Unprotected Monomers Research Articles

RAFT dispersion polymerization induced self-assembly (PISA) of boronic acid-substituted acrylamides

For the unprotected monomer, the boroxine core of nanoparticles allows transitions to higher order morphologies, while worms and vesicles are yielded directly from PISA of the pinacol ester-protected monomer.

An Upgraded "Two-in-One" Strategy toward Highly Crystalline Covalent Organic Frameworks.

A highly crystalline bicarbazole-based covalent organic framework (BCzP-COF) was synthesized via an upgraded "two-in-one" strategy by the self-polycondensation of A2 B2 monomer with two neopentyl acetal and two amine groups. Such a strategy is propitious to afford higher crystallinity, larger special surface areas and better morphology than that of using unprotected monomer with free aldehydes and amines. Additionally, the off-white powder of BCzP-COF could serve as acidichromism sensor with a significant color change. Intriguingly, the conductivity of the protonated BCzP-COF can improve by six orders of magnitude compared to that of the pristine samples. This work has the potential to lead to bicarbazole-functional materials for chemosensors and electronic devices.

Synthesis of Chain-End Functionalized Glycopolymers via Cyanoxyl-Mediated Free Radical Polymerization (CMFRP).

Glycopolymers are often used as glyco-macroligands for biological research and biomedical applications in carbohydrate recognitions. Chain-end functionalized glycopolymers show more potential for practical applications, such as protein modification and solid-phase bioassays. In particular, the chain-end group allows for direct one-to-one attachment or facilitates site-specific and oriented immobilization onto solid surfaces. A series of derivatized arylamine initiators are used to generate chain-end functionalized glycopolymers by cyanoxyl-mediated free radical polymerization (CMFRP). Important features of this strategy include the capacity to produce polymers of low polydispersity (PDI <1.5) under aqueous conditions using unprotected monomers bearing a wide range of functional groups. In addition, it provides a one-pot method to synthesize α,ω-telechelic glycopolymers with derivatized arylamine at one site and O-cyanate at the other site. In the process, the capacity to orthogonally label glycopolymers or otherwise conjugate them to proteins and other molecules is greatly enhanced.

Double‐Hydrophilic and Amphiphilic Block Copolymers Synthesized by RAFT Polymerization of Monomers Carrying Chiral Amino Acids

AbstractDouble‐hydrophilic and amphiphilic block copolymers with characteristic chiroptical properties (L‐L and L‐D types) were synthesized by RAFT polymerization. Five N‐acryloylamino acids with different hydrophilicity and chirality were employed, which included A‐(L)Phe‐OMe, A‐(L)Phe‐OH, A‐(L)Ala‐OH, and their D‐forms [A‐(D)Phe‐OH and A‐(D)Ala‐OH], respectively. The RAFT polymerization of the unprotected monomer using the hydrophobic and hydrophilic macro‐chain transfer agents provided well‐defined block copolymers. Chiroptical properties and assembled structures were evaluated by CD, UV‐vis and DLS measurements.magnified image

Recent advances in the synthesis of well‐defined glycopolymers

AbstractGlycopolymers are receiving increasing interest due to their application in areas, such as glycomics, medicine, biotechnology, sensors, and separation science. Consequently, new methods for their synthesis are constantly being developed, with an increasing emphasis on the preparation of well‐defined polymers and on the production of complex macromolecular architectures such as stars. This review covers recent developments in the synthesis of glycopolymers, with a particular emphasis on (i) the use of controlled radical polymerization to prepare well‐defined glycopolymers from unprotected monomers and (ii) postpolymerization modification strategies using reactive polymer precursors (including “click” reactions). Recent work on the production of glycosylated polypeptides, which are under investigation as mimics of naturally occurring glycoproteins, is also included. The authors offer some suggestions as to future developments and remaining challenges in this topical area of polymer chemistry. © 2007 Wiley Periodicals, Inc. J Polym Sci PartA: Polym Chem45: 2059–2072, 2007

Biotinylated Glycopolymers Synthesized by Atom Transfer Radical Polymerization

Biotinylated glycopolymers that bind to the protein streptavidin were synthesized by atom transfer radical polymerization (ATRP). Poly(methacrylate)s with pendent N-acetyl-d-glucosamines were prepared by polymerizing the protected monomer, followed by deprotection. Alternatively, the unprotected monomer was directly polymerized. Both paths provided well-defined glycopolymers with narrow molecular weight distributions (PDI = 1.07-1.23). The number-average molecular weights determined by gel permeation chromatography increased with increasing initial monomer-to-initiator ratios. The polymers were synthesized using a biotin-functionalized initiator for ATRP. Confirmation of the end group and binding to the protein streptavidin was achieved by (1)H NMR and surface plamon resonance.

Well-Defined Glycopolymers from RAFT Polymerization: Poly(methyl 6-O-methacryloyl-α-d-glucoside) and Its Block Copolymer with 2-Hydroxyethyl Methacrylate

The glycomonomer methyl 6-O-methacryloyl-α-d-glucoside was prepared by lipase-catalyzed transesterification of vinyl methacrylate with methyl α-d-glucoside in dry acetonitrile. The desired 6-O regioisomer was obtained in good yield and its structure confirmed by 1H−1H and 1H−13C correlation NMR spectroscopy. Reversible addition−fragmentation chain transfer (RAFT) polymerization of the unprotected monomer was performed directly in aqueous solution using (4-cyanopentanoic acid)-4-dithiobenzoate as the chain transfer agent to give poly(methyl 6-O-methacryloyl-α-d-glucoside) with Mn between 16 and 103 kDa (1H NMR) and polydispersities as low as 1.10. Chain extension of one of these polymers with 2-hydroxyethyl methacrylate afforded the novel hydrophilic−hydrophilic block copolymer poly[(methyl 6-O-methacryloyl-α-d-glucoside)-block-(2-hydroxyethyl methacrylate)].

