Abstract The preparation of monodisperse polymer particles formed by a dispersion copolymerization of a system containing styrene, butyl methacrylate, and nonpolymerizable dyes has been studied. Both the polarity of the ethanol–water dispersion medium and the polymerization rate were found to have a significant effect on the particle size. Experimental conditions have been determined that enable the preparation of colored beads having a narrow size distribution. While the benzoyl peroxide initiated polymerization is seriously inhibited by the presence of dyes, polymerization with azobisisobutyronitrile in presence of the black dye Nigrosin affords monodisperse beads in a high yield. © 1995 John Wiley & Sons, Inc.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNeutron Reflectivity and Structure of Polyether Dendrimers as Langmuir FilmsP. M. Saville, P. A. Reynolds, J. W. White, C. J. Hawker, J. M. J. Frechet, K. L. Wooley, J. Penfold, and J. R. P. WebsterCite this: J. Phys. Chem. 1995, 99, 20, 8283–8289Publication Date (Print):May 1, 1995Publication History Published online1 May 2002Published inissue 1 May 1995https://pubs.acs.org/doi/10.1021/j100020a062https://doi.org/10.1021/j100020a062research-articleACS PublicationsRequest reuse permissionsArticle Views280Altmetric-Citations97LEARN 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 options Get e-Alerts

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ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMolecular Ball Bearings: The Unusual Melt Viscosity Behavior of Dendritic MacromoleculesCraig J. Hawker, Peter J. Farrington, Michael E. Mackay, Karen L. Wooley, and Jean M. J. FrechetCite this: J. Am. Chem. Soc. 1995, 117, 15, 4409–4410Publication Date (Print):April 1, 1995Publication History Published online1 May 2002Published inissue 1 April 1995https://pubs.acs.org/doi/10.1021/ja00120a028https://doi.org/10.1021/ja00120a028research-articleACS PublicationsRequest reuse permissionsArticle Views782Altmetric-Citations206LEARN 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

Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry was utilized to study simple poly(ethylene glycol)s (PEG) and a series of amphiphilic copolymers prepared from PEG and dendritic molecules. For the amphiphilic copolymers with branched dendritic structures, MALDI-TOF spectrometry affords more accurate molecular weight data than the conventional gel-permeation chromatography (GPC). For mass lower than 10 000, the molecular weight distribution of the polymer is well-resolved into individual peaks. Using MALDI-TOF in the linear mode, copolymers with molecular masses of up to 43 000 Da were analyzed. For various dendrons attached to the same PEG, a good correlation was observed between calculated and measured data for the expected incremental increase as a function of dendrimer generation. End-group analysis using MALDI-TOF mass spectrometry proved very useful for the analysis of polymers with relatively low molecular weights. The experimental results agree well with the calculated masses of selected oligomers. Such end-group analysis can differentiate between the AB dendritic−linear diblocks, ABA triblocks, and linear PEG. These analyses support our earlier finding that the Williamson ether synthesis utilized in the PEG−dendron coupling reaction indeed converts all of the PEG to the desired block copolymer products.

Previously described dendritic and hyperbranched polyesters and a new linear polyester obtained by polymerization of 3-hydroxy-5-(t-butyldimethylsilyloxy)benzoic acid, each based on the 3,5-dihydroxybenzoic acid building block, were used in the study of differences in chemical and physical properties between the three different polymer architectures. Comparison of the physical properties between the dendritic, hyperbranched and linear structures showed that thermal properties, such as glass transition temperature and thermogravimetric analysis, were independent of macromolecular architecture. However, the dendritic and hyperbranched materials demonstrated comparative solubilities which were much greater than that found for the linear polymer. Other differences were observed in chemical reactivities.

The purpose of the present work was to investigate a liquid chromatographic method for the measurement of relative hydrogen bond basicities of dilute species. This type of determination cannot be done with conventional reversed-phase liquid chromatography due to the silanophilic interactions of basic solutes with the silica packing material. The studies were done on a polymeric stationary phase with pendant phenol groups that act as powerful hydrogen bond donors. Solute retention was evaluated in terms of two hydrogen bond basicity scales, beta 2H and beta 2C, and a steric hindrance parameter, Es. beta 2H and beta 2C are basicity scales based on the free energy of forming 1:1 hydrogen bond complexes and the retention on a strong hydrogen bond donor gas chromatographic phase, respectively. The Es parameter characterizes the steric effect experienced by the solute acceptor site. It is shown that retention correlates very strongly with beta 2H and less strongly with beta 2C. The log k' values need only two descriptive parameters, i.e., beta 2H and Es, to give a good fit. As a whole, retention on the phenolic polymeric phase provides an efficient method for the measurement of relative hydrogen bond basicities.

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTProton-Transfer Polymerization: A New Approach to Hyperbranched PolymersHan-Ting Chang and Jean M. J. FréchetView Author Information Department of Chemistry, University of California Berkeley, California 94720-1460 Cite this: J. Am. Chem. Soc. 1999, 121, 10, 2313–2314Publication Date (Web):February 27, 1999Publication History Received2 November 1998Published online27 February 1999Published inissue 1 March 1999https://pubs.acs.org/doi/10.1021/ja983797rhttps://doi.org/10.1021/ja983797rrapid-communicationACS PublicationsCopyright © 1999 American Chemical SocietyRequest reuse permissionsArticle Views1488Altmetric-Citations109LEARN 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 SUBJECTS:Aromatic compounds,Ethers,Hydrocarbons,Monomers,Polymerization Get e-Alerts

Ultra-thin dendrimer films are effective resists for high-resolution lithography using a scanning probe. The authors describe dendritic monolayer formation via covalent attachment to a silicon wafer surface and the field-enhanced oxidation of the dendrimer monolayers using scanning probe lithography to create features with dimensions less than 60 nm. Poly-(benzyl ether) dendrimers, terminated with either benzyl or tert-butyldiphenylsilyl ether groups, were used because of their relative ease of preparation and derivatization.

Linear copolymers that have pendant coumarin-2 and coumarin-343 chromophores were prepared as analogues to previously synthesized light-harvesting dendrimers. The chromophore ratios within these polymers were maintained similar to those of the various generation dendrimers to investigate the effect of polymer architecture on the energy-transfer efficiency between the coumarin-2 donors and coumarin-343 acceptors. Both physical and photophysical properties of these polymers were analyzed and compared to those of the analogous dendrimers. Energy-transfer efficiencies were relatively high in the polymers; however, deleterious excimer formation between the coumarin-343 chromophores diminished the quantum yield of fluorescence of the polymers when compared to the analogous dendrimers. Overall, it was found that the ultimate performance of the dendritic light-harvesting antennae was superior to that of the polymeric analogues, but the polymers were more practical in terms of synthetic accessibility. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1366–1373, 2001