Structure/chain-flexibility relationships of polymers

Zhao-yu, XU; Hadjichristidis, N.; Fetters, Lewis J.; Mays, Jimmy W.

doi:10.1007/3-540-58704-7_1

Cited by 71 publications

(56 citation statements)

References 205 publications

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“…Since the number of chain entanglements are very limited in the MIM triblocks, the deformation stress is not dissipated by the central block, but directly transferred to the PMMA microdomains. M e for PIOA and for PnBA has been calculated from rheological measurements [27][28][29][30], on the basis of Eq. (3) ( Table 2):…”

Section: Stress-strain Behaviormentioning

confidence: 99%

Synthesis of poly(methyl methacrylate)-b-poly(n-butyl acrylate)-b-poly(methyl methacrylate) triblocks and their potential as thermoplastic elastomers

Tong

Jérôme

2000

Polymer

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A series of well defined poly(methyl methacrylate) (PMMA)-b-poly(n-butyl acrylate) (PnBA)-b-PMMA triblock copolymers (MnBM) has been synthesized by transalcoholysis of PMMA-b-poly(tert-butylacrylate) (PtBA)-b-PMMA precursors (MTM) by n-butanol. Phase separation is observed for all the investigated triblock copolymers, which contain PMMA outer blocks in the 5000-50 000 molecular weight (MW) range and PnBA inner blocks with MW in the 100 000-200 000 range. Although the ultimate tensile properties of these MnBM triblock copolymers are poor compared to traditional diene-based TPEs (SBS and SIS), they are much better than those ones reported for PMMA-b-poly(isooctyl acrylate) (PIOA)-b-PMMA triblocks (MIM). A reasonable explanation for this observation is found in the average molecular weight between chain entanglements (M e ) that has been estimated to be 28 000 for the central PnBA rubbery block, which is consistently much smaller than for PIOA (59 000) and substantially higher than M e for polybutadiene (1700) and polyisoprene (6100). The tensile behavior of MnBM copolymers cannot be fitted by either a simple elastomer model free from chain entanglements (suitable to MIM) or by a "filler" modified rubber model (suitable for diene-based TPEs), supporting the hypothesis that the mechanical properties of the investigated (meth)acrylate thermoplastic elastomers are significantly affected by any change in M e of the central acrylate block. Viscoelastic analysis shows that MnBM triblocks are of higher complex viscosity than the SBS and SIS analogs, leading to a shift in the order-disorder transition temperature to much higher temperature, unless the outer PMMA blocks are of very low molecular weight (5000).

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Section: Stress-strain Behaviormentioning

confidence: 99%

Synthesis of poly(methyl methacrylate)-b-poly(n-butyl acrylate)-b-poly(methyl methacrylate) triblocks and their potential as thermoplastic elastomers

Tong

Jérôme

2000

Polymer

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“…Strictly speaking, n ) M z /M o . The value of l estimated from five PEK-C samples is ∼2 nm for PEK-C in CHCl 3 at 25°C, which leads to a value of C ∞ ∼ 25, using the formula C ∞ ) (2l/l o ) -1, 22 where l o is the average bond length. Figure 2 shows a typical line-width distribution, G(Γ), of PEK-C in CHCl 3 at 25°C after the solution was clarified with a 0.22-µm filter.…”

Section: Resultsmentioning

confidence: 99%

Laser Light-Scattering Study of Novel Thermoplastics. 1. Phenolphthalein Poly(aryl ether ketone)

Siddiq

et al. 1996

Macromolecules

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Five different molecular weight phenolphthalein poly(aryl ether ketone) (PEK-C) fractions in CHCl3 were studied by static and dynamic laser light scattering (LLS). The dynamic LLS revealed that the PEK-C samples contain some large polymer clusters. These large clusters can be removed by filtering the solution with a 0.1-µm filter. We found that the persistence length of PEK-C in CHCl3 at 25°C is ∼2 nm and the Flory characteristic ratio, C∞, is ∼25. Our results showed that 〈Rg 2 〉z 1/2 ) (3.50 ( 0.20) × 10 -2 Mw 0.54(0.01 and 〈D〉 ) (2.37 ( 0.05) × 10 -4 Mw -0.55(0.01 , with 〈Rg 2 〉z 1/2 , Mw, and 〈D〉 being the z-average radius of gyration, the weight-average molecular weight, and the z-average translational diffusion coefficient, respectively. A combination of static and dynamic LLS results enabled us to determine D ) (2.20 ( 0.10) × 10 -4 M -0.555(0.015 , where D and M correspond to monodisperse species. Using this calibration between D and M, we have determined molecular weight distributions of five PEK-C fractions from their corresponding translational diffusion coefficient distribution.

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“…where M w is the average PS molecular weight, l o is the length of a CÀC bond (0.154 nm), m o is the molar mass per backbone bond (52 for PS), and C 1 is 10.5 at 20 to 25 C [24]. The predicted mole ratio producing t p equal to R g is 0.90 from the correlation line of Equation (3) and Figure 5.…”

Section: Role Of Silane In Determining Thickness Of Grafted Polystyrementioning

confidence: 98%

Fracture Toughness of a Silane Coupled Polymer-Metal Interface: Silane Concentration Effects

Berry

Namkanisorn

2005

The Journal of Adhesion

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Fracture toughness of joints made from a glassy, 343,000 molecular weight polystyrene block bonded to chromic-sulfuric acid etched or phosphoric acid anodized aluminum are investigated. The fracture tests are performed with a 90-degree peel apparatus under ''dry'' laboratory conditions and ''wet'' conditions created by submerging the apparatus in a temperature controlled water bath. The bond strengths are controlled using various concentrations of styrl silane coupling agent added directly into the styrene monomer solution that polymerizes against the aluminum. Ellipsometric measurements on smooth silicon surfaces verify that the thickness of bound polymer is controlled by the silane to polystyrene mole ratio. X-ray photoelectron spectroscopy (XPS) analysis of fractured surfaces indicates that the fracture is near the aluminum surface. Both the wet and dry fracture energy as a function of bound polymer thickness on acid etched aluminum joints resemble quite closely the adhesion literature results obtained by fracturing pairs of fused, immiscible glassy polymers. Reasons for this similarity are discussed.

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Structure/chain-flexibility relationships of polymers

Cited by 71 publications

References 205 publications

Synthesis of poly(methyl methacrylate)-b-poly(n-butyl acrylate)-b-poly(methyl methacrylate) triblocks and their potential as thermoplastic elastomers

Synthesis of poly(methyl methacrylate)-b-poly(n-butyl acrylate)-b-poly(methyl methacrylate) triblocks and their potential as thermoplastic elastomers

Laser Light-Scattering Study of Novel Thermoplastics. 1. Phenolphthalein Poly(aryl ether ketone)

Fracture Toughness of a Silane Coupled Polymer-Metal Interface: Silane Concentration Effects

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