Molar mass effects in reversed-phase gradient polymer-elution chromatography of oligomers

Abstract

The dependence on molar mass of the retention of ohgomers in reversed-phase gradient polymer-elution chromatography (RP GPEC) has been investigated. To this end a variety of oligomer series, including polystyrene (PS) and amorphous polyesters (PE) were chromatographed using different non-solvent-solvent (NS-S) mobile phases and at different temperatures. Sigmoidally shaped curves were usually obtained for plots of amount (%) of S against 1/,,](molar mass) but the exact shape varied from almost linear to very convex. Increasing the temperature led to increased dependence of retention on the molar mass; this can be ascribed to a decrease in Flory-Huggins interaction parameters. Changing the NS-S system substantially affects the shape of the curves, but the effect is different for different oligomer series. From results from isocratic measurements for PS and a PE itwas found that the effect of experimental conditions can be ascribed to the relative contributions to retention of both end groups and of the monomer repeat units. Because these contributions are affected to different extents by chromatographic conditions, changing these conditions also affects the shape of the plot of the amount of S against 1/,](molar mass).

Methacrylic Stereoblock Copolymers via the Combination of Catalytic Chain Transfer and Anionic Polymerization

“…By using an analytical technique which separates based on chemical composition as opposed to hydrodynamic volume, it was possible to distinguish between the two homopolymers (pBzMA 6 and pMMA) and the block copolymer p(BzMA 6 - b -MMA x ) (Figure ). The observed oligomeric distribution of the macromonomer has been reported before in the literature . It is obvious that the resultant product contains both unreacted pBzMA 6 macromonomer and pMMA homopolymer (13–28 and 37–38 min, respectively), but a broad third peak corresponding to a copolymer can also be seen, spanning between the two homopolymers.…”

“…The observed oligomeric distribution of the macromonomer has been reported before in the literature. 64 It is obvious that the resultant product contains both unreacted pBzMA 6 macromonomer and pMMA homopolymer (13À28 and 37À38 min, respectively), but a broad third peak corresponding to a copolymer can also be seen, spanning between the two homopolymers. The broadness is as expected because the polymer consists of a variety of block sizes originating mainly from the macroinitiator pBzMA 6 and also somewhat from the second block.…”

Methacrylic Stereoblock Copolymers via the Combination of Catalytic Chain Transfer and Anionic Polymerization

“…By using an analytical technique which separates based on chemical composition as opposed to hydrodynamic volume, it was possible to distinguish between the two homopolymers (pBzMA 6 and pMMA) and the block copolymer p(BzMA 6 - b -MMA x ) (Figure ). The observed oligomeric distribution of the macromonomer has been reported before in the literature . It is obvious that the resultant product contains both unreacted pBzMA 6 macromonomer and pMMA homopolymer (13–28 and 37–38 min, respectively), but a broad third peak corresponding to a copolymer can also be seen, spanning between the two homopolymers.…”

“…The observed oligomeric distribution of the macromonomer has been reported before in the literature. 64 It is obvious that the resultant product contains both unreacted pBzMA 6 macromonomer and pMMA homopolymer (13À28 and 37À38 min, respectively), but a broad third peak corresponding to a copolymer can also be seen, spanning between the two homopolymers. The broadness is as expected because the polymer consists of a variety of block sizes originating mainly from the macroinitiator pBzMA 6 and also somewhat from the second block.…”

A New Methodology for the Synthesis of Fluorinated exo‐Glycals and Their Time‐Dependent Inhibition of UDP‐Galactopyranose Mutase

“…Therefore, liquid chromatography at critical conditions (LCCC) is a more suitable technique, separating homologues based on one comonomer, and being independent of the other comonomer 2, 5, 11–13. The development of LCCC can be seen as a result of intensive studies of (reversed‐phase) LC with gradient elution, which may be used for further polymer separation, yielding chromatographic resolution based on complete chemical composition 2, 5, 14–21. Even more enhanced separation is obtained by means of two‐dimensional chromatographic techniques 22–24.…”

Characterization of the chemical composition of a block copolymer by liquid chromatography/mass spectrometry using atmospheric pressure chemical ionization and electrospray ionization

“…2,5,[11][12][13] The development of LCCC can be seen as a result of intensive studies of (reversed-phase) LC with gradient elution, which may be used for further polymer separation, yielding chromatographic resolution based on complete chemical composition. 2,5,[14][15][16][17][18][19][20][21] Even more enhanced separation is obtained by means of two-dimensional chromatographic techniques. [22][23][24] LC in general is mostly used for the determination of the compositional distribution of functional end groups and the polymer backbone of addition polymers.…”

Methacrylic Stereoblock Copolymers via the Combination of Catalytic Chain Transfer and Anionic Polymerization

