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2015 Volume 33 Issue 5
2015, 33(5): 669-673
doi: 10.1007/s10118-015-1631-1
Abstract:
This study aims to investigate the chemical structure and morphology of plasmapolymers produced by deposition of ethylene on the surface of polypropylene. The deposition films (sediments) of ethylene plasma on the surface of polypropylene are nonuniform, and the characterization results indicate the existence of hydroxyl groups and aldehyde (or ketone) groups in the sediments. The sediment of ethylene plasma on the polypropylene surface could induce the growth of -form crystals in the surface layer of polypropylene.
This study aims to investigate the chemical structure and morphology of plasmapolymers produced by deposition of ethylene on the surface of polypropylene. The deposition films (sediments) of ethylene plasma on the surface of polypropylene are nonuniform, and the characterization results indicate the existence of hydroxyl groups and aldehyde (or ketone) groups in the sediments. The sediment of ethylene plasma on the polypropylene surface could induce the growth of -form crystals in the surface layer of polypropylene.
2015, 33(5): 674-679
doi: 10.1007/s10118-015-1630-2
Abstract:
We investigate the statistics of polymer capture by a nanopore using Brownian dynamics simulations. It is found that when the velocity flux is greater than a critical velocity flux, the capture picture is a random selection process, otherwise it tends to a statistical process governed by energetic considerations. In addition, the chain ends capture probability decreases as the chain length increases and satisfies a power-law scaling of P0(N)~N-0.8.
We investigate the statistics of polymer capture by a nanopore using Brownian dynamics simulations. It is found that when the velocity flux is greater than a critical velocity flux, the capture picture is a random selection process, otherwise it tends to a statistical process governed by energetic considerations. In addition, the chain ends capture probability decreases as the chain length increases and satisfies a power-law scaling of P0(N)~N-0.8.
2015, 33(5): 680-687
doi: 10.1007/s10118-015-1635-x
Abstract:
It is found that the fluorescence of aliphatic poly(amido amine)s including linear and hyperbranched ones can be dramatically enhanced by simple aggregation of polymer chains, attributing to the formation of a variety of intra- and interchain clusters with shared lone-pair electrons and the restriction of intramolecular motions. Thanks to the combination of strong solid fluorescence and excellent biocompatibility, these non-conjugated polymers become promising candidates for bioimaging such as bacterial detection. This finding not only extends the aggregation-induced emission (AIE) systems from conjugated compounds to non-conjugated materials, which expands the bioapplication range of AIE systems, but also sheds light on the exploration of novel unconventional luminogens.
It is found that the fluorescence of aliphatic poly(amido amine)s including linear and hyperbranched ones can be dramatically enhanced by simple aggregation of polymer chains, attributing to the formation of a variety of intra- and interchain clusters with shared lone-pair electrons and the restriction of intramolecular motions. Thanks to the combination of strong solid fluorescence and excellent biocompatibility, these non-conjugated polymers become promising candidates for bioimaging such as bacterial detection. This finding not only extends the aggregation-induced emission (AIE) systems from conjugated compounds to non-conjugated materials, which expands the bioapplication range of AIE systems, but also sheds light on the exploration of novel unconventional luminogens.
2015, 33(5): 688-696
doi: 10.1007/s10118-015-1617-z
Abstract:
A new homemade apparatus, i.e. vibration assisted extrusion equipment, is employed to extrude polypropylene. Vibration assisted extrusion is based on the application of a specific macroscopic shear vibration field. Reduction of apparent melt viscosity as a function of vibration frequency is measured at different screw speeds and die temperatures. The effect of the process is investigated by performing mechanical tests, differential scanning calorimetry studies, polarized light microscopy and wide-angle X-ray diffraction. It is found that, compared with conventional extrusion, vibration assisted extrusion could effectively improve the rheological properties of PP melt by incorporating an extra shear vibration field. Both the tensile strength and elongation at break increased under the shear vibration field. For vibration assisted extrusion samples, both the melting temperature and crystallinity increased, accompanied by remarkable grain refinement. Vibration assisted extrusion induced a significantly enhanced bimodal orientation with a high fraction of a*-oriented a-crystallites, while only a limited improvement in the flow direction orientation. A structural model, i.e. bimodal c-axis and a*-axis orientation of PP macromolecular chains, was adopted to explain the experimental results.
