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2011 Volume 29 Issue 5
2011, 29(5): 520-531
doi: 10.1007/s10118-011-1067-1
Abstract:
The effect of channel-protein interaction on the translocation of a protein-like chain through a finite channel under certain electric field was studied by using dynamical Monte Carlo simulations. The interior behavior of chain conformation under different interactions was investigated, such as the number of monomers outside of channel nout, monomers inside of channel nm, mean-square radius of gyration S2 and the average energy U. It shows that with strong attractive interaction, the translocation is more difficult than moderate interaction. At the same time，the dependence of translocation time with different interactions shows that moderate repulsive interaction (cp = 0.5) accelerates the translocation. Although the waiting time for successful translocation of cp = 1.0 is the longest, the average translocation time is not very large. It is far smaller than that of cp = -1.0. The probability distributions of translocation time p(t') and the probability distributions of three duration times p(t1'), p(t2') and p(t3') were all discussed. Log-normal distributions are found. All these findings will strengthen the understanding of protein translocation.
The effect of channel-protein interaction on the translocation of a protein-like chain through a finite channel under certain electric field was studied by using dynamical Monte Carlo simulations. The interior behavior of chain conformation under different interactions was investigated, such as the number of monomers outside of channel nout, monomers inside of channel nm, mean-square radius of gyration S2 and the average energy U. It shows that with strong attractive interaction, the translocation is more difficult than moderate interaction. At the same time，the dependence of translocation time with different interactions shows that moderate repulsive interaction (cp = 0.5) accelerates the translocation. Although the waiting time for successful translocation of cp = 1.0 is the longest, the average translocation time is not very large. It is far smaller than that of cp = -1.0. The probability distributions of translocation time p(t') and the probability distributions of three duration times p(t1'), p(t2') and p(t3') were all discussed. Log-normal distributions are found. All these findings will strengthen the understanding of protein translocation.
2011, 29(5): 532-539
doi: 10.1007/s10118-011-1063-5
Abstract:
A series of sulfonated polyimides (SPIs) containing pyridine groups were prepared by direct polycondensation from 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA), 4,4'-diaminodiphenyl ether-2,2'-disulfonic acid (ODADS) and 4-(4-methoxy)phenyl-2,6-bis(4-aminophenyl)pyridine (DAM). The resulting copolymers displayed good solubility in common organic solvents. Flexible, transparent, tough membranes were obtained via solution casting. All the films showed high thermal stability with desulfonation temperature over 300C. They exhibited prominent mechanical properties with Youngs modulus around 2.0 GPa. High proton conductivity (0.23 S/cm at 100% RH) was also observed. More importantly, the new materials exhibited low water uptake (30 wt%-75 wt% at 80C) and improved water stability, which were attributed to the acid-base interaction between sulfonic acid and pyridine functional groups.
A series of sulfonated polyimides (SPIs) containing pyridine groups were prepared by direct polycondensation from 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA), 4,4'-diaminodiphenyl ether-2,2'-disulfonic acid (ODADS) and 4-(4-methoxy)phenyl-2,6-bis(4-aminophenyl)pyridine (DAM). The resulting copolymers displayed good solubility in common organic solvents. Flexible, transparent, tough membranes were obtained via solution casting. All the films showed high thermal stability with desulfonation temperature over 300C. They exhibited prominent mechanical properties with Youngs modulus around 2.0 GPa. High proton conductivity (0.23 S/cm at 100% RH) was also observed. More importantly, the new materials exhibited low water uptake (30 wt%-75 wt% at 80C) and improved water stability, which were attributed to the acid-base interaction between sulfonic acid and pyridine functional groups.
