Star-Branched Polymers. 2. The Reaction of Dienyllithium Chains with the Isomers of Divinylbenzene

Young, R. N.; Fetters, Lewis J.

doi:10.1021/ma60065a011

Cited by 60 publications

(22 citation statements)

References 7 publications

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“…The aggregates could represent some small amount of branched structures originating from side reaction of the living chain end with the side chain vinyl double bonds during synthesis. 12 Again in order to qualitatively visualize the build up of intensity with decreasing temperature, Figure 7 presents the cross section at Q ) 5 × 10 -3 Å -1 as a function of temperature. Due to the presence of a small amount of polymer clusters even at the highest temperature, the observed intensity is higher than the single coil scattering.…”

Section: S(q)mentioning

confidence: 99%

Self-Assembling Behavior in Decane Solution of Potential Wax Crystal Nucleators Based on Poly(co-olefins)

Schwahn¹,

Richter²,

Wright³

et al. 2002

Macromolecules

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The control of the precipitation and gelation of long chain paraffins from oil remains an enduring technological challenge regarding the processing and recovery of refined fuels and waxy crudes. Wax crystal modifiers based on polyethylene-poly(ethylene-propylene) (PE-PEP) diblock copolymers function as efficient nucleators for wax crystals in middle distillate fuels. These diblock polymers selfassemble in oil to form expansive platelike aggregates consisting of a PE core cloaked behind the amorphous PEP brush layer. The PE core thus promotes nucleation of solubilized long chain alkanes. Additional candidate structures for wax crystal nucleators include linear and star copolyolefins where the composition variation signals the alteration between crystalline and amorphous segments. This study focuses upon the self-assembling behavior in solution of these materials. The characteristics of the single chains and the aggregates formed at lower temperatures were determined via small-angle neutron scattering. Both plates and needlelike structures were found. The placement of the amorphous and crystalline blocks in the arms of the star shaped polymers was found to influence the architecture of the self-assembled micelles. As a point of comparison a commercial copolymer of ethylene-vinyl acetate (EVA) was also investigated. The EVA material was found to be relatively "undisciplined" in comparison to the structurally more uniform anionically prepared counterparts.

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Section: S(q)mentioning

confidence: 99%

Self-Assembling Behavior in Decane Solution of Potential Wax Crystal Nucleators Based on Poly(co-olefins)

Schwahn¹,

Richter²,

Wright³

et al. 2002

Macromolecules

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“…Furthermore, the coexistence of DVB isomers also caused a drop in linking efficiency; p-DVB links less efficiently than m-DVB. 18 At the optimum linking temperature of 60°C and [THF]/[n-BuLi]ϭ1.12, polymeric arms having three different arm lengths of 26400 Ϯ 6% (group A), 57200 Ϯ 4% (group B), and 120000Ϯ3% (group C) were used to synthesize the targeted starshaped molecules. The linking reaction was conducted at various DVB/n-BuLi molar ratios, namely 3, 6, and 9.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of a star‐shaped poly(ethylene‐co‐propylene) copolymer as a viscosity index improver for lubricants

Liou

Tsiang

Wu³

et al. 2001

J of Applied Polymer Sci

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ABSTRACT:A saturated star-shaped poly(ethylene-co-propylene) copolymer, (EP) star , has been synthesized for use as a viscosity index improver in lubricants. Polyisoprene arms were first anionically synthesized using n-butyllithium as the initiator, followed by a linking reaction with divinylbenzene at the optimum temperature of 60°C. The resulting star-shaped polyisoprene, (I) star , was then hydrogenated to eliminate the double bonds of the polyisoprene forming the poly(ethylene-co-propylene) structure. The degree of branching (number of arms on each molecule) increases with increase in the mole ratio of divinylbenzene to n-butyllithium. Increasing the arm length adversely affects the linking efficiency and a minimum amount of tetrahydrofuran (THF) at a THF:n-butyllithium molar ratio of 1.12 was needed in order to achieve a maximum linking efficiency of approximately 85%. The T g of poly(ethylene-co-propylene) is about 10°C higher than that of the original polyisoprene. Compared with (I) star , (EP) star has a thermal decomposition temperature that is 50°C higher but is independent of the arm length or the degree of branching. Viscosity measurement results for (EP) star reveal that intrinsic viscosity depends only on the arm length but not the degree of branching. Adding 1 wt % of (EP) star markedly increases the viscosity index of a LN base oil. The addition of 1 wt % of (EP) star increases the viscosity index (95 for base oil) up to a number between 111 and 145, with the exact number depending upon its arm length and degree of branching. With a fixed arm length, an (EP) star having a higher degree of branching increases the viscosity index more than one having a lower degree of branching. On the other hand, the viscosity index increases with increase in the arm length when the degree of branching is fixed. Adding 1 wt % of (EP) star also causes a change in the pour point of the lubricant with the pour point decreasing with increase in the degree of branching.

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“…Usually stars were formed with divinylbenzene (DVB) as crosslinking reagent: for example, in anionic polymerization of living polystyrene (PS), [1][2][3][4][5] polyisoprene (PI), [6][7][8][9] and polybutadiene (PB), 6,9 or in ATRP polymerization when as macroinitiators bromoisobutyryl derivatives of poly (e-caprolactone) 10 and poly(t-butylacrylate) 11,12 were used. Stars were obtained as well in anionic polymerization of poly(methyl methacrylate) with ethylene glycol dimethacrylate (EGDMA).…”

Section: Introductionmentioning

confidence: 99%

The influence of precursor's length and [diepoxide]_o/[MPEG]_o ratio on poly(ethylene glycol) star formation: The quantitative conversion of both precursors

Łapienis¹

2007

J. Polym. Sci. A Polym. Chem.

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Star-Branched Polymers. 2. The Reaction of Dienyllithium Chains with the Isomers of Divinylbenzene

Cited by 60 publications

References 7 publications

Self-Assembling Behavior in Decane Solution of Potential Wax Crystal Nucleators Based on Poly(co-olefins)

Self-Assembling Behavior in Decane Solution of Potential Wax Crystal Nucleators Based on Poly(co-olefins)

Synthesis of a star‐shaped poly(ethylene‐co‐propylene) copolymer as a viscosity index improver for lubricants

The influence of precursor's length and [diepoxide]_o/[MPEG]_o ratio on poly(ethylene glycol) star formation: The quantitative conversion of both precursors

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Star-Branched Polymers. 2. The Reaction of Dienyllithium Chains with the Isomers of Divinylbenzene

Cited by 60 publications

References 7 publications

Self-Assembling Behavior in Decane Solution of Potential Wax Crystal Nucleators Based on Poly(co-olefins)

Self-Assembling Behavior in Decane Solution of Potential Wax Crystal Nucleators Based on Poly(co-olefins)

Synthesis of a star‐shaped poly(ethylene‐co‐propylene) copolymer as a viscosity index improver for lubricants

The influence of precursor's length and [diepoxide]o/[MPEG]o ratio on poly(ethylene glycol) star formation: The quantitative conversion of both precursors

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The influence of precursor's length and [diepoxide]_o/[MPEG]_o ratio on poly(ethylene glycol) star formation: The quantitative conversion of both precursors