Anionic Polymerization Of Butadiene Research Articles

Correction to “Calcium–Lithium Systems as Innovative Bimetallic Initiators for the Anionic Polymerization of Butadiene: Toward Control and High 1,4-Trans Microstructure”

Correction to “Calcium–Lithium Systems as Innovative Bimetallic Initiators for the Anionic Polymerization of Butadiene: Toward Control and High 1,4-Trans Microstructure”

Calcium–Lithium Systems as Innovative Bimetallic Initiators for the Anionic Polymerization of Butadiene: Toward Control and High 1,4-trans Microstructure

Calcium–Lithium Systems as Innovative Bimetallic Initiators for the Anionic Polymerization of Butadiene: Toward Control and High 1,4-trans Microstructure

Soft-sensor estimation via parameter fitting and dynamic optimization in an experimental batch butadiene homopolymerization reactor

In this work, we address modeling and experimental tasks to develop an industrial process for the anionic polymerization of butadiene, which is a key compound used in the production of high-performance tires. The aim of this study was to determine the processing conditions that lead to the efficient manufacturing of polybutadiene. Accordingly, an experimental polymer reaction facility was constructed to record both butadiene conversion and temperature profiles. A first-principles dynamic mathematical model was developed to track the measurement variables as best as possible. To improve the tracking of recorded variables, some process variables were deployed as manipulated variables. Because good experimental tracking was not acceptable, we used the soft-sensor approach to estimate some additional degrees of freedom. The estimation task was performed by describing the problem as a dynamic optimization problem. The results clearly show that the optimization and control tasks of butadiene polymerization reaction facilities are demanding and require good experimental information to develop reliable mathematical models that can be leveraged to speed up the development of such industrial polymerization systems.

Investigating The Kinetics of Anionic Polymerization of Butadiene in Presence of 1,2‐diethoxypropane Using Online Near‐Infrared Spectroscopy

AbstractOnline near‐infrared spectroscopy technique is employed to investigate the kinetics of the anionic polymerization of butadiene with n‐butyllithium initiator in the presence of the microstructure modifier 1,2‐diethoxypropane (DEP) in cyclohexane solvent. A phenomenological kinetic model is developed to describe the anionic polymerization process in the presence of DEP, and its influence on the microstructure of polybutadiene under different conditions is determined.

Threading-the-Needle: Compatibilization of HDPE/iPP blends with butadiene-derived polyolefin block copolymers

Management of the plastic industry is a momentous challenge, one that pits enormous societal benefits against an accumulating reservoir of nearly indestructible waste. A promising strategy for recycling polyethylene (PE) and isotactic polypropylene (iPP), constituting roughly half the plastic produced annually worldwide, is melt blending for reformulation into useful products. Unfortunately, such blends are generally brittle and useless due to phase separation and mechanically weak domain interfaces. Recent studies have shown that addition of small amounts of semicrystalline PE-iPP block copolymers (ca. 1 wt%) to mixtures of these polyolefins results in ductility comparable to the pure materials. However, current methods for producing such additives rely on expensive reagents, prohibitively impacting the cost of recycling these inexpensive commodity plastics. Here, we describe an alternative strategy that exploits anionic polymerization of butadiene into block copolymers, with subsequent catalytic hydrogenation, yielding E and X blocks that are individually melt miscible with PE and iPP, where E and X are poly(ethylene-ran-ethylethylene) random copolymers with 6 wt% and 90 wt% ethylethylene repeat units, respectively. Cooling melt blended mixtures of PE and iPP containing 1 wt% of the triblock copolymer EXE of appropriate molecular weight, results in mechanical properties competitive with the component plastics. Blend toughness is obtained through interfacial topological entanglements of the amorphous X polymer and semicrystalline iPP, along with anchoring of the E blocks through cocrystallization with the PE homopolymer. Significantly, EXE can be inexpensively produced using currently practiced industrial scale polymerization methods, offering a practical approach to recycling the world's top two plastics.

Switch from Anionic Polymerization to Coordinative Chain Transfer Polymerization: A Valuable Strategy to Make Olefin Block Copolymers.