2011, 29(5): 540-551
doi: 10.1007/s10118-011-1066-2
Abstract:
One-step reaction compatibilized microfibrillar reinforced iPP/PET blends (CMRB) were successfully prepared through a slit extrusion-hot stretching-quenching process. Crystallization behavior and morphology of CMRB were systematically investigated. Scanning electronic microscopy (SEM) observations showed blurry interface of compatibilized common blend (CCB). The crystallization behavior of neat iPP, CCB, microfibrillar reinforced iPP/PET blend (MRB) and CMRB was investigated by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The increase of crystallization temperature and crystallization rate during nonisothermal crystallization process indicated both PET particles and microfibrils could serve as nucleating agents and PET microfibrils exhibited higher heterogeneous nucleation ability, which were also vividly revealed by results of POM. Compared with MRB sample, CMRB sample has lower crystallization temperature due to existence of PET microfibrils with smaller aspect ratio and wider distribution. In addition, since in situ compatibilizer tends to stay in the interphase, it could also hinder the diffusion of iPP molecules to the surface of PET phase, leading to decrease of crystallization rate. Two-dimensional wide-angle X-ray diffraction (2D-WAXD) was preformed to characterize the crystalline structure of the samples by injection molding, and it was found that well-developed PET microfibrils contained in MRB sample promoted formation of -phase of iPP.
One-step reaction compatibilized microfibrillar reinforced iPP/PET blends (CMRB) were successfully prepared through a slit extrusion-hot stretching-quenching process. Crystallization behavior and morphology of CMRB were systematically investigated. Scanning electronic microscopy (SEM) observations showed blurry interface of compatibilized common blend (CCB). The crystallization behavior of neat iPP, CCB, microfibrillar reinforced iPP/PET blend (MRB) and CMRB was investigated by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The increase of crystallization temperature and crystallization rate during nonisothermal crystallization process indicated both PET particles and microfibrils could serve as nucleating agents and PET microfibrils exhibited higher heterogeneous nucleation ability, which were also vividly revealed by results of POM. Compared with MRB sample, CMRB sample has lower crystallization temperature due to existence of PET microfibrils with smaller aspect ratio and wider distribution. In addition, since in situ compatibilizer tends to stay in the interphase, it could also hinder the diffusion of iPP molecules to the surface of PET phase, leading to decrease of crystallization rate. Two-dimensional wide-angle X-ray diffraction (2D-WAXD) was preformed to characterize the crystalline structure of the samples by injection molding, and it was found that well-developed PET microfibrils contained in MRB sample promoted formation of -phase of iPP.
2011, 29(5): 552-559
doi: 10.1007/s10118-011-1078-y
Abstract:
Using supported multi-component zinc dicarboxylate catalyst, poly(1,2-propylene carbonate-co-1,2-cyclohexylene carbonate) (PPCHC) was successfully synthesized from carbon dioxide (CO2) with propylene oxide (PO) and cyclohexene oxide (CHO). The conversion of epoxides dramatically increased up to 89.7% (yield: 384.2 g of polymer per g of Zn) with increasing reaction temperature from 60C to 80C. The optimized reaction temperature is 80C. The chemical structure, the molecular weight, as well as thermal and mechanical properties of the resulting terpolymers were investigated extensively. When CHO feed content (mol%) is lower than 10%, the PPCHC terpolymers have number average molecular weight (Mn) ranging from 102 103 to 202 103 and molecular weight distribution (MWD) values ranging from 2.8 to 3.5. In contrast to poly(propylene carbonate) (PPC), the introduction of small amount of CHO leads to increase in the glass transition temperature from 38.0C to 42.6C. Similarly, the mechanical strength of the synthesized terpolymer is greatly enhanced due to the incorporation of CHO. These improvements in mechanical and thermal properties are of importance for the practical application of PPC.
Using supported multi-component zinc dicarboxylate catalyst, poly(1,2-propylene carbonate-co-1,2-cyclohexylene carbonate) (PPCHC) was successfully synthesized from carbon dioxide (CO2) with propylene oxide (PO) and cyclohexene oxide (CHO). The conversion of epoxides dramatically increased up to 89.7% (yield: 384.2 g of polymer per g of Zn) with increasing reaction temperature from 60C to 80C. The optimized reaction temperature is 80C. The chemical structure, the molecular weight, as well as thermal and mechanical properties of the resulting terpolymers were investigated extensively. When CHO feed content (mol%) is lower than 10%, the PPCHC terpolymers have number average molecular weight (Mn) ranging from 102 103 to 202 103 and molecular weight distribution (MWD) values ranging from 2.8 to 3.5. In contrast to poly(propylene carbonate) (PPC), the introduction of small amount of CHO leads to increase in the glass transition temperature from 38.0C to 42.6C. Similarly, the mechanical strength of the synthesized terpolymer is greatly enhanced due to the incorporation of CHO. These improvements in mechanical and thermal properties are of importance for the practical application of PPC.