A new homemade apparatus, i.e. vibration assisted extrusion equipment, is employed to extrude polypropylene. Vibration assisted extrusion is based on the application of a specific macroscopic shear vibration field. Reduction of apparent melt viscosity as a function of vibration frequency is measured at different screw speeds and die temperatures. The effect of the process is investigated by performing mechanical tests, differential scanning calorimetry studies, polarized light microscopy and wide-angle X-ray diffraction. It is found that, compared with conventional extrusion, vibration assisted extrusion could effectively improve the rheological properties of PP melt by incorporating an extra shear vibration field. Both the tensile strength and elongation at break increased under the shear vibration field. For vibration assisted extrusion samples, both the melting temperature and crystallinity increased, accompanied by remarkable grain refinement. Vibration assisted extrusion induced a significantly enhanced bimodal orientation with a high fraction of a*-oriented a-crystallites, while only a limited improvement in the flow direction orientation. A structural model, i.e. bimodal c-axis and a*-axis orientation of PP macromolecular chains, was adopted to explain the experimental results.
2015, 33(5): 697-708
doi: 10.1007/s10118-015-1619-x
Abstract:
The effects of nanosilica (SiO2) on crystallization and thermal aging behaviors of polyethylene terephthalate (PET) have been studied using differential scanning calorimetry (DSC) and polarized optical microscopy (POM), viscometry, tensile testing and scanning electron microscopy (SEM). For non-isothermal and isothermal crystallizations, the crystallization rate of PET increases considerably with increasing content of SiO2 providing a large number of nucleation sites, but the relative crystallinity of the nanocomposites has little differences with that of neat PET. According to POM observation, the nucleation of PET becomes faster and the nucleation density increases significantly with increasing SiO2 content. For PET and its nanocomposites thermally aged at 190 ℃, the results of intrinsic viscosity, carboxyl content and tensile test show that the degradation rate of PET is reduced with the addition of a small content of SiO2, but the degradation rate increases with further addition of SiO2, owing to the dual effect of SiO2 on PET degradation.
The effects of nanosilica (SiO2) on crystallization and thermal aging behaviors of polyethylene terephthalate (PET) have been studied using differential scanning calorimetry (DSC) and polarized optical microscopy (POM), viscometry, tensile testing and scanning electron microscopy (SEM). For non-isothermal and isothermal crystallizations, the crystallization rate of PET increases considerably with increasing content of SiO2 providing a large number of nucleation sites, but the relative crystallinity of the nanocomposites has little differences with that of neat PET. According to POM observation, the nucleation of PET becomes faster and the nucleation density increases significantly with increasing SiO2 content. For PET and its nanocomposites thermally aged at 190 ℃, the results of intrinsic viscosity, carboxyl content and tensile test show that the degradation rate of PET is reduced with the addition of a small content of SiO2, but the degradation rate increases with further addition of SiO2, owing to the dual effect of SiO2 on PET degradation.
2015, 33(5): 709-720
doi: 10.1007/s10118-015-1621-3
Abstract:
We designed and synthesized a triarm star-shaped rod-rod block copolymer (BCP), (poly{2,5-bis[(4-methoxyphenyl)-oxycarbonyl]styrene}-block-poly(-benzyl-L-glutamate))3, (PMPCS-b-PBLG)3. The triarm core with three PMPCS-N3 segments was prepared by copper-mediated atom transfer radical polymerization of 2,5-bis[(4-methoxyphenyl)-oxycarbonyl]styrene initiated by a trifunctional initiator and a subsequent azide reaction. And the PBLG block with alkyne functionality was synthesized through ring-opening polymerization of -benzyl-L-glutamate N-carboxyanhydride initiated by propargylamine. Finally, Huisgen's 1,3-dipolar cycloaddition was employed to combine the triarm (PMPCS-N3)3 and PBLG segments. The chemical structure of the BCP was confirmed by 1H-NMR spectroscopy, Fourier-transform infrared spectroscopy, and gel permeation chromatographic analysis. Results from differential scanning calorimetry, polarized light microscopy, one-dimensional and two-dimensional wide-angle X-ray diffraction, and transmission electron microscopy techniques demonstrate that the triarm star-shaped rod-rod BCP self-assembles into a hexagon-in-lamella morphology, with the PMPCS block in the columnar nematic phase and the PBLG block in the hexagonal columnar arrangement packed in bilayers due to the rigid nature of the two blocks and the covalent connections in the star-shaped BCP.
