A molding process has been used for the preparation of separation media in different shapes such as rods and flat membrane-like disks. The polymerization is carried out using a mixture of monomers, porogenic solvent and free-radical initiator under conditions that afford macroporous materials with through-pores or channels large enough to provide the high flow characteristics required for applications in chromatography. In contrast to classical suspension polymerization, the solubility of monomers in water does not restrict their use. The versatility of the preparation technique is demonstrated in polymerizations involving both hydrophobic and hydrophilic monomers such as styrene, chloromethylstyrene, glycidyl methacrylate, alkyl methacrylates and acrylamide. Techniques have been developed that allow fine control of the porous properties of the polymers. These, in turn, determine the hydrodynamic properties of the separation devices that contain the molded media. Since all the mobile phase must flow through the separation medium, the mass transport within the molded media is accelerated considerably by convection. Therefore, the separations can be performed at much higher flow rates than in packed columns. This is particularly important for separations of large molecules such as proteins for which diffusion is a serious problem that significantly slows down the separation processes. The molded separation media have been used for the separation of biological compounds using gentle chromatographic modes such as hydrophobic interaction, ion-exchange and affinity chromatography during which the biological activity of the separated compounds is completely retained.

Acylation resins in a new monolithic format have been prepared by the functionalization of polyethylene-encased porous poly(chloromethylstyrene-co-divinylbenzene) disks. These disks have been obtained from a monolithic rod prepared by polymerization in a cylindrical glass mold, then cut into a disk format. A free radical azo initiator 4,4'-azobis(4-cyanovaleric acid) attached to available chloromethyl functionalities at the surface of the pores was used to initiate graft polymerization of 4-acetoxystyrene or chloromethylstyrene from the surface. Addition of a small percentage of divinylbenzene to the polymerization mixture leads to the formation of a layer of swellable reactive polymer gel at the surface of the macropores. This both prevents the undesirable increase in flow resistance through the monolith and improves the yield of grafting. The final reaction steps involve formation of an active phenolic moiety grafted to the disks and its reaction with acid anhydride. The use of grafted disks as acylating resin to transform various amines to amides in flow-through operations is demonstrated in a variety of solvents including alcohols. The acylation ability of the depleted disks can easily be recovered, and the disks can be reused many times.

Polar, Monodisperse, Reactive Beads from Functionalized Methacrylate Monomers by Staged Templated Suspension Polymerization

Porous monodisperse poly(methacrylic acid-co-ethylene dimethacrylate) and poly(2-hydroxyethyl methacrylate-co-ethylene dimethacrylate) beads, which can be used as a platform for the production of separation media, polymeric reagents, and supports, have been prepared using the staged templated suspension polymerization process. Since the direct polymerization of methacrylic acid, which would lead to beads bearing carboxyl groups in a single step, is not compatible with the preparation technique, poly(tert-butyl methacrylate-co-ethylene dimethacrylate) beads were prepared and then selectively deprotected. In contrast, beads containing aliphatic hydroxyl groups can be prepared directly despite the high solubility of 2-hydroxyethyl methacrylate in water. The degree of functionalization and porous properties of the beads are largely controlled by the monomer composition in the polymerization mixture. One application for the functionalized beads is the preparation of very selective chiral separation media for HPLC of enantiomers.

Study of the compatibility of blends of polymers and copolymers containing styrene, 4-hydroxystyrene and 4-vinylpyridine

The suspension copolymerization of several t-butoxycarbonyl (t-BOC) protected 4-vinyl phenols with divinylbenzene has been studied to produce high porosity 10 μm bead materials with surface areas of 200–300 m2/g for use as separation media. The choice and amount of porogen is critical for the control of porosity and surface area while particle size and size distribution is controlled by other reaction variables. The t-BOC protecting groups of the polymers are easily removed by thermolysis and the deprotected beads are useful in the separation of amines. The relationship between polymer structure and separation ability in h.p.l.c. has been explored and the effect of alkyl substituents located ortho to the phenolic groups is discussed.