2011, 29(5): 560-568
doi: 10.1007/s10118-011-1069-z
Abstract:
The polymerization of 1-octene initiated by methylalumoxane (MAO)-activated Ni(II)-based--diimine complexes [(2,6-i-Pr)2C6H3-DAB(An)]NiBr2 was investigated. Using this catalyst, poly(1-octene)s with molecular weight between 100 103 and 400 103 and polydispersity (Mw/Mn) between 1.3 and 1.5 were synthesized successfully by varying reaction time at room temperature. The poly(1-octene)s were amorphous polymers and could be well soluble in tetrahydrofuran (THF). After fractional precipitation, poly(1-octene)s with narrow molecular weight distributions (Mw/Mn 1.12) were obtained. Their weight-average molecular weights were measured by gel permeation chromatography (GPC) in conjunction with online model BI-MwA multiangle laser light scattering (MALLS), and their intrinsic viscosities were measured by Marons single-point method. The k and values in Mark-Houwink equation [] = KM in THF at 40℃ were 0.089 mL/g and 0.61 respectively.
The polymerization of 1-octene initiated by methylalumoxane (MAO)-activated Ni(II)-based--diimine complexes [(2,6-i-Pr)2C6H3-DAB(An)]NiBr2 was investigated. Using this catalyst, poly(1-octene)s with molecular weight between 100 103 and 400 103 and polydispersity (Mw/Mn) between 1.3 and 1.5 were synthesized successfully by varying reaction time at room temperature. The poly(1-octene)s were amorphous polymers and could be well soluble in tetrahydrofuran (THF). After fractional precipitation, poly(1-octene)s with narrow molecular weight distributions (Mw/Mn 1.12) were obtained. Their weight-average molecular weights were measured by gel permeation chromatography (GPC) in conjunction with online model BI-MwA multiangle laser light scattering (MALLS), and their intrinsic viscosities were measured by Marons single-point method. The k and values in Mark-Houwink equation [] = KM in THF at 40℃ were 0.089 mL/g and 0.61 respectively.
2011, 29(5): 569-574
doi: 10.1007/s10118-011-1064-4
Abstract:
The analytical expressions of the various structural units and the average degree of branching for the hyperbranched polymers resulted from AB2 polycondensation with substitution effect were derived by the kinetic mechanism. The reactivity difference between the B group in linear unit and that in terminal group has great effect on the molecular parameters of the products obtained. The concentration of terminal units has a maximum with the increase of the conversion of A groups (x). The higher the reactivity ratio (r) of linear B group to branched one is, the later the maximum appears and the larger it is. The degree of branching of the hyperbranched polymers obtained is controllable by adjusting the parameters of r and x, which increases with increasing both x and r.
The analytical expressions of the various structural units and the average degree of branching for the hyperbranched polymers resulted from AB2 polycondensation with substitution effect were derived by the kinetic mechanism. The reactivity difference between the B group in linear unit and that in terminal group has great effect on the molecular parameters of the products obtained. The concentration of terminal units has a maximum with the increase of the conversion of A groups (x). The higher the reactivity ratio (r) of linear B group to branched one is, the later the maximum appears and the larger it is. The degree of branching of the hyperbranched polymers obtained is controllable by adjusting the parameters of r and x, which increases with increasing both x and r.
2011, 29(5): 575-579
doi: 10.1007/s10118-011-1065-3
Abstract:
The chemical grafting of thiol terminated poly(sodium styrenesulfonate) (HS-PSSS) chains from sodium nitrate (NaNO3) salt solution to a gold surface was investigated with a quartz crystal microbalance with dissipation monitoring (QCM-D) in different salt concentrations. It was found that at low salt concentration grafting density of HS-PSSS was low and the grafted chains adopted a mushroom conformation. With the increase of salt concentration polyelectrolyte chains underwent a transition toward coiled state due to reduction of electrostatic repulsion and as a result more chains were grafted on the surface. When the grafting density reached a certain limit after which further grafting caused repulsion between already grafted HS-PSSS chains and as a result grafted chains adopted a brush conformation.
