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.

Abstract The divergent dendronization of an ϵ‐caprolactone‐based polymer has been performed to provide access to dendronized polymers with sufficient biocompatibility and degradability for use as drug‐delivery scaffolds. The synthesis was performed through the tin(II) 2‐ethylhexanoate‐catalyzed polymerization of a γ‐functionalized ϵ‐caprolactone monomer, followed by the divergent growth of pendant polyester dendrons at each repeat unit. The resulting dendronized polymers were obtained up to the fourth generation with molecular weights as high as 80,000 Da and with polydispersities between 1.11 and 1.22. The fourth‐generation hydroxyl‐terminated dendronized polymer was degradable under a variety of aqueous conditions. A comparison of the dendronization approach with a procedure involving the ring‐opening polymerization of a second‐generation dendritic macromonomer reveals that the former procedure is best suited for the preparation of this family of dendronized polyesters because it requires shorter reaction times and affords materials with higher degrees of polymerization. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3563–3578, 2004

In the area of crosslinked chemical supports, continuous media such as rigid macroporous polymer monoliths have certain advantages. Following an introduction to monolithic porous polymer materials, the various applications of macroporous polymer monoliths are reviewed. The Figure shows an SEM image of a monolith prepared within the confines of a polyimide-coated fused silica capillary.

ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTA New Approach to Hyperbranched Polymers by Ring-Opening Polymerization of an AB Monomer: 4-(2-Hydroxyethyl)-ε-caprolactoneMingjun Liu, Nikolay Vladimirov, and Jean M. J. FréchetView Author Information Department of Chemistry, University of California, Berkeley, California 94720-1460 Cite this: Macromolecules 1999, 32, 20, 6881–6884Publication Date (Web):September 15, 1999Publication History Received18 May 1999Revised19 August 1999Published online15 September 1999Published inissue 1 October 1999https://pubs.acs.org/doi/10.1021/ma990785xhttps://doi.org/10.1021/ma990785xrapid-communicationACS PublicationsCopyright © 1999 American Chemical SocietyRequest reuse permissionsArticle Views2019Altmetric-Citations138LEARN 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:Alcohols,Monomers,Organic polymers,Polymers,Ring-opening polymerization Get e-Alerts

A library of polyurethanes and polyureas with different hydrophobicities containing the same acid-degradable dimethyl ketal moiety embedded in the polymer main chain have been prepared. All polymers were synthesized using an AA-BB type step-growth polymerization by reaction of bis(p-nitrophenyl carbamate/carbonate) or diisocyanate monomers with an acid-degradable, ketal-containing diamine. These polymers were designed to hydrolyze at different rates in mildly acidic conditions as a function of their hydrophobicity to afford small molecules only with no polymeric byproduct. The library of polymers was screened for the formation of microparticles using a double emulsion technique. The microparticles that were obtained degraded significantly faster at acidic pH (5.0) than at physiological pH (7.4) with degradation kinetics related to the hydrophobicity of the starting polymer. In vitro studies demonstrated the ability of the FITC-BSA loaded microparticles to be phagocytosed by macrophages resulting in a 10-fold increase in the protein uptake compared to a free protein control; in addition, the microparticles were found to be nontoxic at the concentrations tested of up to 1 mg/mL. The ease of preparation of the polymers coupled with the ability to tune their hydrophobicity and the high acid sensitivity of the microparticles identify this new class of materials as promising candidates for the delivery of bioactive materials.

Abstract Monolithic capillary columns for hydrophobic interaction chromatography (HIC) have been prepared by thermally initiated, single‐step in situ polymerization of mixtures of monovinyl monomers including butyl methacrylate and/or 2‐hydroxyethyl methacrylate, with a divinyl crosslinker glycerol dimethacrylate or 1,4‐butanediol dimethacrylate using two different porogen systems. Two porogenic solvent mixtures were used; one “hydrophilic”, consisting of water, butanediol, and propanol, and one “hydrophobic,” comprising dodecanol and cyclohexanol. The porous structures of the monoliths were characterized and their performance was demonstrated with a separation of a mixture of myoglobin, ribonuclease A, and lysozyme under conditions typical of HIC.

We have designed and synthesized a series of novel nortricyclene and other cycloaliphatic homo-and co-polymers incorporating at high carbon to hydrogen ratio and various structural units for use in 193nm microlithography. The various macromolecules are prepared using a radical cyclopolymerization process involving norbornadienes or other suitable bis-olefinic moieties modified with an imageable functionality. The physical properties of the cyclopolymers may be tuned through copolymerization and simple modifications in the structure and composition of the monomers. The resulting materials may be formulated with a suitable photoacid generator to afford chemically amplified resists. The resists exhibit outstanding dry-etch resistance, good adhesion to silicon, good transparency at 193nm and are uncontaminated by metal catalysts. Development with standard aqueous base affords positive-tone images with resolution of 0.16μm and better. The concept of using self-assembled monolayers of dendrimers for molecular scale imaging using scanning probe lithography is also outlined.

[reaction: see text] Solid functionalized porous monolithic disks with reactive polymer chains grafted to their inner pore surface have been developed for scavenging excess reagents from reaction mixtures. A poly(chloromethylstyrene-co-divinylbenzene) monolith was cut into disks and activated by graft polymerizing 4-vinyl-2,2-dimethylazlactone to its pore surface. In contrast to the direct copolymerization of reactive monomers, grafting increases the accessibility of the reactive groups. Application of the reactive disks is demonstrated in the scavenging of excess amines from reaction mixtures in different solvents.

Abstract Stationary phases for capillary electrochromatography with a longitudinal gradient of functionalities have been prepared via photoinitiated grafting of polymer chains onto the pore surface of a porous polymer monolith. In order to achieve the desired retention and electroosmotic flow, the hydrophobic poly(butyl methacrylate‐ co ‐ethylene dimethacrylate) monolith with optimized porous properties was grafted with a layer of ionizable polymer, poly(2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid). A moving shutter and a neutral density filter were used to control the dose of UV light received at different locations along the monolith in order to create the longitudinal gradient of functionalities. Formation of the desired gradients was confirmed using electron probe microanalysis of different locations along the column. The preparation technique significantly affects performance in the CEC mode as demonstrated on the separations of a model mixture using columns both with homogeneous distribution of grafts and with a gradient of functionality. Columns grafted with the gradient of functionalities were found superior to those functionalized uniformly. A comparison of the performance of the gradient column with another containing evenly distributed functionalities showed the performance benefits of the “gradient” column.

Self-assembled polyester dendritic bow-ties with various peripheral groups were prepared, and\ntheir association constants were measured by <sup>1</sup>H NMR in CDCl<sub>3</sub>. The two complementary dendrons\nwere prepared by attachment of either a bis(adamantylurea) or a glycinylurea to the focal point of\nthe dendron. The parent self-assembled system with benzylidene acetals on one periphery and\nisopropylidene acetals on the other had an association constant of 520 M<sup>-1</sup>. Upon deprotection of\none dendron, the association constant is increased by more than an order of magnitude as the\nsolubility of the hydroxyl-terminated dendron in CDCl<sub>3</sub> is decreased. In contrast, attachment of\ntri(ethylene oxide) units to the periphery of one dendron lowers the association constant by almost\nan order of magnitude. The causes of these relatively large changes in complex strength are\ndiscussed in terms of solubility, steric effects, competitive hydrogen bonding, and the structure of\nthe dendritic scaffold.