We designed and synthesized a triarm star-shaped rod-rod block copolymer (BCP), (poly{2,5-bis[(4-methoxyphenyl)-oxycarbonyl]styrene}-block-poly(-benzyl-L-glutamate))3, (PMPCS-b-PBLG)3. The triarm core with three PMPCS-N3 segments was prepared by copper-mediated atom transfer radical polymerization of 2,5-bis[(4-methoxyphenyl)-oxycarbonyl]styrene initiated by a trifunctional initiator and a subsequent azide reaction. And the PBLG block with alkyne functionality was synthesized through ring-opening polymerization of -benzyl-L-glutamate N-carboxyanhydride initiated by propargylamine. Finally, Huisgen's 1,3-dipolar cycloaddition was employed to combine the triarm (PMPCS-N3)3 and PBLG segments. The chemical structure of the BCP was confirmed by 1H-NMR spectroscopy, Fourier-transform infrared spectroscopy, and gel permeation chromatographic analysis. Results from differential scanning calorimetry, polarized light microscopy, one-dimensional and two-dimensional wide-angle X-ray diffraction, and transmission electron microscopy techniques demonstrate that the triarm star-shaped rod-rod BCP self-assembles into a hexagon-in-lamella morphology, with the PMPCS block in the columnar nematic phase and the PBLG block in the hexagonal columnar arrangement packed in bilayers due to the rigid nature of the two blocks and the covalent connections in the star-shaped BCP.
2015, 33(5): 721-731
doi: 10.1007/s10118-015-1620-4
Abstract:
Three-dimensional (3-D) coarse-grained Monte Carlo algorithms were used to simulate the conformations of swollen hydrogels formed by copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC). The simulation consists of three successive steps including diffusion, cross-linking and relaxation. The cross-linking of multifunctional reaction sites is simulated instantly followed by fast crosslinking. In order to explore the validity of this approach pristine poly(ethylene glycol) (PEG) hydrogels with tri- and tetra-functional reaction sites (G3 and G4 respectively) were prepared and characterized. The data from the simulations were found to be in good agreement with experimental results such as PEG lengths between crosslinks, pore volume and pore radius distribution, indicating the validity of the modeling algorithm. The calculated PEG lengths in G3 and G4 networks are close ( 4.6 nm). The 3-D visual topological structure of the hydrogel network suggests that the ideal hydrogel is far from cubic, diamond or any well defined structures of regular repeating cells.
Three-dimensional (3-D) coarse-grained Monte Carlo algorithms were used to simulate the conformations of swollen hydrogels formed by copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC). The simulation consists of three successive steps including diffusion, cross-linking and relaxation. The cross-linking of multifunctional reaction sites is simulated instantly followed by fast crosslinking. In order to explore the validity of this approach pristine poly(ethylene glycol) (PEG) hydrogels with tri- and tetra-functional reaction sites (G3 and G4 respectively) were prepared and characterized. The data from the simulations were found to be in good agreement with experimental results such as PEG lengths between crosslinks, pore volume and pore radius distribution, indicating the validity of the modeling algorithm. The calculated PEG lengths in G3 and G4 networks are close ( 4.6 nm). The 3-D visual topological structure of the hydrogel network suggests that the ideal hydrogel is far from cubic, diamond or any well defined structures of regular repeating cells.
2015, 33(5): 732-742
doi: 10.1007/s10118-015-1628-9
Abstract:
Composites of polyaniline (PAn) and epoxide polysiloxane (EPSi) are reported for the first time. EPSi is designed, synthesized and N-grafted onto the PAn backbone through covalent bonds. As-prepared EPSi-g-PAn composites are soluble in organic solvents and the corresponding films can be easily produced via a simple solution-casting procedure. The composite films combine the mechanical characteristics of EPSi and the chemical properties of PAn, enabling the facile introduction of the noble metal particles. The successful fabrication of the composites is confirmed by the investigation of the molecular structure, crystalline structure and microstructure of the materials. The resulting composite films containing noble metal particles are employed as the catalysts for the hydrogenation of phenol to produce cyclohexanone, which exhibit the convenience and recyclability for usage as well as the high catalytic activities, including the conversion ratio of 97%-100% and the selectivity as high as 84%-98%. The present work not only provides a new method to improve the processability of the conducting polymers but also describes a kind of composite materials that may display outstanding preformances in industrial catalysis.