The chemical grafting of thiol terminated poly(sodium styrenesulfonate) (HS-PSSS) chains from sodium nitrate (NaNO3) salt solution to a gold surface was investigated with a quartz crystal microbalance with dissipation monitoring (QCM-D) in different salt concentrations. It was found that at low salt concentration grafting density of HS-PSSS was low and the grafted chains adopted a mushroom conformation. With the increase of salt concentration polyelectrolyte chains underwent a transition toward coiled state due to reduction of electrostatic repulsion and as a result more chains were grafted on the surface. When the grafting density reached a certain limit after which further grafting caused repulsion between already grafted HS-PSSS chains and as a result grafted chains adopted a brush conformation.
2011, 29(5): 580-585
doi: 10.1007/s10118-011-1061-7
Abstract:
A novel method for preparation of polymer-based magnetic microspheres was proposed by utilizing melt reactive blending, which was based on selective location of Fe3O4 nanoparticles in PA6 domains of polystyrene (PS)/polyamide 6 (PA6) immiscible blends. The morphology of PA6/Fe3O4 composite magnetic microspheres was studied by scanning electronic microscopy (SEM). The composite magnetic microspheres were spherical with a diameter range of 0.5-8 m; the diameter was sharply decreased with a very narrow distribution by adding terminal maleic anhydride functionalized polystyrenes (FPS) for reactive blending. Transmission electron microscopy (TEM) and thermogravimetry analysis (TGA) results showed that most of Fe3O4 was located in the PA6 microspheres. Magnetization data revealed the magnetite content of PA6/Fe3O4 microspheres was about 32 wt% and the saturation magnetization could be up to 17.2 Am2/kg.
A novel method for preparation of polymer-based magnetic microspheres was proposed by utilizing melt reactive blending, which was based on selective location of Fe3O4 nanoparticles in PA6 domains of polystyrene (PS)/polyamide 6 (PA6) immiscible blends. The morphology of PA6/Fe3O4 composite magnetic microspheres was studied by scanning electronic microscopy (SEM). The composite magnetic microspheres were spherical with a diameter range of 0.5-8 m; the diameter was sharply decreased with a very narrow distribution by adding terminal maleic anhydride functionalized polystyrenes (FPS) for reactive blending. Transmission electron microscopy (TEM) and thermogravimetry analysis (TGA) results showed that most of Fe3O4 was located in the PA6 microspheres. Magnetization data revealed the magnetite content of PA6/Fe3O4 microspheres was about 32 wt% and the saturation magnetization could be up to 17.2 Am2/kg.
2011, 29(5): 586-596
doi: 10.1007/s10118-011-1075-1
Abstract:
Electrical conduction behavior of pristine and iodine doped polyetherimides (PEI) has been investigated under both transient and steady state conditions in the operating temperature range 50-200C at various electric fields of 12-60 kV/cm. The transient currents show the hyperbolic decay character, and the decay exponent p (a measure of current decay rate) decreases with temperature (T) and doping concentration. The origin of transient currents has been attributed to the dipolar nature of carbonyl (＝C＝O) groups and the ether linkages present in the main chain of PEI. The low field steady state conduction is ohmic in nature. The magnitudes of ionic jump distance (a) values do not favor an ionic type of conduction as a possible conduction mechanism in pristine as well as iodine doped PEI. The Schottky coefficients estimations do not show the possibility of Schottky type or Poole-Frenkel type conduction mechanisms in the low temperature region ( 120C), however, in the high temperature region ( 120C) there is a certain possibility of Poole-Frenkel type conduction mechanism in both pristine and iodine doped samples. The dual slope in the lgI versus 1/T curves for iodine doped samples indicates the presence of more than one type of trapping levels.
