypropylene prepared by Ziegler-Natta catalyst through propylene bulk polymerization were studied through the Successive self-nucleating and annealing (SSA) and 13C-NMR techniques. The SSA results showed that the relative contents of the highest isotactic component and the lamellar thickness in the polypropylene chain gradually increased with the increase of the relative component of Donor-C in the C/N mixed external donors, indicating the isotactic sequence length of polypropylene got longer, and the lamellar thickness distribution of polypropylene became broader, revealing the isotactic sequence length distribution of polypropylene got broader. In addition, the 13C-NMR results showed that the average meso isotactic sequence length (MSL) of polypropylene gradually increased with the increase of the content of Donor-C in the C/N mixed external donors, which was in good coincident with the results calculated from SSA, showing a good correspondence between the SSA and 13C-NMR techniques.

The effect of successive self-nucleation and annealing (SSA) parameters including the annealing time ts, annealing temperature interval and heating and cooling rates on the crystallization properties of polypropylene were researched in detail. Based on those results, the crystallization behavior and the sequence length distribution of polypropylene with different isotacticity and propylene/1-butene copolymer with different 1-butene comonomer content prepared by Ziegler–Natta catalyst were studied through SSA. With the increase of the isotacticity of polypropylene, the sequence length of the polypropylene gradually increases. The polypropylene prepared by propylene bulk polymerization has stronger crystallization ability and longer sequence length than that prepared by propylene sully polymerization. For the propylene/1-butene copolymer, the crystallization ability gradually reduces and the sequence length of each chain segment gradually decreases with the increase of 1-butene content in copolymer. In addition, the polypropylene samples with similar isotactic index prepared by Ziegler–Natta catalyst and metallocene catalyst under similar polymerization condition were also characterized through the SSA technique. The results show that the sequence length of polypropylene prepared by Ziegler–Natta catalyst is far longer than that prepared by metallocene catalyst. The interesting phenomenon that polypropylene prepared by metallocene catalyst has multiple melting peaks after SSA treatment, which is similar to the polypropylene prepared by Ziegler–Natta catalyst, was first reported.

This paper reports the synthesis and characterization of four neutral chromium(III) complexes bearing N,O,N′-tridentate ligands, [LCrCl3], (L = 2-[(2-pyridylmethoxy)methyl]pyridine, 1; L = 8-(2-pyridylmethoxy)quinoline, 2; L = 8-[(2-pyridylmethoxy)methyl]quinoline, 3; L = 8-(quinolin-8-ylmethoxy)quinoline, 4). Molecular structures of 1–3 have been determined by X-ray crystallography, which show that L1 and L3 exhibit facial configuration in 1 and 3 while L2 adopts meridional arrangement in 2. The ethylene polymerization experiments show that complexes 1–4 are moderately active precatalysts for ethylene polymerization with activation with MAO.Graphical abstractFour neutral chromium(III) complexes bearing N,O,N′-tridentate ligands have been synthesized and characterized. Three molecular structures have been determined by X-ray crystallography, which show that two molecular structures exhibit facial configuration while the other adopts meridional arrangement. The ethylene polymerization experiments show that four complexes are moderately active precatalysts for ethylene polymerization with activation with MAO.Highlights► Four chromium(III) complexes with N,O,N′-tridentate ligands were synthesized. ► Molecular structures of three complexes were determined by X-ray crystallography. ► These complexes were found to be moderately active precatalysts for ethylene polymerization.