Anionic polymerization of butadiene or/and styrene is performed with lithium initiators, functional or not. The polymer chains are subsequently transferred to magnesium. The resulting polymeryl-magnesium compounds were combined with {(Me2 Si(C13 H8 )2 )Nd(μ-BH4 )[(μ-BH4 )Li(THF)]}2 metallocene complex to act as macromolecular chain transfer agents (macroCTAs) in coordinative chain transfer polymerization (CCTP) of ethylene (E) or its copolymerization (CCTcoP) with butadiene (B). Block copolymers were produced for the first time by this switch from anionic polymerization to CCTP. Hard and soft blocks such as PB, polystyrene (PS), poly(styrene-co-butadiene) (SBR) obtained by anionic polymerization and PE or poly(ethylene-co-butadiene) (EBR) produced by CCT(co)P were combined and the corresponding structures were characterized.

Structure of terminal units of polybutadiene synthesized via anionic mechanism

The structure of head and end groups of the polybutadiene synthesized by anionic polymerization of butadiene using tert-butyllithium as an initiator has been established using methods of NMR spectroscopy with T2-filter as well as 2D 1H, 13C HMBC and HSQC NMR spectroscopy. The spectral signals of head groups, which consist of tert-butyl groups connected with cis-1,4, trans-1,4 or 1,2-units of polybutadiene chain, were identified for the first time. A new method for the quantitative calculation of the content of head and end groups with different microstructures was proposed. It was shown that the total content of 1,4-units (both cis-1,4 and trans-1,4) in terminal groups is considerably higher than that in a main chain of polybutadiene.

Thermal runaway risk analysis in styrenic block copolymer production

AbstractStyrenic butadiene block copolymers are an important family of commercial materials in the category of thermoplastic elastomers. These elastomers are made of separate polymeric blocks. At the beginning, there is a hard polystyrene block and in the middle, there is a polybutadiene block. Butadiene is the monomer in highest concentration in regular styrenic block copolymers. The main risk linked to the production of styrenic block copolymers on an industrial scale is the loss of control of the reactor temperature, which may lead to a temperature increase resulting in a pressure increase above its design pressure during the formation of the polybutadiene block. Fatal accidents have occurred in some chemical plants due to runaway butadiene polymerization. Critical parameters that characterize thermal runaway for the anionic polymerization of butadiene in batch reactors were established for different scale reactors: laboratory, pilot and industrial reactors. Runaway and safe conditions are identified based on the pattern of temperature and conversion trajectories near complete butadiene conversion. The resulting is useful for establishing runaway diagrams for the anionic polymerization of butadiene in batch reactors using dimensionless parameters: reaction sensitivity and cooling intensity.

Anionic polymerization of butadiene by dialkylmagnesium / alkali metal alkoxide systems in apolar medium: Polybutadiene microstructure and polymerization control

Lithium based anionic polymerization of butadiene in apolar media allows the obtention of polybutadiene with a high vinyl content by using polar modifier or alkali metal alkoxide. For instance, butadiene polymerization with alkyllithium and potassium tert-pentoxide produces polybutadiene with 50% of vinyl content. The aim of this paper is to develop an approach without any alkyllithium moieties in order to synthesize polybutadiene with a high vinyl content (50%–70%) in a controlled way. To do so bi-metallic systems based on di-n-butylmagnesium in association with potassium or sodium tert-pentoxide were studied in apolar medium. The influence of parameters such as the initiator preformation time and the [Mt]/[Mg] ratio were assessed (Mt = K, Na). The potassium tert-pentoxide-based system was found to produce polybutadienes in a controlled way with 50% of vinyl content, while polybutadienes with up to 70% of vinyl content were obtained in a controlled way with Na based systems.