Facile synthesis of chain-end functionalized glycopolymers for site-specific bioconjugation.

A series of derivatized arylamine initiators were used to generate chain-end functionalized glycopolymers by cyanoxyl-mediated free-radical polymerization. Significant features of this strategy include the capacity to produce polymers of low polydispersity (PDI < 1.5) under aqueous conditions using unprotected monomers bearing a wide range of functional groups. In addition, the presence of a phenyl ring simplifies calculation of polymer saccharide content and molar mass by (1)H NMR. It is particularly noteworthy, however, that derivatized arylamine initiators in conjunction with the presence of a terminal cyanate group provide a convenient approach for synthesizing polymers with a variety of distinct functional groups at alpha and omega chain ends. In the process, the capacity to label glycopolymers or otherwise conjugate them to proteins or other molecules is greatly enhanced.

Chemoenzymatic synthesis of narrow-polydispersity glycopolymers: poly(6-O-vinyladipoyl-D-glucopyranose).

The glycomonomer 6-O-vinyladipoyl-D-glucopyranose was prepared via lipase catalyzed transesterification of divinyladipate with alpha-D-glucopyranose in dry acetonitrile and acetone. The desired 6-O regioisomer was obtained in good yield, and its structure was confirmed by correlation NMR spectroscopy. Controlled radical polymerization of the unprotected monomer was performed in protic media using both xanthate and dithiocarbamate as chain transfer agents to give poly(6-O-vinyladipoyl-D-glucopyranose) with Mn of 17 and 19 kDa (SEC) respectively and a polydispersity as low as 1.10. To the best of our knowledge, this is the first example of a narrow-polydispersity, poly(vinyl ester)-like glycopolymer.

The Dissolution Behavior of Tetrafluoroethylene-based Fluoropolymers for 157-nm Resist Materials

Main-chain-fluorinated base-resins, using the copolymer of tetrafluoroethylene and functional (hexafluoroisopropanol (HFA) group) norbornene, were synthesized. Partial protection of the hydroxyl group as an ethoxymethyl group was achieved by two methods: by copolymerization (Method A) or by polymer reaction (Method B). The partial protection by copolymerization was conducted by copolymerizing TFE with a mixture of protected and unprotected monomers (Method A, copolymerization). Partial protection was also carried out by reacting the hydroxyl group of the polymer, which is composed of TFE and unprotected monomers with ethoxymethyl chloride in the presence of an amine (Method B). In the polymer reaction, only the exo position of the norbornene unit was protected. Their fundamental properties, such as transparency at 157 nm and solubility in a standard alkaline developer, were characterized and studied. High transparency, i.e., absorbance better than 0.4 μm-1, was achieved with both methods. However, the polymer prepared by the polymer reaction (Method B) was deprotected more quickly; it also had a higher dissolution rate and stronger development contrast than the polymer prepared by copolymerization (Method A). Positive-working resists based on these fluororesins were developed and 55 nm dense lines could be delineated by exposure at 157 nm wavelength with alternating phase shift mask on a 0.9 NA 157 nm exposure tool.

Reactive groups on polymer coated electrodes, 12. New conducting carrier materials: polyalkylthiophene functionalized with amino group and its protected forms

The synthesis and electropolymerization of 3-alkylthiophenes functionalized with a terminal amino group and its protected forms are reported. As expected, due to the strong electronic interference of the amino group, the electropolymerization of the unprotected monomer is fully inhibited. After protection of the amino group the polymerizability of the corresponding monomers is considerably improved; however, the successful polymerization process clearly depends on the nature of the used protective group. Only such monomers in which the nucleophilic character of the amino group is strongly suppressed by a suitable protective group undergo electropolymerization to form the corresponding electroactive polymers. The obtained polymers are electrochemically stable and, besides the typical properties such as redox behavior and electrochromism, they exhibit a distinct solvatochromic behavior. Electrical conductivity measurements on their oxidized forms by means of the two-probe method give values in the range of 10–3 to 10–2 S·cm–1. The feasibility of using the resulting polymers as conducting carrier materials was demonstrated by the removal of the protecting groups and the subsequent attachment of a redox active ferrocene compound. Electrochemical and spectroscopic experiments confirmed that after the polymer analogous reaction the used redox active ferrocene model compound is covalently immobilized onto the polymer surface and the electroactivity of the bonded redox groups as well as the carrier materials is retained.

Synthesis of tailor-made copolymers containing free or protected catechol residues for selective flocculation of mineral dispersions

pH-Controlled selective polymeric flocculants for titanium mineral dispersions have been designed and prepared through the synthesis of five new vinyl monomers containing catechol residues in free or protected form and through their radical copolymerization with acrylic or methacrylic acid. The synthesis of copolymers with unprotected catechol groups has been studied either by directly copolymerizing unprotected monomers in the presence of tri-n-butylborane or by chemically transforming copolymers obtained from protected monomers.