Composites of polyaniline (PAn) and epoxide polysiloxane (EPSi) are reported for the first time. EPSi is designed, synthesized and N-grafted onto the PAn backbone through covalent bonds. As-prepared EPSi-g-PAn composites are soluble in organic solvents and the corresponding films can be easily produced via a simple solution-casting procedure. The composite films combine the mechanical characteristics of EPSi and the chemical properties of PAn, enabling the facile introduction of the noble metal particles. The successful fabrication of the composites is confirmed by the investigation of the molecular structure, crystalline structure and microstructure of the materials. The resulting composite films containing noble metal particles are employed as the catalysts for the hydrogenation of phenol to produce cyclohexanone, which exhibit the convenience and recyclability for usage as well as the high catalytic activities, including the conversion ratio of 97%-100% and the selectivity as high as 84%-98%. The present work not only provides a new method to improve the processability of the conducting polymers but also describes a kind of composite materials that may display outstanding preformances in industrial catalysis.
2015, 33(5): 743-753
doi: 10.1007/s10118-015-1622-2
Abstract:
Chiral enediynes with pendant chiral amino ester groups are synthesized through Sonogashira reactions and subjected to thermal triggered Bergman cyclization at elevated temperatures either in bulk or in solvents to produce chiral polyphenylenes. The disappearance of enediyne monomers are evidenced by FTIR and NMR spectroscopies. The formation of polyphenylenes is further confirmed by UV-Vis and MALDI-TOF mass spectroscopies (MS). Isotope pattern analysis of the MS spectra shows that the polymers prepared in solvents are terminated by the solvent molecules, whereas the chain ends of the polymers prepared in bulk consist of considerable amount of unmasked free radicals, which is further confirmed by EPR analysis. Circular dichroism (CD) spectra of the chiral polymers show blue shifts of the Cotton peaks, indicating the occurrence of the cycloaromatization reaction. A new set of peaks mirrored at the horizontal axis show up in the long wavelength range, which are assigned to main chain chirality of the polyphenylenes.
Chiral enediynes with pendant chiral amino ester groups are synthesized through Sonogashira reactions and subjected to thermal triggered Bergman cyclization at elevated temperatures either in bulk or in solvents to produce chiral polyphenylenes. The disappearance of enediyne monomers are evidenced by FTIR and NMR spectroscopies. The formation of polyphenylenes is further confirmed by UV-Vis and MALDI-TOF mass spectroscopies (MS). Isotope pattern analysis of the MS spectra shows that the polymers prepared in solvents are terminated by the solvent molecules, whereas the chain ends of the polymers prepared in bulk consist of considerable amount of unmasked free radicals, which is further confirmed by EPR analysis. Circular dichroism (CD) spectra of the chiral polymers show blue shifts of the Cotton peaks, indicating the occurrence of the cycloaromatization reaction. A new set of peaks mirrored at the horizontal axis show up in the long wavelength range, which are assigned to main chain chirality of the polyphenylenes.
2015, 33(5): 754-762
doi: 10.1007/s10118-015-1623-1
Abstract:
A biaxial stretching equipment was designed and constructed to enable fundamental studies of the relationship between film processing conditions and structures of oriented film products. With programmable drive motors and scissor-like mechanism, all stretching modes, including uniaxial stretching with constant and free width, simultaneous and sequential biaxial stretching, can be applied to a square-shaped sheet. Parameters related to film stretching manufacturing, such as temperature, draw ratio and stretching speed can be set independently to meet the requirement of different polymers. The force information during stretching is recorded by two miniature tension sensors in two directions independently, which can monitor the mechanical stimulus and stress response. Using this equipment, experiments are conducted to investigate the influence of stretching parameters on the structure of polypropylene films, which provides an effective method to tailor the processing conditions to obtain the films with desired properties.
A biaxial stretching equipment was designed and constructed to enable fundamental studies of the relationship between film processing conditions and structures of oriented film products. With programmable drive motors and scissor-like mechanism, all stretching modes, including uniaxial stretching with constant and free width, simultaneous and sequential biaxial stretching, can be applied to a square-shaped sheet. Parameters related to film stretching manufacturing, such as temperature, draw ratio and stretching speed can be set independently to meet the requirement of different polymers. The force information during stretching is recorded by two miniature tension sensors in two directions independently, which can monitor the mechanical stimulus and stress response. Using this equipment, experiments are conducted to investigate the influence of stretching parameters on the structure of polypropylene films, which provides an effective method to tailor the processing conditions to obtain the films with desired properties.