“…By using an analytical technique which separates based on chemical composition as opposed to hydrodynamic volume, it was possible to distinguish between the two homopolymers (pBzMA 6 and pMMA) and the block copolymer p(BzMA 6 - b -MMA x ) (Figure ). The observed oligomeric distribution of the macromonomer has been reported before in the literature . It is obvious that the resultant product contains both unreacted pBzMA 6 macromonomer and pMMA homopolymer (13–28 and 37–38 min, respectively), but a broad third peak corresponding to a copolymer can also be seen, spanning between the two homopolymers.…”

“…The observed oligomeric distribution of the macromonomer has been reported before in the literature. 64 It is obvious that the resultant product contains both unreacted pBzMA 6 macromonomer and pMMA homopolymer (13À28 and 37À38 min, respectively), but a broad third peak corresponding to a copolymer can also be seen, spanning between the two homopolymers. The broadness is as expected because the polymer consists of a variety of block sizes originating mainly from the macroinitiator pBzMA 6 and also somewhat from the second block.…”

A New Methodology for the Synthesis of Fluorinated exo‐Glycals and Their Time‐Dependent Inhibition of UDP‐Galactopyranose Mutase

“…Therefore, liquid chromatography at critical conditions (LCCC) is a more suitable technique, separating homologues based on one comonomer, and being independent of the other comonomer 2, 5, 11–13. The development of LCCC can be seen as a result of intensive studies of (reversed‐phase) LC with gradient elution, which may be used for further polymer separation, yielding chromatographic resolution based on complete chemical composition 2, 5, 14–21. Even more enhanced separation is obtained by means of two‐dimensional chromatographic techniques 22–24.…”

Characterization of the chemical composition of a block copolymer by liquid chromatography/mass spectrometry using atmospheric pressure chemical ionization and electrospray ionization

“…2,5,[11][12][13] The development of LCCC can be seen as a result of intensive studies of (reversed-phase) LC with gradient elution, which may be used for further polymer separation, yielding chromatographic resolution based on complete chemical composition. 2,5,[14][15][16][17][18][19][20][21] Even more enhanced separation is obtained by means of two-dimensional chromatographic techniques. [22][23][24] LC in general is mostly used for the determination of the compositional distribution of functional end groups and the polymer backbone of addition polymers.…”

Methacrylic Stereoblock Copolymers via the Combination of Catalytic Chain Transfer and Anionic Polymerization

“…By using an analytical technique which separates based on chemical composition as opposed to hydrodynamic volume, it was possible to distinguish between the two homopolymers (pBzMA 6 and pMMA) and the block copolymer p(BzMA 6 - b -MMA x ) (Figure ). The observed oligomeric distribution of the macromonomer has been reported before in the literature . It is obvious that the resultant product contains both unreacted pBzMA 6 macromonomer and pMMA homopolymer (13–28 and 37–38 min, respectively), but a broad third peak corresponding to a copolymer can also be seen, spanning between the two homopolymers.…”

“…The observed oligomeric distribution of the macromonomer has been reported before in the literature. 64 It is obvious that the resultant product contains both unreacted pBzMA 6 macromonomer and pMMA homopolymer (13À28 and 37À38 min, respectively), but a broad third peak corresponding to a copolymer can also be seen, spanning between the two homopolymers. The broadness is as expected because the polymer consists of a variety of block sizes originating mainly from the macroinitiator pBzMA 6 and also somewhat from the second block.…”

A New Methodology for the Synthesis of Fluorinated exo‐Glycals and Their Time‐Dependent Inhibition of UDP‐Galactopyranose Mutase

“…Therefore, liquid chromatography at critical conditions (LCCC) is a more suitable technique, separating homologues based on one comonomer, and being independent of the other comonomer 2, 5, 11–13. The development of LCCC can be seen as a result of intensive studies of (reversed‐phase) LC with gradient elution, which may be used for further polymer separation, yielding chromatographic resolution based on complete chemical composition 2, 5, 14–21. Even more enhanced separation is obtained by means of two‐dimensional chromatographic techniques 22–24.…”

Characterization of the chemical composition of a block copolymer by liquid chromatography/mass spectrometry using atmospheric pressure chemical ionization and electrospray ionization

“…2,5,[11][12][13] The development of LCCC can be seen as a result of intensive studies of (reversed-phase) LC with gradient elution, which may be used for further polymer separation, yielding chromatographic resolution based on complete chemical composition. 2,5,[14][15][16][17][18][19][20][21] Even more enhanced separation is obtained by means of two-dimensional chromatographic techniques. [22][23][24] LC in general is mostly used for the determination of the compositional distribution of functional end groups and the polymer backbone of addition polymers.…”