Accessible microstructures of polybutadiene by anionic polymerization

Mechanical and viscoelastic properties of polybutadiene-based rubber materials are highly dependent on polybutadiene microstructure along with molar mass, dispersity, polymer architecture and styrene content for copolymers. In addition, the living character of anionic polymerization of butadiene allows the precise chain-end functionalization and synthesis of block copolymers. Knowing that mainly the nature of the counter-ion or solvents influence strongly the polybutadiene microstructure, a summary of all anionic or related strategies is proposed in this review to tune polybutadiene microstructures. The influence of alkali metals, alkaline earth metals and multi-metallic compounds as well as their environment is discussed.

Thermoplastic Elastomers via Combined Crystallization and Vitrification from Homogeneous Melts

Block copolymers with crystalline, glassy, and rubbery blocks were synthesized by anionic polymerization of butadiene, styrene, and isoprene followed by chlorosilane coupling and hydrogenation. The performance of two pentablock copolymers, with the block sequence crystalline–glassy–rubbery–glassy–crystalline, as thermoplastic elastomers (TPEs) was evaluated against triblock copolymers having either crystalline or glassy end blocks. Judicious choices of block lengths yielded homogeneous melts for both pentablocks; consequently, the low-shear-rate viscosities of the pentablocks were more than 2 orders of magnitude lower than that of the glassy–rubbery–glassy triblock, which remained microphase-separated in the melt. In the pentablocks, physical cross-linking was achieved by crystallization of the end blocks followed by vitrification of the adjacent glassy blocks, forming composite crystalline–glassy hard domains. All of the polymers studied exhibited desirable mechanical behavior for TPEs, including low You...

High‐Temperature Solvent Gradient Liquid Chromatography of Model Long Chain Branched Polyethylenes

SummaryThe high‐temperature solvent gradient liquid chromatography system 1‐decanol/1,2,4‐trichlorobenzene/porous graphite HypercarbTM has been applied to the separation of well‐defined model long chain branched (LCB) polyethylenes with different architectures (star, H‐type, super H‐type, pompom, comb). The model LCB polyethylenes have been prepared by anionic polymerization of butadiene followed by click chemistry. After hydrogenation of the polybutadienes, the LCB samples contain ∼ 2 mol % ethyl branches randomly distributed along the backbone and the LCB, as is typical for linear low density polyethylene (LLDPE). The results indicate that the LCB does not influence the chromatographic separation substantially. The adsorption characteristics of the LCB copolymers are dominated by the SCB content. The presence of LCB increases the molar mass of the samples; however, the increase in molar mass from 100 kg/mol to 200 kg/mol does not influence chromatographic separations in the applied system of porous carbon and 1‐decanol/1,2,4‐trichlorobenzene.

Amphiphilic Block Copolymer Containing Quaternary Ammonium Cation for Anion Exchange Membrane

Amphiphilic block copolymers are excellent materials for potential alkaline anion exchange membrane (AAEM) application. In this study, a new synthetic pathway was investigated for copolymerization of polybutadiene-b-poly(vinylbenzyl trimethyl ammonium chloride) (PB-b-P[VBTMA][Cl]). This amphiphilic diblock copolymer synthesis first involved formation of benzyloxyamine functionalized polybutadiene by using 2,2,6,6-tetramethyl-1-(2-bromo-1-phenylethoxy) piperidine to terminate living anionic polymerization of butadiene in cyclohexane at room temperature, and then the nitroxide-functionalized polybutadiene acted as a macroinitiator to polymerize vinylbenzyl chloride (VBC) by nitroxide mediate polymerization at 125°C in the bulk. Polybutadiene-b-pol(vinylbenzyl chloride) (PB-b-PVBC) was sequentially quaternized by trimethylamine gas in chloroform. Gel permeation chromatography (GPC) clearly showed the increase in molecular weight of PB-b-PVBC diblock copolymer, and the PB-b-PVBC was also characterized by the 1H NMR spectroscopy. Infrared spectroscopy confirmed the formation of quaternary ammonium cation. Finally, PB-b-P[VBTMA][Cl] was solvent cast in a chloroform/methanol co-solvent mixture, this solvent processability extend utility of PB-b-P[VBTMA][Cl] in AAEM application.

