Abstract Novel approaches to macroporous polymeric separation media with enhanced pore size distributions, controlled surface chemistries, and excellent separation properties have been explored. In the first of these approaches, size‐monodisperse spherical polymeric particles containing both large and small pores are prepared with the use of a variety of polymeric porogens. The choice of polymeric porogen as well as its concentration greatly affects the pore size and pore size distribution of the final beads. The polymer beads obtained by this technique have been tested in size exclusion chromatography and in the separation of proteins in reversed‐phase mode. Techniques that allow the specific functionalization of pores according to their sizes have been developed. Thus, the surfaces of the large pores of the monodisperse particles can be made hydrophilic or chiral while the smaller pores remain hydrophobic or achiral. Similarly, a novel polymeric separation medium based on a continuous polymer rod incorporating macropores has been prepared by an in situ polymerization within the confines of the tube of a chromatographic column. For example, non‐particulate continuous polymer rods with flow‐through pores as well as separation pores have been prepared from styrene and divinylbenzene and used in the very fast (30 s) separation of proteins by reversed‐phase chromatography. Alternatively, continuous rods prepared from glycidyl methacrylate and ethylene dimethacrylate can be transformed into materials that are suitable for ion exchange or other chromatographic modes. A characteristic of the continuous polymeric rod media is their permeability which allows the mobile phase to flow through the medium without causing a high back‐pressure. The continuous rod‐shaped media can also be modified in pore size‐selective fashion to introduce different chemistries in the large and the small pores. These new media are advantageous as they are extremely easy to prepare, durable, require no packing, and can be used for a variety of separations.
Many chemically amplified resists that function on the basis of acid catalysis of thermolytic reactions have been described as well as systems that function on the basis of free radical chain reactions. But there have been very few reports on the use of base catalysis of chemical transformations in resist materials. We describe here our initial results on base catalyzed chemically amplified deep-UV photoresists. Photogenerated amines were used as catalysts for the decarboxylation of carboxylic acids. Two approaches to building resists around this chemistry were investigated. (1) Decarboxylation of a low molecular weight carboxylic acid led to base induced dissolution inhibition of a phenolic polymer giving negative tone images. (2) A carboxylic acid polymer was synthesized which also is susceptible towards base catalyzed decarboxylation. Wet development of this resist material gives negative tone images. Site specific gas-phase silylation of the carboxylic acid allows the use of this material in a positive tone dry develop process. A 0.5 micrometers line-space pattern obtained by this dry develop process illustrates the potential of base-catalyzed chemical amplification.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPolymeric reagents. 3. Poly[vinyl(pyridinium chlorochromate)]: a new recyclable oxidizing agentJean M. J. Frechet, James Warnock, and M. Jean FarrallCite this: J. Org. Chem. 1978, 43, 13, 2618–2621Publication Date (Print):June 1, 1978Publication History Published online1 May 2002Published inissue 1 June 1978https://pubs.acs.org/doi/10.1021/jo00407a014https://doi.org/10.1021/jo00407a014research-articleACS PublicationsRequest reuse permissionsArticle Views471Altmetric-Citations102LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTUse of polymers as protecting groups in organic synthesis. Application of polystyrylboronic acid to the one-pot synthesis of acylated carbohydrate derivativesJean M. J. Frechet, Lucy J. Nuyens, and Elizabeth SeymourCite this: J. Am. Chem. Soc. 1979, 101, 2, 432–436Publication Date (Print):January 1, 1979Publication History Published online1 May 2002Published inissue 1 January 1979https://doi.org/10.1021/ja00496a027Request reuse permissionsArticle Views468Altmetric-Citations49LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (741 KB) Get e-Alertsclose Get e-Alerts
Read moreADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTChemical synthesis and structure proof of a stereoregular linear mannan, poly[.alpha.-(1->6')-anhydro-D-mannopyranose]Jean Frechet and Conrad SchuerchCite this: J. Am. Chem. Soc. 1969, 91, 5, 1161–1164Publication Date (Print):February 1, 1969Publication History Published online1 May 2002Published inissue 1 February 1969https://pubs.acs.org/doi/10.1021/ja01033a021https://doi.org/10.1021/ja01033a021research-articleACS PublicationsRequest reuse permissionsArticle Views199Altmetric-Citations59LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
