Syntheses of Tadpole- and Eight-Shaped Polystyrenes Using Cyclic Polystyrene as a Building Block

Kubo, Masataka; Hayashi, Takeshi; Kobayashi, Hidenori; Itoh, Takahito

doi:10.1021/ma971068a

Cited by 68 publications

(76 citation statements)

References 19 publications

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“…43 The second one employs the intermolecular ring-closure reaction between an R,R-homobifunctional polymer precursor and a complementary bifunctional reactive reagent. 47,48 The third synthetic strategy is based on the coupling reaction between functionalized cyclic and linear polymer precursors. 45,49 Various intra-or intermolecular ring closure/coupling approaches such as electrostatic self-assembly and covalent fixation (ESA-CF), 50,51 amidation/esterification, 47,52,53 etherification reaction (hydroxyl 33 or thiol functionalities 54 ), and high-efficiency and quantitative click reactions 41,42,55 have been utilized.…”

Section: ' Introductionmentioning

confidence: 99%

Synthesis of Amphiphilic Tadpole-Shaped Linear-Cyclic Diblock Copolymers via Ring-Opening Polymerization Directly Initiating from Cyclic Precursors and Their Application as Drug Nanocarriers

2011

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We report on the facile synthesis of well-defined amphiphilic and thermoresponsive tadpole-shaped linear-cyclic diblock copolymers via ring-opening polymerization (ROP) directly initiating from cyclic precursors, their self-assembling behavior in aqueous solution, and the application of micellar assemblies as controlled release drug nanocarriers. Starting from a trifunctional core molecule containing alkynyl, hydroxyl, and bromine moieties, alkynyl-(OH)-Br, macrocyclic poly(N-isopropylacrylamide) (c-PNIPAM) bearing a single hydroxyl functionality was prepared by atom transfer radical polymerization (ATRP), the subsequent end group transformation into azide functionality, and finally the intramacromolecular ring closure reaction via click chemistry. The target amphiphilic tadpoleshaped linear-cyclic diblock copolymer, (c-PNIPAM)-b-PCL, was then synthesized via the ROP of ε-caprolactone (CL) by directly initiating from the cyclic precursor. In aqueous solution at 20°C, (c-PNIPAM)-b-PCL self-assembles into spherical micelles consisting of hydrophobic PCL cores and well-solvated coronas of cyclic PNIPAM segments. For comparison, linear diblock copolymer with comparable molecular weight and composition, (l-PNIPAM)-b-PCL, was also synthesized. It was found that the thermoresponsive coronas of micelles self-assembled from (c-PNIPAM)-b-PCL exhibit thermoinduced collapse and aggregation at a lower critical thermal phase transition temperature (T c ) compared with those of (l-PNIPAM)-b-PCL. Temperature-dependent drug release profiles from the two types of micelles of (c-PNIPAM)-b-PCL and (l-PNIPAM)-b-PCL loaded with doxorubicin (Dox) were measured, and the underlying mechanism for the observed difference in releasing properties was proposed. Moreover, MTT assays revealed that micelles of (c-PNIPAM)-b-PCL are almost noncytotoxic up to a concentration of 1.0 g/L, whereas at the same polymer concentration, micelles loaded with Dox lead to ∼60% cell death. Overall, chain topologies of thermoresponsive block copolymers, that is, (c-PNIPAM)-b-PCL versus (l-PNIPAM)-b-PCL, play considerable effects on the self-assembling and thermal phase transition properties and their functions as controlled release drug nanocarriers. ' INTRODUCTIONIn the past decades, enduring attention has been paid to explore the intrinsic correlation between the chain topology of block copolymers and their physical properties, self-assembling behavior in selective solvents or in bulk states, and the associated functional applications. 1-3 It has been well-established that the topological structures and chemical composition of nonlinearshaped block copolymers can exhibit dramatic effects on the solution properties and self-assembling morphologies as compared with their linear counterpart. [4][5][6][7][8][9] It is worthy of noting that the developments of a variety of controlled radical polymerization techniques 10 such as atom transfer radical polymerization (ATRP), 11-13 reversible addition-fragmentation chain transfer (RAFT) polymerization, [14][...

