7 research outputs found

    Sequence Features of Sequence-Controlled Polymers Synthesized by 1,1-Diphenylethylene Derivatives with Similar Reactivity during Living Anionic Polymerization

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    Living anionic polymerization (LAP) is the primary representative method of living polymerization and exhibits the ability to synthesize sequence-regulated functionalized polymers. However, there has always been a lack of special features for LAP to guide these cutting-edge syntheses in sequence-controlled polymers. In this study, the copolymerizations of a series of alkyl-substituted 1,1-diphenylethylene derivatives (DPE-alkyls), which display similar reactivities but different structures, and St were performed. In addition, the processes of whole chain propagation were monitored by the <i>in situ</i> <sup>1</sup>H NMR method. The results show that changing the alkyl type of DPE-alkyls has little influence on their sequence distributions during copolymerization. Therefore, we could deduce a reasonable principle called “sequence equivalence” in LAP: the copolymers of different DPE derivatives and St would have identical sequence structures when DPE derivatives exhibit exactly the same reactivity ratio (<i>r</i><sub>St</sub>) during the copolymerization under the same conditions. Furthermore, the combination of <i>in situ</i> <sup>1</sup>H NMR experiments and kinetic Monte Carlo model (KMC) simulations was conducted synchronously. The results of simulations show that the KMC model not only can simulate detailed information for LAP of DPE derivative and St but also could quantify the precision of the corresponding sequence distributions. Additionally, the KMC model that we constructed for the simulation of sequence control in LAP can give us a new insight into the possibility of sequence tailoring. Next, the relationship among the glass transition temperatures (<i>T</i><sub>g</sub>s), types of alkyl substituent, and sequence structures of DPE derivative units in the chains was investigated. Through DSC analysis, this study’s results indicated that polymers with similar sequences but different alkyl substituents present contrasting differences in thermal property. These results could provide a broader understanding of the thermal properties of polymers

    Biobased Inverse Vulcanized Polymer from Magnolol as a Multifunctional Ingredient for Carbon-Black-Reinforced Rubber Composites

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    Inverse vulcanization provides a facile route to transform industrial byproduct sulfur into attractive polymeric materials with a variety of applications. Herein, an inverse vulcanized copolymer (PSM) was synthesized by copolymerization of biomass magnolol and sulfur. PSM presents outstanding intrinsic flame retardancy by the formation of a highly pyrolysis-resistant carbonaceous material during combustion. Especially, it can serve as a multifunctional ingredient when utilized in rubber composites. The presence of polysulfide segments and biphenol moieties enables PSM to cross-link rubber effectively and react with the oxygenic groups on the surface of carbon black (CB), thus resulting in the improvement of CB dispersion and stronger interfacial interaction between a rubber matrix and nanofillers than the conventional sulfur-cross-linked rubber composite. Incorporation of PSM also significantly retards the thermo-oxidation aging of the composites due to its radical scavenging capability. Moreover, the dynamic covalent polysulfide segments in the system confer the PSM-cross-linked rubber material reprocessability and recyclability

    Biobased Inverse Vulcanized Polymer from Magnolol as a Multifunctional Ingredient for Carbon-Black-Reinforced Rubber Composites

    No full text
    Inverse vulcanization provides a facile route to transform industrial byproduct sulfur into attractive polymeric materials with a variety of applications. Herein, an inverse vulcanized copolymer (PSM) was synthesized by copolymerization of biomass magnolol and sulfur. PSM presents outstanding intrinsic flame retardancy by the formation of a highly pyrolysis-resistant carbonaceous material during combustion. Especially, it can serve as a multifunctional ingredient when utilized in rubber composites. The presence of polysulfide segments and biphenol moieties enables PSM to cross-link rubber effectively and react with the oxygenic groups on the surface of carbon black (CB), thus resulting in the improvement of CB dispersion and stronger interfacial interaction between a rubber matrix and nanofillers than the conventional sulfur-cross-linked rubber composite. Incorporation of PSM also significantly retards the thermo-oxidation aging of the composites due to its radical scavenging capability. Moreover, the dynamic covalent polysulfide segments in the system confer the PSM-cross-linked rubber material reprocessability and recyclability

    Biobased Inverse Vulcanized Polymer from Magnolol as a Multifunctional Ingredient for Carbon-Black-Reinforced Rubber Composites

    No full text
    Inverse vulcanization provides a facile route to transform industrial byproduct sulfur into attractive polymeric materials with a variety of applications. Herein, an inverse vulcanized copolymer (PSM) was synthesized by copolymerization of biomass magnolol and sulfur. PSM presents outstanding intrinsic flame retardancy by the formation of a highly pyrolysis-resistant carbonaceous material during combustion. Especially, it can serve as a multifunctional ingredient when utilized in rubber composites. The presence of polysulfide segments and biphenol moieties enables PSM to cross-link rubber effectively and react with the oxygenic groups on the surface of carbon black (CB), thus resulting in the improvement of CB dispersion and stronger interfacial interaction between a rubber matrix and nanofillers than the conventional sulfur-cross-linked rubber composite. Incorporation of PSM also significantly retards the thermo-oxidation aging of the composites due to its radical scavenging capability. Moreover, the dynamic covalent polysulfide segments in the system confer the PSM-cross-linked rubber material reprocessability and recyclability

