Lewis Manring - Academia.edu (original) (raw)

Papers by Lewis Manring

Springer series in chemical physics, 1984

Recently there have appeared several reports of picosecond absorption studies for the photodissoc... more Recently there have appeared several reports of picosecond absorption studies for the photodissociation of triarylmethanes(1,2,3). This class of molecules is of interest as photoexcitation leads to the formation of ion pairs, the kinetics of which are highly solvent dependent. The 300 nm photolysis of malachite green leucocyanide (MGCN) results in the formation of malachite green cation (MG+) whose appearance, when monitored at 610 nm, is non-exponential. In order to develop a more comprehensive understanding of the molecular events that give rise to this behavior we have examined the picosecond absorption kinetics of a series of TAMs.

Macromolecules, Dec 1, 1989

L'incorporation de liaisons «tete a tete» dans une chaine de PMMA reduit la temperature de de... more L'incorporation de liaisons «tete a tete» dans une chaine de PMMA reduit la temperature de degradation en facilitant la rupture homolytique de la chaine. Lorsque le degre de polymerisation du polymere est superieur a 200, cet effet est reduit par la recombinaison de cage

Chemischer Informationsdienst, Sep 9, 1980

ChemInform Abstract Tetraphenylallen (I) reagiert bei der Photooxidationüber (II) zu den Folgepro... more ChemInform Abstract Tetraphenylallen (I) reagiert bei der Photooxidationüber (II) zu den Folgeprodukten Kohlensäure, Benzophenon (III) sowie dem Bis-hydroperoxid (IV); letzteres wird zu (V) reduziert und mit Schwefelsäure zum Ether (VI) cyclisiert. (Keine Ausbeuteangaben, Zwischenstufen, Mechanismen).

The Journal of Physical Chemistry, Aug 1, 1984

Chemischer Informationsdienst, Mar 26, 1985

ChemInform Abstract Durch ps-Absorptionsspektroskopie zwischen 360-835 nm nach Bestrahlung mit 53... more ChemInform Abstract Durch ps-Absorptionsspektroskopie zwischen 360-835 nm nach Bestrahlung mit 532 oder 355 nm wird festgestellt, dass I2 mit den Arenen [Ar] Benzol, Toluol und Mesitylen intermediäre Radikal-Ionenpaare [Ar+•/I2-•] bildet.

Journal of the American Chemical Society, Dec 1, 1984

I ' may recombine or undergo reorientation within the solvent cage to reform the EDA complex. We ... more I ' may recombine or undergo reorientation within the solvent cage to reform the EDA complex. We expect that the breaking of the Registry No.

Macromolecules, Feb 1, 1988

Macromolecules, May 1, 1991

It is proposed that a side-group scission of a methoxycarbonyl group initiates saturated-PMMA deg... more It is proposed that a side-group scission of a methoxycarbonyl group initiates saturated-PMMA degradation. Side-group scission is favored due to a large «cage» recombination effects which reduces the contribution of main-chain scission. It is anticipated that side-group scission will initiate polymer degradation whenever side-group bonds are of similar energy or weaker than main-chain bonds

Chemischer Informationsdienst, Jul 30, 1985

Macromolecules, Sep 1, 1992

The thermal degradation of poly(2,2-dialkyl-3-propiolactones) (I) has been studied. By comparing ... more The thermal degradation of poly(2,2-dialkyl-3-propiolactones) (I) has been studied. By comparing the thermal degradation of capped (methyl esterified) and uncapped (carboxylic acid terminated) polymer, it is demonstrated that above-350 "C, I degrades by unzipping from carboxylic acid termini. Random scissions can generate chains with carboxylic acid termini. Capped I requires random scission generation of carboxylic acid termini before polymer unzipping can ensue. One random scission process elucidated requires the presence of a C-H group at the 2 position of one of the alkyl side groups in I and generates two distinguishable chains. One of the chains has a carboxylic acid terminus that can unzip. The second chain is still capped and must undergo further random scissions before mass loss can occur.