Read moreADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhysical properties of dendritic macromolecules: a study of glass transition temperatureK. L. Wooley, C. J. Hawker, J. M. Pochan, and J. M. J. FrechetCite this: Macromolecules 1993, 26, 7, 1514–1519Publication Date (Print):March 1, 1993Publication History Published online1 May 2002Published inissue 1 March 1993https://pubs.acs.org/doi/10.1021/ma00059a006https://doi.org/10.1021/ma00059a006research-articleACS PublicationsRequest reuse permissionsArticle Views1478Altmetric-Citations284LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
Read moreThe synthesis of dendritic polyether macromolecules based on a 3, 5-dihydroxybenzyl alcohol building block and having carboxylate groups as chain-ends is described. These novel macromolecules behave as unimolecular micelles and their ability to solvate hydrophobic molecules has been investigated by UV–VIS spectroscopy. A dramatic increase in the saturation concentration of various polycyclic aromatic compounds in water was observed which was of a magnitude similar to that observed for micelles derived from sodium dodecyl sulfate. A relationship between the solubilizing power of the dendrimer and the electron density of the polycyclic aromatic was found. A linear relationship between the solubilizing ability and the concentration of the dendrimer, even at concentrations as low as 5 × 10–7 mol dm–3, indicates that these materials do not have a critical micelle concentration. Increases in the ionic strength of an aqueous solution of the dendrimer caused an increase in the saturation concentration of the hydrophobic molecules. A recyclable solubilization and extraction system is discussed. The synthesis of a globular dendritic macromolecular amphiphile designed to reside at the interface of an organic solvent and water is also described. This 'hybrid' dendritic amphiphile consisting of two distinct sectors, one hydrophilic and the other hydrophobic is prepared by stepwise alkylation of a core molecule, 4,4′-dihydroxybiphenyl with the two dissimilar dendritic fragments.
Read moreADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis and characterization of hyperbranched polyurethanes prepared from blocked isocyanate monomers by step-growth polymerizationRalph Spindler and Jean M. J. FrechetCite this: Macromolecules 1993, 26, 18, 4809–4813Publication Date (Print):August 1, 1993Publication History Published online1 May 2002Published inissue 1 August 1993https://pubs.acs.org/doi/10.1021/ma00070a013https://doi.org/10.1021/ma00070a013research-articleACS PublicationsRequest reuse permissionsArticle Views2293Altmetric-Citations162LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
Read moreAbstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Read more2,3,4,6-Tetra-O-benzyl-α-D-glucopyranosyl bromide (1) and, in one instance, its α-D-galacto isomer (2) were condensed under conditions of the Heiferich modification of the Koenigs–Knorr reaction with the four stereoisomeric methyl 4,6-O-benzylidene-3-deoxy-3-nitrohexopyranosides having the α-D-galacto (3), β-D-galacto (4), α-D-gluco (5), and β-D-gluco (6) configurations. Six new, 1 → 2 linked, fully blocked nitro disaccharides (7–12) were isolated. The configurations of the disaccharidic linkages were established by n.m.r. spectroscopy to be α in four of the products (8, 9, 11, and 12) and β in two (7 and 10). The steric course of the disaccharide bond formation was found to depend on the anomeric as well as the over-all configuration of the alcoholic components 3–6.
Read moreTwo types of insoluble polystyrene resins bearing vinylbenzaldehyde units have been prepared and used with high efficiency as temporary protecting groups in the synthesis of 2,3 disubstituted derivatives of methyl α-D-glucopyranoside.
Read moreAbstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Read moreADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEnantioselective addition of diethylzinc to aldehydes catalyzed by polymer-supported chiral amino alcohols. Evidence for a two zinc species mechanismShinichi Itsuno and Jean M. J. FrechetCite this: J. Org. Chem. 1987, 52, 18, 4140–4142Publication Date (Print):September 1, 1987Publication History Published online1 May 2002Published inissue 1 September 1987https://pubs.acs.org/doi/10.1021/jo00227a043https://doi.org/10.1021/jo00227a043research-articleACS PublicationsRequest reuse permissionsArticle Views656Altmetric-Citations131LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
Read moreADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhoto-crosslinking of a polyurethane with pendant methacryloyl-Terminated 4-Alkoxy-4'-sulfamoylstilbene NLO ChromophoresJody E Beecher, Tony Durst, Jean M. J. Frechet, Adelheid Godt, and Craig S. WillandCite this: Macromolecules 1994, 27, 13, 3472–3477Publication Date (Print):June 1, 1994Publication History Published online1 May 2002Published inissue 1 June 1994https://pubs.acs.org/doi/10.1021/ma00091a005https://doi.org/10.1021/ma00091a005research-articleACS PublicationsRequest reuse permissionsArticle Views243Altmetric-Citations16LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
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