The Fractional Precipitation of Molecular-weight Species from High Polymers. Theories of the Process and Some Experimental Evidence.

Morey, D. R.; Tamblyn, J. W.

doi:10.1021/j150453a012

Cited by 38 publications

(10 citation statements)

References 13 publications

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“…The dispersities observed are uncharacteristically low (≤1.5) for polymers synthesized via step-growth processes, likely attributable to fractionation during polymer precipitation. 24 The 1 H NMR data for monomers 2a−c, shown in Figure 1, closely match those reported. 22 The resonances corresponding to the exo-propargyl ether methylenes (labeled y) in 2a and 2c appear as doublets (J = 2.4 Hz) at ca.…”

Section: Poly(2c)-[h]supporting

confidence: 84%

Synthesis of Isohexide Diyne Polymers and Hydrogenation to Their Saturated Polyethers

2021

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The incorporation of renewable feedstocks into polymer backbones is of great importance in modern polymer science. We report the synthesis of 1,3-diyne polymers derived from the bispropargyl ethers of isosorbide, isomannide, and isoidide. The dialkyne monomers can be polymerized through an adaptation of the Glaser−Hay coupling using a nickel(II) cocatalyst. These well-defined diyne polymers bear an iodoalkyne end group, afforded through an unanticipated reductive elimination pathway, and display glass transition temperatures (T g ) from 55 to 64 °C. Fully saturated, analogous polyethers can be prepared from the hydrogenation of the diyne polymers, and these show T g values between −10 and −2 °C. Both the 1,3-diyne polymers and the saturated analogues display similar trends in their T g values vis-a-vis the stereochemical features of the isohexide unit within the backbone. This polymerization provided access to two series of isohexide-based polyethers, the thermal properties of which are influenced by the nature of the 2,4-hexadiynyl and hexamethylene linkers as well as the relative configuration of the bicyclic subunit in the backbone. The reported method represents an important step toward accessing well-defined polyethers from renewable feedstocks using readily available catalysts and convenient ambient conditions.

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Section: Poly(2c)-[h]supporting

confidence: 84%

Synthesis of Isohexide Diyne Polymers and Hydrogenation to Their Saturated Polyethers

2021

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“…They concluded that "the effect of initial concentration on the efficiency of fractionation by precipitation is minor". The same conclusion was reached by Rehner (cited in Reference (17)) from his experience with fractionations of butyl rubber.…”

Section: Introductionsupporting

confidence: 75%

The Fractional Precipitation of Gr-S: The Effect of Concentration of the Solution on the Efficiency of Fractionation

Cragg¹,

Switzer²

1953

Can. J. Chem.

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A careful study was made of the fractionation of GR-S (commercial poly(butadiene-co-styrene)) by stepwise precipitation, from solution in benzene, with the precipitant 50: 50 (by volun~e) methanol-benzene. To deteimine the reproducibility of fractionation, particularly in the high-molecular-weight region, three runs were made with 2% solutions; and to determine the effect of concentration on efficiency, comparable fractionations were performed from. solutions of three different concentrations-1, 2, and 33 gm./100 ml. respectively. In each of the fractions the value of intrinsic viscosity, the viscosity slope constant 8, and the viscosity-average molecular weight were determined. These provide conclusive evidence that in such a primary fractionation a much cleaner separation is accon~plished from a dilute solution (1% or less).

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“…The molecular weight-dependent solubility of the polymers is well-known in the literature for a long time [ 24 ]. The phenomenon of longer chains of macromolecules being less soluble than the shorter ones of the analogous structure has been known for some time and has been utilized for the separation of chains on a length basis [ 25 ]. Since Schulz suggested that fractional precipitation is useful in investigating the molecular weight and its distribution, this fractionation method was applied extensively for molecular weight determination [ 26 ].…”

Section: Introductionmentioning

confidence: 99%

The Effect of Molecular Weight on the Solubility Properties of Biocompatible Poly(ethylene succinate) Polyester

et al. 2021

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Poly(ethylene succinate) (PES) is one of the most promising biodegradable and biocompatible polyesters and is widely used in different biomedical applications. However, little information is available on its solubility and precipitation properties, despite that these solution behavior properties affect its applicability. In order to systematically study these effects, biodegradable and biocompatible poly(ethylene succinate) (PES) was synthesized using ethylene glycol and succinic acid monomers with an equimolar ratio. Despite the optimized reaction temperature (T = 185 °C) of the direct condensation polymerization, relatively low molecular mass values were achieved without using a catalyst, and the Mn was adjustable with the reaction time (40–100 min) in the range of ~850 and ~1300 Da. The obtained crude products were purified by precipitation from THF (“good” solvent) with excess of methanol (“bad” solvent). The solvents for PES oligomers purification were chosen according to the calculated values of solubility parameters by different approaches (Fedors, Hoy and Hoftyzer-van Krevelen). The theta-solvent composition of the PES solution was 0.3 v/v% water and 0.7 v/v% DMSO in this binary mixture. These measurements were also allowed to determine important parameters such as the coefficients A (=0.67) and B (=3.69 × 104) from the Schultz equation, or the Kη (=8.22 × 10−2) and α (=0.52) constants from the Kuhn–Mark–Houwink equation. Hopefully, the prepared PES with different molecular weights is a promising candidate for biomedical applications and the reported data and constants are useful for other researchers who work with this promising polyester.

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The Fractional Precipitation of Molecular-weight Species from High Polymers. Theories of the Process and Some Experimental Evidence.

Cited by 38 publications

References 13 publications

Synthesis of Isohexide Diyne Polymers and Hydrogenation to Their Saturated Polyethers

Synthesis of Isohexide Diyne Polymers and Hydrogenation to Their Saturated Polyethers

The Fractional Precipitation of Gr-S: The Effect of Concentration of the Solution on the Efficiency of Fractionation

The Effect of Molecular Weight on the Solubility Properties of Biocompatible Poly(ethylene succinate) Polyester

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