Macromolecules, Jun 1, 1989

L'incorporation de liaisons «tete a tete» dans une chaine de PMMA reduit la temperature de de... more L'incorporation de liaisons «tete a tete» dans une chaine de PMMA reduit la temperature de degradation en facilitant la rupture homolytique de la chaine. Lorsque le degre de polymerisation du polymere est superieur a 200, cet effet est reduit par la recombinaison de cage

Chemischer Informationsdienst, Oct 9, 1984

ChemInform Abstract Die durch Dicyano-anthracen sensibilisierte Photooxidation von trans-Stilben ... more ChemInform Abstract Die durch Dicyano-anthracen sensibilisierte Photooxidation von trans-Stilben wird durch einen Zusatz von Benzochinon verlangsamt. (Zwischenstufen, Mechanismen).

Macromolecules, Apr 1, 1990

The thermal degradation of poly(2,2-dialkyl-3-propiolactones) (I) has been studied. By comparing ... more The thermal degradation of poly(2,2-dialkyl-3-propiolactones) (I) has been studied. By comparing the thermal degradation of capped (methyl esterified) and uncapped (carboxylic acid terminated) polymer, it is demonstrated that above-350 "C, I degrades by unzipping from carboxylic acid termini. Random scissions can generate chains with carboxylic acid termini. Capped I requires random scission generation of carboxylic acid termini before polymer unzipping can ensue. One random scission process elucidated requires the presence of a C-H group at the 2 position of one of the alkyl side groups in I and generates two distinguishable chains. One of the chains has a carboxylic acid terminus that can unzip. The second chain is still capped and must undergo further random scissions before mass loss can occur.

The Journal of Physical Chemistry, 1983

The interaction of a variety of substrates with the singlet excited states of 9-cyanoanthracene, ... more The interaction of a variety of substrates with the singlet excited states of 9-cyanoanthracene, 'CNA, and 9,10-dicyanoanthracene, 'DCA, leads to enhanced intersystem crossing (isc), as demonstrated by transient triplet-triplet (T-T) absorption spectra. The T-T spectra showed maximum absorptions at 427 and 440 nm for 3CNA and 3DCA, respectively. The relative amount of intersystem crossing, determined by the intensity of the transient, is substrate dependent. The enhanced intersystem crossing leads to increased formation of IO2 and is a major source of '02 in many cyanoaromatic-sensitized oxidations. Recently we have reported that the interaction of 302 with 'DCA ultimately produces 2 mol of 102.5 Again, when k,[S] >> k 4 [ 0 2 ] , step 4 will also form 3D inefficiently. In this paper, we present evidence that step 6 can form ' D and that this step can lead to significant '02 production.

Chemischer Informationsdienst, Mar 11, 1986

ChemInform Abstract Triplett-Benzophenon bildet mit dem Amin (II)über den Radikalionenkomplex (II... more ChemInform Abstract Triplett-Benzophenon bildet mit dem Amin (II)über den Radikalionenkomplex (III) nach vorangegangener Umorientierung innerhalb von (III) durch Protonentransfer die Radikale (IV) und (V). Das Absorptionsspektrum des Ketyls ist 40 ps nach der Anregung beobachtbar. Die ebenfalls mögliche Elektronen-Rückübertragung in (III) ist um mindestens l Grössenordnung langsamer als der exotherrne Protonentransfer, dessen Geschwindigkeit bei steigender Lösungsmittelpolarität abnimmt. (VI)überträgt Protonen aus der Methylgruppe auf Benzophenon, während beim Protonentransfer auf Anthrachinon auch 9-Methylen-protonen beteiligt sind. Für den Protonenübergang in (VII) wird nach intramolekularer Zwitterionbildung ein intermolekularer Prozess angenommen.

Chemischer Informationsdienst, Apr 30, 1985

ChemInform Abstract Durch ps-Absorptionsspektroskopie zwischen 360-835 nm nach Bestrahlung mit 53... more ChemInform Abstract Durch ps-Absorptionsspektroskopie zwischen 360-835 nm nach Bestrahlung mit 532 oder 355 nm wird festgestellt, dass I2 mit den Arenen [Ar] Benzol, Toluol und Mesitylen intermediäre Radikal-Ionenpaare [Ar+•/I2-•] bildet.