Electrical conduction behavior of pristine and iodine doped polyetherimides (PEI) has been investigated under both transient and steady state conditions in the operating temperature range 50-200C at various electric fields of 12-60 kV/cm. The transient currents show the hyperbolic decay character, and the decay exponent p (a measure of current decay rate) decreases with temperature (T) and doping concentration. The origin of transient currents has been attributed to the dipolar nature of carbonyl (＝C＝O) groups and the ether linkages present in the main chain of PEI. The low field steady state conduction is ohmic in nature. The magnitudes of ionic jump distance (a) values do not favor an ionic type of conduction as a possible conduction mechanism in pristine as well as iodine doped PEI. The Schottky coefficients estimations do not show the possibility of Schottky type or Poole-Frenkel type conduction mechanisms in the low temperature region ( 120C), however, in the high temperature region ( 120C) there is a certain possibility of Poole-Frenkel type conduction mechanism in both pristine and iodine doped samples. The dual slope in the lgI versus 1/T curves for iodine doped samples indicates the presence of more than one type of trapping levels.
2011, 29(5): 597-601
doi: 10.1007/s10118-011-1070-6
Abstract:
TiCl4/MgCl2/clay compound catalyst was prepared by chemical reaction. Exfoliated polypropylene (PP)/clay nanocomposites were synthesized by in situ polymerization with this compound catalyst. Effects of polymerization temperature, polymerization time, propylene pressure, solvent consumption and pre-treat time of catalyst on catalyst activity and catalytic stereospecificity were studied. Under optimal conditions, activity of the nano-compound catalyst is about 88.3 kg/(mol Tih). Isotacticity of PP obtained in the nanocomposites is in the range of 89%-99%, and its melting temperature is about 159C. The weight-average molecular weight of PP can reach 6.7 105 -7.8 105, and the molecular weight distribution is between 7.7 and 7.9.
TiCl4/MgCl2/clay compound catalyst was prepared by chemical reaction. Exfoliated polypropylene (PP)/clay nanocomposites were synthesized by in situ polymerization with this compound catalyst. Effects of polymerization temperature, polymerization time, propylene pressure, solvent consumption and pre-treat time of catalyst on catalyst activity and catalytic stereospecificity were studied. Under optimal conditions, activity of the nano-compound catalyst is about 88.3 kg/(mol Tih). Isotacticity of PP obtained in the nanocomposites is in the range of 89%-99%, and its melting temperature is about 159C. The weight-average molecular weight of PP can reach 6.7 105 -7.8 105, and the molecular weight distribution is between 7.7 and 7.9.
ALTERNATING COPOLYMERIZATION OF CYCLOHEXENE OXIDE AND CARBON DIOXIDE UNDER COBALT PORPHYRIN CATALYST
2011, 29(5): 602-608
doi: 10.1007/s10118-011-1073-3
Abstract:
Cobalt porphyrin complexes (TPPCoIIIX) (TPP = 5,10,15,20-tetraphenyl-porphyrin; X = halide) in combination with bis(triphenylphosphine) iminium chloride (PPNCl) were used for the copolymerization of cyclohexene oxide and CO2. The highest turnover frequency of 67.2 h-1 was achieved after 13 h at 20C, and the obtained poly(1,2-cyclohexylene carbonate) (PCHC) showed number average molecular weight (Mn) of 10 103. Though the obtained PCHC showed atactic structure, the m-centered tetrads content reached 58.1% at CO2 pressure of 1.0 MPa, and decreased to 51.9% at CO2 pressure of 6.0 MPa, indicating that it was inclined to form atactic polymer at high CO2 pressure.
Cobalt porphyrin complexes (TPPCoIIIX) (TPP = 5,10,15,20-tetraphenyl-porphyrin; X = halide) in combination with bis(triphenylphosphine) iminium chloride (PPNCl) were used for the copolymerization of cyclohexene oxide and CO2. The highest turnover frequency of 67.2 h-1 was achieved after 13 h at 20C, and the obtained poly(1,2-cyclohexylene carbonate) (PCHC) showed number average molecular weight (Mn) of 10 103. Though the obtained PCHC showed atactic structure, the m-centered tetrads content reached 58.1% at CO2 pressure of 1.0 MPa, and decreased to 51.9% at CO2 pressure of 6.0 MPa, indicating that it was inclined to form atactic polymer at high CO2 pressure.