Synthesis and Applications of Chain End Functionalized Polyolefins

Chain end functionalized polyolefins( Cef-POs) are of great importance in macromolecular design and polyolefin modifications. By utilizing self-induced chain transfer reactions( to β-H,e. g.) or using chain transfer agents such as borane, phosphine and styrene( and its derivatives) / H 2 in olefin coordination polymerization,unsaturated bond and reactive group terminated polyolefins can be obtained,respectively. Successive chemical modification of chain-end group results in various Cef-POs. Given the status of "one polymer chain per catalyst"in living coordination polymerization of olefin,Cef-POs can also be obtained by endcapping living chains and / or applying functionalized living catalysts. The problem of low catalyst efficiency encountered in living coordination polymerization can be w ell solved by coordinative chain transfer polymerization( CCTP),a process involving rapid and reversible chain transfer reactions betw een the catalyst( active species) and the chain transfer agent( usually in the form of a main group metal alkyl). CCTP generates polyolefin capped by carbon-metal bond,w hich is highly reactive and can be modified into versatile terminal groups. In addition,living polymerization of Ylides,living anionic polymerization of butadiene and ring-opening metathesis polymerization of cycloolefine are alternative approaches to synthesize( analogues of) Cef-PEs. The applications of Cef-POs,featured by transformation reaction from metallocene to other polymerization( living anionic polymerization,"controlled / living " radical polymerization,ring-opening polymerization,etc.) and combination w ith click chemistry,include tw o main aspects: polymer modification and synthesis of topological polymer.

Investigations on the anionic polymerization of butadiene in capillaries by kinetic measurements and reactor simulation

For the first time the anionic polymerization of 1,3-butadiene (Bd) is successfully transferred from semi-batch into a continuous microfluidic setup with comparable product properties. The molecular weight distribution described by the polydispersity index (PDI) is commonly used as a key criterion for product quality. The steady state and the local resolution of a continuous setup provide the opportunity to investigate the progress of the PDI during anionic polymerization. In this work, the influence of kinetics (statistics) and fluid dynamics (FD) on the PDI of the product is investigated. Therefore a dedicated setup was designed and erected to keep Bd in the liquid phase and provide a pulsation free constant liquid flow. With optimized parameter settings, a separation of initiation and propagation is obtained and the intrinsic kinetics of propagation are determined. To explain the experimental results, an ideal plug flow and an ideal laminar flow model are applied and compared to computational fluid dynamics (CFD) simulations. Finally, it is concluded which FD and statistical contributions lead to the very low PDI of 1.04 found in the experiments.

AKTIVASI LITIUM SEBAGAI KATALISATOR PADA REAKSI PEMBENTUKAN HTPB

HTPB usually used as propellant fuel binder. This paper studied anionic polymerization of butadiene to form HTPB (Hydroxy Terminated Polybutadiene) with litium as catalyst. In practice, litium must be reactivated to remove antioxidant that surround it. Butadiene is polymerized in a 250 mL autoklave at room temperature and free oxygen. Litium was reactivated by melting and deforming. The polymer form was terminated by ethylene oxide to form HTPB. After it was washed by benzene and aquadest, HTPB structure was analyzed with FTIR at 910 cm and 970 cm. Investigation of the polymerization could produced HTPB if litium as catalyst was reactivated. HTPB resulted contain maximum 30 percent structure cis-1,4 HTPB. The average molecule weight can be control very well based on amount of litium (catalyst).

Synthesis of hydroxyl-terminated polybutadiene possessing high content of 1,4-units via anionic polymerization

The hydroxyl-terminated polybutadiene (HTPB) possessing high content of 1,4-units was synthesized by anionic polymerization of butadiene, using alkyllithium containing silicon-protected hydroxyl group as initiator and cyclohexane as solvent. The polymers were characterized by GPC, IR and 1H-NMR. The mechanical properties of cured films were also evaluated. The results show that the content of 1,4-units for HTPBs made by anionic polymerization reaches up to 90%. The molecular weight distribution is very narrow (≤ 1.05). The functionality of hydroxyl groups approaches 2. Compared with free radical HTPB, the elongation at break of anionic HTPB films increased by 70%, while the tensile strength remained nearly unchanged. This new HTPB can be very useful in solid propellant.