Angewandte Chemie International Edition

Although controlled radical polymerization is an excellent tool to make precision polymeric mater... more Although controlled radical polymerization is an excellent tool to make precision polymeric materials, reversal of the process to retrieve the starting monomer is far less explored despite the significance of chemical recycling. Here, we investigate the bulk depolymerization of RAFT and ATRP‐synthesized polymers under identical conditions. RAFT‐synthesized polymers undergo a relatively low‐temperature solvent‐free depolymerization back to monomer thanks to the partial in situ transformation of the RAFT end‐group to macromonomer. Instead, ATRP‐synthesized polymers can only depolymerize at significantly higher temperatures (>350 °C) through random backbone scission. To aid a more complete depolymerization at even lower temperatures, we performed a facile and quantitative end‐group modification strategy in which both ATRP and RAFT end‐groups were successfully converted to macromonomers. The macromonomers triggered a lower temperature bulk depolymerization with an onset at 150 °C yie...

Chemischer Informationsdienst, 1986

Metallized Plastics 1, 1989

Metal interlayer deposition comprises a new family of wet-chemical processes by which a dense, el... more Metal interlayer deposition comprises a new family of wet-chemical processes by which a dense, electrically continuous metal film can be grown within the bulk of a pre-existing polymer film. The present article reviews three generic forms of the process, namely: electroless, polymer-mediated electrochemical, and carrier-mediated electrochemical deposition. Experimental examples are given with particular emphasis on polyimides as the matrix material. Mechanistic principles which govern the kinetics and morphology of the deposition are described.

Although controlled radical polymerization is an excellent tool to make precision polymeric mater... more Although controlled radical polymerization is an excellent tool to make precision polymeric materials, reversal of the process to retrieve the starting monomer is far less explored despite the significance of chemical recycling. Current depolymerization approaches typically require elevated temperatures (>350 ˚C), high dilutions in specific solvents (typically 0.1-25 mM polymer concentrations), and/or expensive catalysts. Here, we report that RAFT-synthesized polymers can undergo a low-temperature solvent-free depolymerization back to monomer thanks to the partial in-situ transformation of the RAFT end-group to macromonomer. To aid a more complete depolymerization, we performed a facile and quantitative end-group modification strategy with the modified RAFT polymers exhibiting significantly higher depolymerization conversions (~90%) at comparable temperatures. The end-group transformation was applied to polymers synthesized by ATRP triggering an efficient low-temperature bulk dep...

Springer series in chemical physics, 1984

Recently there have appeared several reports of picosecond absorption studies for the photodissoc... more Recently there have appeared several reports of picosecond absorption studies for the photodissociation of triarylmethanes(1,2,3). This class of molecules is of interest as photoexcitation leads to the formation of ion pairs, the kinetics of which are highly solvent dependent. The 300 nm photolysis of malachite green leucocyanide (MGCN) results in the formation of malachite green cation (MG+) whose appearance, when monitored at 610 nm, is non-exponential. In order to develop a more comprehensive understanding of the molecular events that give rise to this behavior we have examined the picosecond absorption kinetics of a series of TAMs.

Macromolecules, Dec 1, 1989

L'incorporation de liaisons «tete a tete» dans une chaine de PMMA reduit la temperature de de... more L'incorporation de liaisons «tete a tete» dans une chaine de PMMA reduit la temperature de degradation en facilitant la rupture homolytique de la chaine. Lorsque le degre de polymerisation du polymere est superieur a 200, cet effet est reduit par la recombinaison de cage

Chemischer Informationsdienst, Sep 9, 1980

ChemInform Abstract Tetraphenylallen (I) reagiert bei der Photooxidationüber (II) zu den Folgepro... more ChemInform Abstract Tetraphenylallen (I) reagiert bei der Photooxidationüber (II) zu den Folgeprodukten Kohlensäure, Benzophenon (III) sowie dem Bis-hydroperoxid (IV); letzteres wird zu (V) reduziert und mit Schwefelsäure zum Ether (VI) cyclisiert. (Keine Ausbeuteangaben, Zwischenstufen, Mechanismen).

The Journal of Physical Chemistry, Aug 1, 1984

Chemischer Informationsdienst, Mar 26, 1985

ChemInform Abstract Durch ps-Absorptionsspektroskopie zwischen 360-835 nm nach Bestrahlung mit 53... more ChemInform Abstract Durch ps-Absorptionsspektroskopie zwischen 360-835 nm nach Bestrahlung mit 532 oder 355 nm wird festgestellt, dass I2 mit den Arenen [Ar] Benzol, Toluol und Mesitylen intermediäre Radikal-Ionenpaare [Ar+•/I2-•] bildet.