2011, 29(5): 609-614
doi: 10.1007/s10118-011-1076-0
Abstract:
Efficient deep-red organic light-emitting diodes (OLEDs) were investigated based on the blend of poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) with 4,7-bis(5-(7-(9H-carbazol-9-yl)-9,9-dioctyl-9H-fluoren-2-yl)thiophen-2-yl)benzo[c] [1,2,5] thiadiazole (compound 1). By optimizing the blend ratio, the turn-on voltage of the devices was significantly reduced from 4.9 V to 2.4 V. A highest external quantum efficiency of 2.56% was achieved at a blend ratio of 95:5 (wt) for compound 1: MEH-PPV. The CIE coordinate was measured to be (0.70, 0.30), with the luminescence peak at around 680 nm. Based on experimental observations the improvement mechanism is described.
Efficient deep-red organic light-emitting diodes (OLEDs) were investigated based on the blend of poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) with 4,7-bis(5-(7-(9H-carbazol-9-yl)-9,9-dioctyl-9H-fluoren-2-yl)thiophen-2-yl)benzo[c] [1,2,5] thiadiazole (compound 1). By optimizing the blend ratio, the turn-on voltage of the devices was significantly reduced from 4.9 V to 2.4 V. A highest external quantum efficiency of 2.56% was achieved at a blend ratio of 95:5 (wt) for compound 1: MEH-PPV. The CIE coordinate was measured to be (0.70, 0.30), with the luminescence peak at around 680 nm. Based on experimental observations the improvement mechanism is described.
2011, 29(5): 615-626
doi: 10.1007/s10118-011-1071-5
Abstract:
A series of fluorinated phosphatidylcholine polyurethane macromolecular additives were synthesized by solution polymerization using methylenebis(phylene isocyanates) (MDI) and 1,4-butanediol (BDO) as hard segments, a new phoshporycholine, 2-(2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9-hexadecafluoro-10-(2-hydroxyethoxy)decyloxy) ethyl phosphorycholine (HDFOPC) as end-capper, and four polydiols, poly(tetramethylene glycol)s (PTMG), polydimethylsiloxane (PDMS), poly(1,6-hexyl-1,5-pentylcarbonate) (PHPC) and poly(propylene glycol) (PPG) as soft segments, respectively. The chemical structures of the synthesized polyurethanes were characterized by 1H-NMR and FTIR. DSC and DMA were employed to study the phase behavior of these novel polyurethanes due to their great influences on the surface properties, and hence their interactions with bio-systems. The results showed that phase separation of the fluorinated phosphatidylcholine end-capped polyurethanes was increased in comparison with that of normal polyurethanes. The effect of fluorinated phosphatidylcholine end-capped groups on the phase behavior was further demonstrated by analyzing the degree of hydrogen-bonding between hard and soft segments.
A series of fluorinated phosphatidylcholine polyurethane macromolecular additives were synthesized by solution polymerization using methylenebis(phylene isocyanates) (MDI) and 1,4-butanediol (BDO) as hard segments, a new phoshporycholine, 2-(2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9-hexadecafluoro-10-(2-hydroxyethoxy)decyloxy) ethyl phosphorycholine (HDFOPC) as end-capper, and four polydiols, poly(tetramethylene glycol)s (PTMG), polydimethylsiloxane (PDMS), poly(1,6-hexyl-1,5-pentylcarbonate) (PHPC) and poly(propylene glycol) (PPG) as soft segments, respectively. The chemical structures of the synthesized polyurethanes were characterized by 1H-NMR and FTIR. DSC and DMA were employed to study the phase behavior of these novel polyurethanes due to their great influences on the surface properties, and hence their interactions with bio-systems. The results showed that phase separation of the fluorinated phosphatidylcholine end-capped polyurethanes was increased in comparison with that of normal polyurethanes. The effect of fluorinated phosphatidylcholine end-capped groups on the phase behavior was further demonstrated by analyzing the degree of hydrogen-bonding between hard and soft segments.