2015, 33(5): 763-771
doi: 10.1007/s10118-015-1624-0
Abstract:
Herein, cisplatin-loaded poly(L-glutamic acid)-g-methoxy poly(ethylene glycol) nanoparticles were evaluated as a potential chemotherapeutic agent against osteosarcoma by using alone or with an iRGD (internalizing RGD, CRGDKDPDC). The release rate of platinum from the cisplatin-loaded nanoparticles CDDP/PLG160-g-mPEG2K (CDDP-NPs) accelerated with the increase of the acidity of the environment. In vitro test demonstrated that CDDP-NPs could inhibit the proliferation of MNNG/Hos osteosarcoma cells with IC50 (72 h) of 12.2 gmL-1. In vivo test for MNNG/Hos osteosarcoma tumor bearing mice exhibited that CDDP-NPs had comparable or slightly higher efficacy but significantly lower side effects in comparison with free CDDP. The coadministration of iRGD could further enhance the anticancer efficacy of CDDP-NPs against MNNG/Hos osteosarcoma without bringing obvious side effects. Therefore, CDDP-NPs using alone or with iRGD have great potential for the treatment of osteosarcoma.
Herein, cisplatin-loaded poly(L-glutamic acid)-g-methoxy poly(ethylene glycol) nanoparticles were evaluated as a potential chemotherapeutic agent against osteosarcoma by using alone or with an iRGD (internalizing RGD, CRGDKDPDC). The release rate of platinum from the cisplatin-loaded nanoparticles CDDP/PLG160-g-mPEG2K (CDDP-NPs) accelerated with the increase of the acidity of the environment. In vitro test demonstrated that CDDP-NPs could inhibit the proliferation of MNNG/Hos osteosarcoma cells with IC50 (72 h) of 12.2 gmL-1. In vivo test for MNNG/Hos osteosarcoma tumor bearing mice exhibited that CDDP-NPs had comparable or slightly higher efficacy but significantly lower side effects in comparison with free CDDP. The coadministration of iRGD could further enhance the anticancer efficacy of CDDP-NPs against MNNG/Hos osteosarcoma without bringing obvious side effects. Therefore, CDDP-NPs using alone or with iRGD have great potential for the treatment of osteosarcoma.
2015, 33(5): 772-782
doi: 10.1007/s10118-015-1625-z
Abstract:
The mechanism of char formation effect of zinc acetylacetonate (Zn(acac)2) on acrylonitrile-butadiene-styrene copolymer (ABS) was studied. Thermal gravimetric analysis (TGA) was used to study the mass loss and char yield of ABS composites. In situ temperature-dependent Fourier transform infrared spectroscopy (FTIR) was used to characterize the chemical change during thermal decomposition. Roman spectroscopy and scanning electron microscopy (SEM) were applied to characterize the structure and morphology of the char after combustion. Results showed that the presence of Zn(acac)2 not only slowed down thermal decomposition of the ABS composites, but also increased the charred residue. A more compact and denser char layer with higher graphitization degree was formed for ABS composites with Zn(acac)2. To study the char formation mechanism of Zn(acac)2 on ABS, thermal decomposition was analyzed for the composites of Zn(acac)2 with PB, PS and SAN, respectively. Also, the chemical structure change was investigated for Zn(acac)2 during thermal decomposition. Based on these results, it was deduced that the increase of char yield of ABS composites was probably attributed to the interaction between the units of acrylonitrile in ABS and zinc acetate, produced during the thermal decomposition of Zn(acac)2. A proposed mechanism for crosslinking and the subsequent char formation was presented.