Molecular structure of polybutadienes synthesized with a lithium-containing initiation system

With the use of high-resolution NMR spectroscopy (600 MHz) and gel-permeation chromatography, the products of anionic polymerization of butadiene initiated by n-butyllithium modified with sodium and magnesium alcoholates are studied. It is shown that a change in synthesis conditions makes it possible to vary the configuration and isomeric composition and molecular parameters of polybutadienes. The distribution of 1,2-, cis-1,4-, and trans-1,4-units in a chain has a pronounced statistical character and depends on the composition of the initiation system.

SYNTHESIS OF POLYBUTADIENE-<I>b</I>-POLY[2-(DIMETHYLAMINO)ETHYL METHACRYLATE] AMPHIPHILIC BLOCK COPOLYMER BY MECHANISM TRANSFORMATION

A amphiphilic block copolymer of polybutadiene((PB)-b-poly[2-(dimethylamino))ethyl methacrylate](PDMAEMA) was synthesized by transformation of living anionic polymerization into atom transfer radical polymerization(ATRP).The macroinitiator,PB containing the 2-bromoisobutyryl end group(PB-Br) was attempted by anionic polymerization of butadiene with butyllithium initiator,then the living PB was chain extended with propylene oxide(PO) and terminated by 2-bromoisobutyryl bromide(BriBBr).By using PB-Br with controlled molecular weight(M_(n) = 5.7×10~(3)),high bromine content(the bromating efficiency,92.1%) and low polydispersity(M_(w)/M_(n) = 1.07) as macroinitiator and CuBr/N,N,N′,N″,N″-pentamethyldiethylenetriamine(PMDETA) as catalyst and ligand,ATRP of hydrophilic DMAEMA was realized at 50℃.Kinetics studies reveal a controlled/living polymerization for DMAEMA.The GPC curve of the diblock copolymer indicates a successful initiation and growth of the second block,showing a symmertrical peak due to the removal of uninitiated marcoinitiator.Microphase separation behavior of the diblock copolymer was studied by DSC technique.The properties of the PB-Br and amphiphilic block copolymer PB-b-PDMAEMA were characterized by()~1H-NMR,FTIR in detail.Polydispersity of the diblock copolymer remained low(M_(w)/M_(n)= 1.27) for ATRP of DMAEMA.Estimated by()~1H-NMR,the resulting copolymer was expressed as PB_((10))-b-PDMAEMA_((23)).The results show that well-defined target products with controlled molecular weight and low dispersity were obtained.

Synthesis and characterization of stereotriblock polybutadiene containing crystallizable high trans-1,4-polybutadiene block by barium salt of di(ethylene glycol) ethylether/triisobutylaluminium/dilithium

A series of high trans-1,4-low-cis-1,4-high trans-1,4-stereotriblock polybutadienes (HTPB-b-LCPB-b-HTPBs) were synthesized through a sequential anionic polymerization of butadiene (Bd) initiated by barium salt of di(ethylene glycol) ethylether/triisobutylaluminium/dilithium (BaDEGEE/TIBA/DLi). The polymers consisted of elastic low-cis-1,4-polybutadiene (LCPB) chemically bonded with crystallizable high trans-1,4-polybutadiene (HTPB). The block ratios (HTPB:LCPB:HTPB) were designed at 25:50:25 (molar ratio) and finally determined by SEC. The microstructures and sequences of the specimens were investigated by FTIR and NMR. The resultant HTPB-b-LCPB-b-HTPBs consisted of LCPB block with 52.5% trans-1,4 content and HTPB block with 55.9–85.8% trans-1,4 content. According to differential scanning calorimetry (DSC), HTPB-b-LCPB-b-HTPB showed a significant cold crystallization which was discussed in terms of entanglement concept. The cold crystallization temperature (Tcc) decreased whereas the melting temperature (Tm) increased with the increasing trans-1,4 content of HTPB block.