2011, 29(5): 627-633
doi: 10.1007/s10118-011-1074-2
Abstract:
Mono salicylaldiminato vanadium(III) complexes (1a-1f) [RN ＝CH(ArO)]VCl2(THF)2 (Ar = C6H4 (1a-1e), R = Ph, 1a; R = p-CF3Ph, 1b; R = 2,6-Me2Ph, 1c; R = 2,6-iPr2Ph, 1d; R = cyclohexyl, 1e; Ar = C6H2tBu2(2,4), R = 2,6-iPr2Ph, 1f) and bis(salicylaldiminato) vanadium(III) complexes (2a-2f) [RN ＝ CH(ArO)]2VCl(THF)x (Ar = C6H4 (2a-2e), x = 1 (2a-2e), R = Ph, 2a; R = p-CF3Ph, 2b; R = 2,6-Me2Ph, 2c; R = 2,6-iPr2Ph, 2d; R = cyclohexyl, 2e; Ar = C6H2tBu2(2,4), R = 2,6-iPr2Ph, x = 0, 2f) have been evaluated as the active catalysts for ethylene/1-hexene copolymerization in the presence of Et2AlCl. The ligand substitution pattern and the catalyst structure model significantly influenced the polymerization behaviors such as the catalytic activity, the molecular weight and molecular weight distribution of the copolymers etc. The highest catalytic activity of 8.82 kg PE/(mmolV h) was observed for vanadium catalyst 2d with two 2,6-diisopropylphenyl substituted salicylaldiminato ligands. The copolymer with the highest molecular weight was obtained by using mono salicylaldiminato vanadium catalyst 1f having ligands with tert-butyl at the ortho and para of the aryloxy moiety.
Mono salicylaldiminato vanadium(III) complexes (1a-1f) [RN ＝CH(ArO)]VCl2(THF)2 (Ar = C6H4 (1a-1e), R = Ph, 1a; R = p-CF3Ph, 1b; R = 2,6-Me2Ph, 1c; R = 2,6-iPr2Ph, 1d; R = cyclohexyl, 1e; Ar = C6H2tBu2(2,4), R = 2,6-iPr2Ph, 1f) and bis(salicylaldiminato) vanadium(III) complexes (2a-2f) [RN ＝ CH(ArO)]2VCl(THF)x (Ar = C6H4 (2a-2e), x = 1 (2a-2e), R = Ph, 2a; R = p-CF3Ph, 2b; R = 2,6-Me2Ph, 2c; R = 2,6-iPr2Ph, 2d; R = cyclohexyl, 2e; Ar = C6H2tBu2(2,4), R = 2,6-iPr2Ph, x = 0, 2f) have been evaluated as the active catalysts for ethylene/1-hexene copolymerization in the presence of Et2AlCl. The ligand substitution pattern and the catalyst structure model significantly influenced the polymerization behaviors such as the catalytic activity, the molecular weight and molecular weight distribution of the copolymers etc. The highest catalytic activity of 8.82 kg PE/(mmolV h) was observed for vanadium catalyst 2d with two 2,6-diisopropylphenyl substituted salicylaldiminato ligands. The copolymer with the highest molecular weight was obtained by using mono salicylaldiminato vanadium catalyst 1f having ligands with tert-butyl at the ortho and para of the aryloxy moiety.
2011, 29(5): 634-638
doi: 10.1007/s10118-011-1062-6
Abstract:
Micron-sized nonspherical polymer particles having different morphologies were synthesized by seeded soap-free emulsion polymerization of styrene (St) and ethyleneglycol dimethacrylate (EGDMA, used as a crosslinker) on spherical, linear polystyrene (PS) seed particles. The morphology of the resulting PS/poly(St-co-EGDMA) particles was dependent on the crosslinker concentration and polymerization temperature.
Micron-sized nonspherical polymer particles having different morphologies were synthesized by seeded soap-free emulsion polymerization of styrene (St) and ethyleneglycol dimethacrylate (EGDMA, used as a crosslinker) on spherical, linear polystyrene (PS) seed particles. The morphology of the resulting PS/poly(St-co-EGDMA) particles was dependent on the crosslinker concentration and polymerization temperature.