    Assessing the Sequence Specificity in Thermal and Polarized Optical Order of Multiple Sequence-Determined Liquid Crystal Polymers

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    To assess the inherent effect of sequence distribution on thermal and polarized optical order, side-chain liquid crystal polymers (SCLCPs) with precise side-chain sequence control were synthesized and characterized. Multiple uniform (M-U), alternating (M-A), gradient (M-G), and interval (M-I) polymers were conveniently used as well-designed Si–H functional backbones, and the treatment of these sequence-determined backbones with mesogenic moieties was conducted via highly efficient hydrosilylation to obtain sequence-determined SCLCPs with well-designed molecular compositions and narrow polydispersity index (PDI). The molecular arrangement of multiple analogous architectures was constructed, which provided the unique opportunity to comprehensively study how the sequence impacts liquid crystalline (LC) behavior. The general trends that the thermal and polarized optical order are significantly sensitive to sequence specificity in the order M-U > M-A > M-G > M-I for a given SCLCPs with a similar number or similar overall concentration of mesogenic moieties are deduced. Here, SCLCPs with important sequence control led to increased understanding of interior structure–property relations owing to the specific spacing between adjacent LC pendants. As such, this spacing will be recognized as an essential parameter that determines LC properties that are of interest to be explored

    Effect of Topology and Composition on Liquid Crystal Order and Self-Assembly Performances Driven by Asynchronously Controlled Grafting Density

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    A series of thermo-tunable liquid crystal block copolymers (LCBCs) with well-designed architectures were successfully synthesized. Linear/star poly­[4-(4-vinylphenyl)-1-butene]-<i>block</i>-polybutadiene (PVSt-<i>co</i>-PB) moieties were obtained using living anionic copolymerization of 4-(4-vinylphenyl)-1-butene with butadiene, and topological [PVSt-<i>co</i>-PB]-LCBCs were generated through the adherence of mesogenic moiety via facile hydrosilylation. The PVSt LC block had well-defined grafting densities of approximately 100%, 70%, and 40%, whereas the PB LC block had an asynchronously tunable grafting density. This work included comprehensive studies on their self-assembly and yielded some interesting results. The influences of topologies and compositions on the phase transition behaviors and polarized optical performances of the resulting LCBCs that were driven by asynchronously controlled grafting density were carefully illustrated. The LCBCs with controlled molecular weight (MW) and narrow PDI showed wider LC phase ranges (Δ<i>T</i>) and a high tunability was added into the construction to aid thermos-responsive devices. The wide Δ<i>T</i> and high thermo-stability were demonstrated to be complementary between two LC blocks. However, the response-time and aggregation morphology in POM showed close similarity to LC blocks and showed a gradient in temperature-dependent changes with the PB LC block at a lower temperature and the PVSt LC block at a higher temperature. It is common for LC texture to change with varying temperature, whereas the gradient switching process was unique to LC blocks, which was further confirmed by temperature-dependent WAXD. In particular, the structural reorganization was determined to be driven by asynchronous grafting density by measuring the temperature-variation AFM, in that the asynchronous-tunable motion between LC blocks facilitates small phase separation

    Strategies for Tailoring LC-Functionalized Polymer: Probe Contribution of [<i>Si–O–Si</i>] versus [<i>Si–C</i>] Spacer to Thermal and Polarized Optical Performance “Driven by” Well-Designed Grafting Density and Precision in Flexible/Rigid Matrix

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    A versatile strategy is highly desired to prepare well-designed side chain liquid crystal polymers (SCLCPs). Two rigid and topological SiH/Vinyl-functionalized polystyrenes (PSs), namely poly­(4-vinylphenyl­dimethylsilane) (PVPDMS) and poly­(4-vinyl­phenyl-1-butene) (PVSt), were synthesized via anionic polymerization (AP) and detailed; subsequently, Vinyl/SiH terminated LCs were treated with PVSt/PVPDMS via hydrosilylation to yield SCLCPs bearing [<i>Si–O–Si</i>]/[<i>Si–C</i>] spacers. Herein, well-designed grafting density, evaluated by <sup>1</sup>H NMR, was readily performed by the varying SiH to Vinyl feed mole ratio. The design systematically probes a cooperative effect of architectures on properties and allows for precision in flexible/rigid matrixes. Regardless, PB/PS systems with saturated addition displayed the best performances. Fundamentally, the study compared the dependence of polarized optical and thermal performances on [<i>Si–O–Si</i>] versus [<i>Si–C</i>] spacer, which submitted to be driven by grafting density, providing the first access to tailoring polymer. SCLCPs exhibited essentially constant S<sub>m</sub>A, but inconsistent dynamic of spacer-induced contribution, in which Δ<i>T</i> was the same in complete addition as if nothing with spacer; surprisingly, followed by decreased grafting density, the decreasing trend in Δ<i>T</i> of [<i>Si–O–Si</i>] as spacer was fast, while that of [<i>Si–C</i>] was slow. This phenomenon was further confirmed by POM. Furthermore, [<i>Si–O–Si</i>] was desired to obtain lower <i>T</i><sub>g</sub> and applicable to the advantageous “decoupling effect”. Endeavor for tailoring SCLCPs and regulating devices, the appropriate spacer and grafting density advanced to an effective role
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