Journal of the American Chemical Society, Dec 1, 1984

I ' may recombine or undergo reorientation within the solvent cage to reform the EDA complex. We ... more I ' may recombine or undergo reorientation within the solvent cage to reform the EDA complex. We expect that the breaking of the Registry No.

Macromolecules, Feb 1, 1988

Macromolecules, May 1, 1991

It is proposed that a side-group scission of a methoxycarbonyl group initiates saturated-PMMA deg... more It is proposed that a side-group scission of a methoxycarbonyl group initiates saturated-PMMA degradation. Side-group scission is favored due to a large «cage» recombination effects which reduces the contribution of main-chain scission. It is anticipated that side-group scission will initiate polymer degradation whenever side-group bonds are of similar energy or weaker than main-chain bonds

Chemischer Informationsdienst, Jul 30, 1985

Macromolecules, Sep 1, 1992

The thermal degradation of poly(2,2-dialkyl-3-propiolactones) (I) has been studied. By comparing ... more The thermal degradation of poly(2,2-dialkyl-3-propiolactones) (I) has been studied. By comparing the thermal degradation of capped (methyl esterified) and uncapped (carboxylic acid terminated) polymer, it is demonstrated that above-350 "C, I degrades by unzipping from carboxylic acid termini. Random scissions can generate chains with carboxylic acid termini. Capped I requires random scission generation of carboxylic acid termini before polymer unzipping can ensue. One random scission process elucidated requires the presence of a C-H group at the 2 position of one of the alkyl side groups in I and generates two distinguishable chains. One of the chains has a carboxylic acid terminus that can unzip. The second chain is still capped and must undergo further random scissions before mass loss can occur.

Macromolecules, Jun 1, 1989

L'incorporation de liaisons «tete a tete» dans une chaine de PMMA reduit la temperature de de... more L'incorporation de liaisons «tete a tete» dans une chaine de PMMA reduit la temperature de degradation en facilitant la rupture homolytique de la chaine. Lorsque le degre de polymerisation du polymere est superieur a 200, cet effet est reduit par la recombinaison de cage

Chemischer Informationsdienst, Oct 9, 1984

ChemInform Abstract Die durch Dicyano-anthracen sensibilisierte Photooxidation von trans-Stilben ... more ChemInform Abstract Die durch Dicyano-anthracen sensibilisierte Photooxidation von trans-Stilben wird durch einen Zusatz von Benzochinon verlangsamt. (Zwischenstufen, Mechanismen).

Macromolecules, Apr 1, 1990

The thermal degradation of poly(2,2-dialkyl-3-propiolactones) (I) has been studied. By comparing ... more The thermal degradation of poly(2,2-dialkyl-3-propiolactones) (I) has been studied. By comparing the thermal degradation of capped (methyl esterified) and uncapped (carboxylic acid terminated) polymer, it is demonstrated that above-350 "C, I degrades by unzipping from carboxylic acid termini. Random scissions can generate chains with carboxylic acid termini. Capped I requires random scission generation of carboxylic acid termini before polymer unzipping can ensue. One random scission process elucidated requires the presence of a C-H group at the 2 position of one of the alkyl side groups in I and generates two distinguishable chains. One of the chains has a carboxylic acid terminus that can unzip. The second chain is still capped and must undergo further random scissions before mass loss can occur.

The Journal of Physical Chemistry, 1983

The interaction of a variety of substrates with the singlet excited states of 9-cyanoanthracene, ... more The interaction of a variety of substrates with the singlet excited states of 9-cyanoanthracene, 'CNA, and 9,10-dicyanoanthracene, 'DCA, leads to enhanced intersystem crossing (isc), as demonstrated by transient triplet-triplet (T-T) absorption spectra. The T-T spectra showed maximum absorptions at 427 and 440 nm for 3CNA and 3DCA, respectively. The relative amount of intersystem crossing, determined by the intensity of the transient, is substrate dependent. The enhanced intersystem crossing leads to increased formation of IO2 and is a major source of '02 in many cyanoaromatic-sensitized oxidations. Recently we have reported that the interaction of 302 with 'DCA ultimately produces 2 mol of 102.5 Again, when k,[S] >> k 4 [ 0 2 ] , step 4 will also form 3D inefficiently. In this paper, we present evidence that step 6 can form ' D and that this step can lead to significant '02 production.