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Section: ' Introductionmentioning

confidence: 99%

Synthesis of Amphiphilic Tadpole-Shaped Linear-Cyclic Diblock Copolymers via Ring-Opening Polymerization Directly Initiating from Cyclic Precursors and Their Application as Drug Nanocarriers

2011

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“…[25][26][27] Recently, the electrostatic self-assembly and covalent fixation process has successfully been applied to the efficient synthesis of a series of multicyclic polymers (Fig. 9).…”

Section: Dicyclic and Tricyclic Polymer Topologiesmentioning

confidence: 99%

“…A prototype of such topological block copolymers is a tadpole polymer, produced from a simple ring and outward branch segments. 27,30,31 The electrostatic self-assembly and covalent fixation process has been applied to prepare such constructions (Fig. 9).…”

Section: Topological Block Copolymersmentioning

confidence: 99%

Topological polymer chemistry by electrostatic self‐assembly

Tezuka¹

2003

J. Polym. Sci. A Polym. Chem.

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Recent developments in topological polymer chemistry are outlined. First, nonlinear polymer topologies are systematically classified on the basis of topological considerations of constitutional isomerism in a series of alkanes (C n H 2nϩ2 ), monocycloalkanes (C n H 2n ), and polycycloalkanes (C n H 2nϪ2 , C n H 2nϪ4 , etc.). Various pairs of topological isomers are identified in randomly coiled, flexible polymer molecules with cyclic and branched structures. An electrostatic self-assembly and covalent fixation strategy has subsequently been developed for the efficient synthesis of a variety of topologically unique polymers, including monocyclic and polycyclic polymers, topological isomers, and topological block copolymers. In this process, new telechelics with moderately strained cyclic onium salt groups carrying multifunctional carboxylate counteranions have been designed as key polymeric precursors. Further extensions of topological polymer chemistry have been achieved by the use of cyclic telechelics (kyklo-telechelics) and cyclic macromonomers, obtainable also by means of the electrostatic self-assembly and covalent fixation process.

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“…[1][2][3][4][5][6][7] To date, cyclic polymers with different structures such as diblock, [8] triblock terpolymer, [9] eight-shaped, [10] and tadpole copolymers [11][12][13][14][15] have been synthesized either by end-to-end linking or ring-expansion process. [16][17][18][19][20] Among them, tadpole homo/copolymers consisting of a ring polymer as a head and one linear polymer as a tail, are very interesting for rheology and self-assembly studies, since they combine two topologies in the same molecule.…”

Section: Introductionmentioning

confidence: 99%

“…[21] The third utilizes intramolecular cyclization coupling between the two end-functionalized arms of a threearm star polymer. High-efficient coupling reactions [11,22] including Diels-Alder [23] and copper-catalyzed azidealkyne cycloaddition (CuAAC) [11,15] have been used for the intracyclization. Lately, the Glaser coupling, involving reaction between alkyne groups, has been widely used in organic [24] and polymer synthesis.…”

mentioning

confidence: 99%

Polyethylene‐Based Tadpole Copolymers

Alkayal

Zhang

Bilalis

et al. 2017

Macro Chemistry & Physics

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Novel well-defined polyethylene-based tadpole copolymers {(c-PE)-b-PS, PE: polyethylene, PS: polystyrene} with ring PE head and linear PS tail are synthesized by combining polyhomologation, atom transfer radical polymerization (ATRP), and Glaser coupling reaction. The OH groups of the 3-miktoarm star copolymers (PE-OH) 2 -b-PS, synthesized by polyhomologation and ATRP, are transformed to alkyne groups by esterification with propiolic acid, followed by Glaser cyclization and removal of the unreacted linear with Merrifield's resin-azide. The characterization results of intermediates and final products by high-temperature size exclusion chromatography, 1 H NMR spectroscopy, and differential scanning calorimetry confirm the tadpole topology.

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Syntheses of Tadpole- and Eight-Shaped Polystyrenes Using Cyclic Polystyrene as a Building Block

Cited by 68 publications

References 19 publications

Synthesis of Amphiphilic Tadpole-Shaped Linear-Cyclic Diblock Copolymers via Ring-Opening Polymerization Directly Initiating from Cyclic Precursors and Their Application as Drug Nanocarriers

Synthesis of Amphiphilic Tadpole-Shaped Linear-Cyclic Diblock Copolymers via Ring-Opening Polymerization Directly Initiating from Cyclic Precursors and Their Application as Drug Nanocarriers

Topological polymer chemistry by electrostatic self‐assembly

Polyethylene‐Based Tadpole Copolymers

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