New solid-phase catalysts for asymmetric synthesis: cross-linked polymers containing a chiral Schiff base-zinc complex

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNew solid-phase catalysts for asymmetric synthesis: cross-linked polymers containing a chiral Schiff base-zinc complexShinichi Itsuno, Yoshiki Sakurai, Koichi Ito, Toshihiro Maruyama, Seiichi Nakahama, and J. M. J. FrechetCite this: J. Org. Chem. 1990, 55, 1, 304–310Publication Date (Print):January 1, 1990Publication History Published online1 May 2002Published inissue 1 January 1990https://pubs.acs.org/doi/10.1021/jo00288a051https://doi.org/10.1021/jo00288a051research-articleACS PublicationsRequest reuse permissionsArticle Views1113Altmetric-Citations152LEARN 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

Attachment of drugs to high molecular weight polymers can significantly improve both tumor targeting and therapeutic efficacy due to the enhanced permeability and retention effect observed in tumor tissue. However, the commercial availability of well-defined water-soluble polymeric systems with narrow polydispersities that are biocompatible, nontoxic, and nonimmunogenic is rather limited. To address this need, we have investigated dendritic polymers as promising scaffolds for the preparation of new soluble polymeric drug carriers due to their well-defined molecular architecture and their multiplicity of surface sites. Herein we show the design and synthesis of dendritic polyester systems based on the monomer unit 2,2-bis(hydroxymethyl)propanoic acid as a possible versatile drug carrier. The potent anticancer drug doxorubicin was attached via a pH-sensitive linkage to one of the carriers presented, demonstrating the feasibility of using these polyester dendritic structures to prepare a viable polymer-drug conjugate.

Structures and Properties of Supramolecular Liquid-Crystalline Side-Chain Polymers Built through Intermolecular Hydrogen Bonds

The design, structure, and properties of supramolecular liquid-crystalline side-chain polymers are described. In particular, we show how several simple H-bonding building blocks can be used for the formation of various liquid-crystalline structures. Poly[4-(6-(acryloyloxy)hexyl- and -undecyloxy)benzoic acid] (PmOBA; m = 6, 11) have been employed as polymer components. A variety of supramolecular mesogenic "copolymers" based on one polymeric component have been designed and prepared by simple self-assembly. Cooperation of the hydrogen bond and electron donor−acceptor interactions results in the mesophase stabilization for the "copolymeric" supramolecular structures of PmOBA with a mixture of trans-4-methoxy-4'-stilbazole (1OSz) and trans-4-cyano-4'-stilbazole (SzCN) or trans-4-nitro-4'-stilbazole (SzNO2). When a bifunctional molecule, 4,4'-bipyridine (BPy), is used as a component for "copolymeric" structures, supramolecular copolymeric networks based on PmOBA have been formed by self-assembly. The networks exhibit stable mesomorphic behavior and reversible phase transitions due to the dynamics of the hydrogen bonds.

Immobilization of trypsin onto “molded” macroporous poly(glycidyl methacrylate‐co‐ethylene dimethacrylate) rods and use of the conjugates as bioreactors and for affinity chromatography

Trypsin immobilization onto continuous "molded" rods of porous poly(glycidyl methacrylate-co-ethylene dimethacrylate) and some applications of the conjugate have been studied. The rods polymerized within a tubular mold (chromatographic column), were treated in situ with ethylenediamine, activated with glutaraldehyde and finally modified with trypsin. The performance of the trypsin-modified rods was evaluated and compared to that of poly(glycidyl methacrylate-co-ethylene dimethacrylate) beads, modified with the same enzyme. Overall the enzyme-modified rods performed substantially better than the corresponding beads. In particular, the performance of the molded supports as enzymatic reactors or as chromatographic media benefits greatly from the enhanced mass transfer that is characteristic of the molded rod at high flow rates. © 1996 John Wiley & Sons, Inc.