Chemischer Informationsdienst, Mar 11, 1986

ChemInform Abstract Triplett-Benzophenon bildet mit dem Amin (II)über den Radikalionenkomplex (II... more ChemInform Abstract Triplett-Benzophenon bildet mit dem Amin (II)über den Radikalionenkomplex (III) nach vorangegangener Umorientierung innerhalb von (III) durch Protonentransfer die Radikale (IV) und (V). Das Absorptionsspektrum des Ketyls ist 40 ps nach der Anregung beobachtbar. Die ebenfalls mögliche Elektronen-Rückübertragung in (III) ist um mindestens l Grössenordnung langsamer als der exotherrne Protonentransfer, dessen Geschwindigkeit bei steigender Lösungsmittelpolarität abnimmt. (VI)überträgt Protonen aus der Methylgruppe auf Benzophenon, während beim Protonentransfer auf Anthrachinon auch 9-Methylen-protonen beteiligt sind. Für den Protonenübergang in (VII) wird nach intramolekularer Zwitterionbildung ein intermolekularer Prozess angenommen.

Chemischer Informationsdienst, Apr 30, 1985

ChemInform Abstract Durch ps-Absorptionsspektroskopie zwischen 360-835 nm nach Bestrahlung mit 53... more ChemInform Abstract Durch ps-Absorptionsspektroskopie zwischen 360-835 nm nach Bestrahlung mit 532 oder 355 nm wird festgestellt, dass I2 mit den Arenen [Ar] Benzol, Toluol und Mesitylen intermediäre Radikal-Ionenpaare [Ar+•/I2-•] bildet.

Angewandte Chemie International Edition

Although controlled radical polymerization is an excellent tool to make precision polymeric mater... more Although controlled radical polymerization is an excellent tool to make precision polymeric materials, reversal of the process to retrieve the starting monomer is far less explored despite the significance of chemical recycling. Here, we investigate the bulk depolymerization of RAFT and ATRP‐synthesized polymers under identical conditions. RAFT‐synthesized polymers undergo a relatively low‐temperature solvent‐free depolymerization back to monomer thanks to the partial in situ transformation of the RAFT end‐group to macromonomer. Instead, ATRP‐synthesized polymers can only depolymerize at significantly higher temperatures (>350 °C) through random backbone scission. To aid a more complete depolymerization at even lower temperatures, we performed a facile and quantitative end‐group modification strategy in which both ATRP and RAFT end‐groups were successfully converted to macromonomers. The macromonomers triggered a lower temperature bulk depolymerization with an onset at 150 °C yie...

Chemischer Informationsdienst, 1986

Metallized Plastics 1, 1989

Metal interlayer deposition comprises a new family of wet-chemical processes by which a dense, el... more Metal interlayer deposition comprises a new family of wet-chemical processes by which a dense, electrically continuous metal film can be grown within the bulk of a pre-existing polymer film. The present article reviews three generic forms of the process, namely: electroless, polymer-mediated electrochemical, and carrier-mediated electrochemical deposition. Experimental examples are given with particular emphasis on polyimides as the matrix material. Mechanistic principles which govern the kinetics and morphology of the deposition are described.

Although controlled radical polymerization is an excellent tool to make precision polymeric mater... more Although controlled radical polymerization is an excellent tool to make precision polymeric materials, reversal of the process to retrieve the starting monomer is far less explored despite the significance of chemical recycling. Current depolymerization approaches typically require elevated temperatures (>350 ˚C), high dilutions in specific solvents (typically 0.1-25 mM polymer concentrations), and/or expensive catalysts. Here, we report that RAFT-synthesized polymers can undergo a low-temperature solvent-free depolymerization back to monomer thanks to the partial in-situ transformation of the RAFT end-group to macromonomer. To aid a more complete depolymerization, we performed a facile and quantitative end-group modification strategy with the modified RAFT polymers exhibiting significantly higher depolymerization conversions (~90%) at comparable temperatures. The end-group transformation was applied to polymers synthesized by ATRP triggering an efficient low-temperature bulk dep...