Molecular Dimensions of Polydimethylsiloxanes<sup>1</sup>

Flory, Paul J.; Mandelkern, L.; Kinsinger, J. B.; Shultz, W. B.

doi:10.1021/ja01133a044

Cited by 121 publications

(39 citation statements)

References 2 publications

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“…5,1989 Pht are preferential solvents. The former is a poor solvent for PMMA and the latter is a poor solvent for PDMS (theta-temperature of Pht for PDMS is reported 83°C by Flory 38 and 89°C by Kuwahara 39 ). The segregation factor between MSt and PMMA is rather weak, while strong between MOMS and PMMA.…”

Section: Copolymerizationmentioning

confidence: 99%

Radical Copolymerization Behavior of Macromonomers; Incompatibility Effect

Tsukahara

Hayashi

Jiang

et al. 1989

Polym J

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ABSTRACT:Copolymerizations of methacrylate terminated styrene macromonomer (MSt, M.= 12400) and dimethylsiloxane macromonomers (MDMS, M.= 1020, 8670) with methyl methacrylate (MMA) were investigated in benzene (Bz), cyclohexane (Ch), and phenetol (Pht) to clarify the incompatibility effect between the macromonomer and the propagating comonomer chain on copolymerization behavior of the macromonomers. In the MSt/MMA/Bz copolymerization system i.e., copolymerization in mutual good solvent, it was observed that the relative copolymerization reactivity of macromonomer is almost the same as that of the small monomer corresponding to the polymerizable end group under homogeneous solution reaction conditions. On the other hand, in the MDMS/MMA/Bz copolymerization system, decrease in the reactivity of macromonomer was observed even under homogeneous solution conditions. These results were considered in terms of differences in the degree of interpenetration of unlike polymers in the reaction medium due to the different effects of incompatibility between the macro monomer and the propagating comonomer chain. Furthermore, in the case of copolymerizations in a preferential solvent, MSt/MMA/Ch and MDMS/MMA/Pht systems, the copolymerization system became heterogeneous as copolymerization proceeded and polymer particles of considerably uniform size were produced due to stabilization by the graft copolymers produced. In these cases, appreciable decrease in the relative copolymerization reactivity of macromonomer was observed due to much decrease in the interpenetration of unlike polymer species.

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Section: Copolymerizationmentioning

confidence: 99%

Radical Copolymerization Behavior of Macromonomers; Incompatibility Effect

Tsukahara

Hayashi

Jiang

et al. 1989

Polym J

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“…This finding is a further example for the principle inadequacy of theoretical concepts postulating that the second osmotic virial coefficient should inevitably become smaller with increasing chain length of the polymer. [3] It is worthwhile to note that the evaluation of the early osmotic pressure data reported [4] Figure 7, where all data fall on a common line.…”

Section: Quantitative Considerationsmentioning

confidence: 95%

“…Figure 5 shows the KuhnMark-Houwink relations for all solvents at 40 8C and that for the system MEK/PDMS also at 20 8C; furthermore it includes the information for the same system but at 30 8C reported in the literature. [4] The resulting parameters are collected in Table 2.…”

Section: Primary Datamentioning

confidence: 99%

“…coil according to Equation (4). To this end F o , the average volume fraction of polymer segments within an isolated coil, must be known.…”

Section: Dilution In Two Stepsmentioning

confidence: 99%

“…The polymer we have chosen for the measurements is poly(dimethylsiloxane) (PDMS). There are two reasons for this selection: The possibility to check the validity of the above-mentioned old literature data [4] and the fact that this polymer is liquid under ambient conditions and thus allows the determination of thermodynamic data in the entire range of composition. For theoretical reasons, [5] the molecular weight of the PDMS samples should be as large and the chemical difference between end groups and monomeric units as small as possible.…”

Section: Introductionmentioning

confidence: 99%

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Chain Connectivity and Conformational Variability of Polymers: Clues to an Adequate Thermodynamic Description of Their Solutions, 1

Bercea

Cazacu

Wolf

2003

Macro Chemistry & Physics

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This is the first of two parts investigating the Flory‐Huggins interaction parameter, χ, as a function of composition and chain length. Part 1 encompasses experimental and theoretical work. The former comprises the synthesis of poly(dimethylsiloxane)s with different molar mass and the measurements of their second osmotic virial coefficients, A2, in solvents of diverse quality as a function of M via light scattering and osmotic pressures. The theoretical analysis is performed by subdividing the dilution process into two clearly separable steps. It yields the following expression for χo, the χ value in range of pair interaction: χo = α − ζ λ. The parameter α measures the effect of contact formation between solvent molecules and polymer segments at fixed chain conformation, whereas the parameter ζ quantifies the contributions of the conformational changes taking place in response to dilution; ζ becomes zero for theta conditions. The influences of M are exclusively contained in the parameter λ The new relation is capable of describing hitherto incomprehensible experimental findings, like a diminution of χo with rising M. The evaluation of experimental information for different systems according to the established equation displays the existence of a linear interrelation between ζ and α. Part 2 of this investigation presents the generalization of the present approach to solutions of arbitrary composition and discusses the physical meaning of the parameters in more detail.

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Hyperbranched carbosilane oxazoline-macromonomers: polymerization and coupling to a trimesic acid core

Lach,

Hanselmann,

Frey

et al. 1998

Macromol. Rapid Commun.

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Attachment of oxazoline-based hyperbranched macromonomers to a trimesic acid core affording trimers of the hyperbranched fragments as well as polymerization of the oxazoline groups is reported. Polymerization and copolymerization with 2-phenyl-1,3-0xazoline were investigated for two macromonomers (aw = 1700 and 8000, respectively), resulting in hy~rbranched analogs of combburst polymers. Homopolymerization of the macromonomers yielded a degree of polymerization DP = 15. Hyperbranched trimers and the polyethyleneimines with apolar hyperbranched carbosilane side-chains form superstructures in solution and in bulk.

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Molecular Dimensions of Polydimethylsiloxanes¹

Cited by 121 publications

References 2 publications

Radical Copolymerization Behavior of Macromonomers; Incompatibility Effect

Radical Copolymerization Behavior of Macromonomers; Incompatibility Effect

Chain Connectivity and Conformational Variability of Polymers: Clues to an Adequate Thermodynamic Description of Their Solutions, 1

Hyperbranched carbosilane oxazoline-macromonomers: polymerization and coupling to a trimesic acid core

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Molecular Dimensions of Polydimethylsiloxanes1

Cited by 121 publications

References 2 publications

Radical Copolymerization Behavior of Macromonomers; Incompatibility Effect

Radical Copolymerization Behavior of Macromonomers; Incompatibility Effect

Chain Connectivity and Conformational Variability of Polymers: Clues to an Adequate Thermodynamic Description of Their Solutions, 1

Hyperbranched carbosilane oxazoline-macromonomers: polymerization and coupling to a trimesic acid core

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Molecular Dimensions of Polydimethylsiloxanes¹