The mechanism of char formation effect of zinc acetylacetonate (Zn(acac)2) on acrylonitrile-butadiene-styrene copolymer (ABS) was studied. Thermal gravimetric analysis (TGA) was used to study the mass loss and char yield of ABS composites. In situ temperature-dependent Fourier transform infrared spectroscopy (FTIR) was used to characterize the chemical change during thermal decomposition. Roman spectroscopy and scanning electron microscopy (SEM) were applied to characterize the structure and morphology of the char after combustion. Results showed that the presence of Zn(acac)2 not only slowed down thermal decomposition of the ABS composites, but also increased the charred residue. A more compact and denser char layer with higher graphitization degree was formed for ABS composites with Zn(acac)2. To study the char formation mechanism of Zn(acac)2 on ABS, thermal decomposition was analyzed for the composites of Zn(acac)2 with PB, PS and SAN, respectively. Also, the chemical structure change was investigated for Zn(acac)2 during thermal decomposition. Based on these results, it was deduced that the increase of char yield of ABS composites was probably attributed to the interaction between the units of acrylonitrile in ABS and zinc acetate, produced during the thermal decomposition of Zn(acac)2. A proposed mechanism for crosslinking and the subsequent char formation was presented.
2015, 33(5): 783-791
doi: 10.1007/s10118-015-1555-9
Abstract:
Four thiophene derivatives were prepared by replacing the 3,4 positions of thiophene by ―OCH3, ―CH3 ―COOCH3 and ―CN, respectively. The polycondensations via direct arylation took place between the four thiophene derivatives and 2,7-dibromo-9,9-dioctylfluorene under six various catalytic conditions to investigate the substituent effects. The substituent can affect the electron cloud density of the active C―H bond, which can be monitored by the NMR chemical shift. The experimental results show that the reactivity decreases with increasing the chemical shift of active C―H bonds in the four thiophene derivatives, and thus can promote the direct arylation polycondensation. This phenomenon is explained by the electrophilic aromatic substitution (SEAr) mechanism. UV-Visible absorption and photoluminescence were studied to investigate the substituent effect on optical properties of the four copolymers. The results show that these alternating fluorene-thiophene copolymers with different substituents are good fluorescent materials and promising in PLED applications.
Four thiophene derivatives were prepared by replacing the 3,4 positions of thiophene by ―OCH3, ―CH3 ―COOCH3 and ―CN, respectively. The polycondensations via direct arylation took place between the four thiophene derivatives and 2,7-dibromo-9,9-dioctylfluorene under six various catalytic conditions to investigate the substituent effects. The substituent can affect the electron cloud density of the active C―H bond, which can be monitored by the NMR chemical shift. The experimental results show that the reactivity decreases with increasing the chemical shift of active C―H bonds in the four thiophene derivatives, and thus can promote the direct arylation polycondensation. This phenomenon is explained by the electrophilic aromatic substitution (SEAr) mechanism. UV-Visible absorption and photoluminescence were studied to investigate the substituent effect on optical properties of the four copolymers. The results show that these alternating fluorene-thiophene copolymers with different substituents are good fluorescent materials and promising in PLED applications.
2015, 33(5): 792-796
doi: 10.1007/s10118-015-1629-8
Abstract:
-Imidophosphonamido ligated lutetium alkyl complex (NPNDipp)Lu(CH2SiMe3)2(THF) (NPNDipp = Ph2P(NC6H3iPr2-2,6)2) with the activation of AliBu3 and [Ph3C][B(C6F5)4] exhibited high catalytic activity, medium syndio-(rr = 66%) but remarkably high 3,4-regioselectivity for the polymerization of -myrcene (MY). In sharp contrast, high isotactic 3,4-polymyrcene (PMY) (mm = 95%) was obtained by the precursor (NPNEt)Lu(CH2SiMe3)2(THF) (NPNEt = PPh2(NC6H3iPr2-2,6)(NC6H4-Et-2)) with less bulky substituents on the N-aryl ring.
-Imidophosphonamido ligated lutetium alkyl complex (NPNDipp)Lu(CH2SiMe3)2(THF) (NPNDipp = Ph2P(NC6H3iPr2-2,6)2) with the activation of AliBu3 and [Ph3C][B(C6F5)4] exhibited high catalytic activity, medium syndio-(rr = 66%) but remarkably high 3,4-regioselectivity for the polymerization of -myrcene (MY). In sharp contrast, high isotactic 3,4-polymyrcene (PMY) (mm = 95%) was obtained by the precursor (NPNEt)Lu(CH2SiMe3)2(THF) (NPNEt = PPh2(NC6H3iPr2-2,6)(NC6H4-Et-2)) with less bulky substituents on the N-aryl ring.
