Synthesis of Poly(2-methyl-2-oxazoline) Star Polymers with a β-Cyclodextrin Core

2012 ◽  
Vol 65 (8) ◽  
pp. 1145 ◽  
Author(s):  
Guillaume Pereira ◽  
Cécile Huin ◽  
Simona Morariu ◽  
Véronique Bennevault-Celton ◽  
Philippe Guégan
Keyword(s):  
Molecular Weight ◽  
Ring Opening ◽  
Allyl Bromide ◽  
Star Polymers ◽  
Star Polymer ◽  
Kinetic Measurements ◽  
Hydrodynamic Volume ◽  
The Core ◽  
Initiation And Propagation ◽  
Propagation Kinetic

Synthesis of star polymers with a β-cyclodextrin (CD) core was undertaken using the arm-first, then the core-first strategy. Cationic ring opening polymerisation (CROP) of 2-methyl-2-oxazoline (MeOx) was first initiated by allyl bromide, and then quenched with heptakis(6-deoxy-6-amino)β-CD in order to get a 7-arm star polymer. Then heptakis(6-deoxy-6-iodo-2,3-di-O-acetyl)β-CD was synthesised in order to get an initiator for the CROP of MeOx. Initiation and propagation kinetic measurements were undertaken and the ratio kp/ki was found to be too high to provide a controlled polymerisation. Using iodine as co-initiator allowed a decrease of the kp/ki ratio that gave better control of the polymerisation. DOSY NMR and viscosity characterisations were undertaken, and both techniques lead to the demonstration of a lower hydrodynamic volume of the star polymers versus the linear counterparts, for compounds of the same molecular weight.

scholarly journals Flexible and rigid core molecules in the synthesis of poly(lactic acid) star polymers

2011 ◽  
Vol 89 (4) ◽  
pp. 499-505 ◽  
Author(s):  
Mitchell R. Perry ◽  
Michael P. Shaver
Keyword(s):  
Molecular Weight ◽  
Star Polymers ◽  
Gel Permeation Chromatography ◽  
Star Polymer ◽  
Poly Lactic Acid ◽  
Melt Crystallization ◽  
Scanning Calorimetry ◽  
The Core ◽  
Total Molecular Weight ◽  
The Individual

This study presents the synthesis and physical characterization of a series of structurally well-defined star-shaped poly(lactic acids). Polymer stars are prepared from a series of multifunctional alcohol cores including flexible polyols pentaerythritol and dipentaerythritol (four-armed and six-armed cores, respectively) and rigid substituted arenes tri(hydroxymethyl)benzene and hexa(hydroxymethyl)benzene. Utilizing a tin(II) octanoate catalyst, arms of 10 monomer units long are built from rac-lactide and l-lactide to form atactic and isotactic star polymers. Polymers were subsequently characterized by means of NMR spectroscopy, gel permeation chromatography, differential scanning calorimetry, and thermogravimetric analysis. Our results support previous work that suggests that the length of the individual arms, not the total molecular weight, correlates to physical characteristics including glass, melt, crystallization, and decomposition temperatures. In addition, differences between core molecules suggest that the chemical nature of the core can significantly alter the physical properties of the star polymer. Trends in crystallization and glass transition temperatures relative to the core used merit further study and correlate closest to the molecular weight and the number of arms emanating from the star core. It is also clear that the rigidity provided by aromatic cores has a significant effect on the melting temperatures of these macromolecules.

Synthesis and Micellar Properties of Star-Shaped Poly(ε-Caprolactone)-Dextran Amphiphilic Block Copolymer

2011 ◽  
Vol 239-242 ◽  
pp. 2711-2716
Author(s):  
Xue Qing Liu ◽  
Ji Yan Liu
Keyword(s):  
Ring Opening ◽  
Ph Value ◽  
Star Polymer ◽  
Element Analysis ◽  
H Nmr ◽  
Micellar Properties ◽  
The Core ◽  
Micelle Size ◽  
Form Star ◽  
End Group

6-arm star-shaped Poly (ε-caprolactone)-dextran (sPCL-dextran) was synthesized and characterized. The core of the star polymer is dipentaerythritol, the inner block in the arm is hydrophobic poly (ε-caprolactone) (PCL), and the outer block in the arm is hydrophilic dextran. The synthesis involves three steps: (1) The ring-opening polymerization of ε-caprolactone (CL) initiated by dipentaerythritol produces 6-arm star-shaped PCL (sPCL-OH). (2) The sPCL-OH reacts with acryloyl chloride to get star-shaped PCL with acrylate end group (sPCL-CH=CH2). (3) The amino ended dextran (dextran-NH2) is then attached to sPCL-CH=CH2 terminus by Micheal addition to form star-shaped sPCL-dextran. The architecture of products was characterized with 1H NMR, GPC and element analysis. Micellization of sPCL-dextran in aqueous solutions was investigated by DLS. The results showed that the micelle size (Rh) and size distribution are related to the concentration of the sPCL-dextran. Salt, pH value and temperature have no obvious influence on the Rh.

An aggregation-induced emission star polymer with pH and metal ion responsive fluorescence

2016 ◽  
Vol 7 (42) ◽  
pp. 6513-6520 ◽  
Author(s):  
Yuming Zhao ◽  
Wen Zhu ◽  
Ying Wu ◽  
Lin Qu ◽  
Zhengping Liu ◽  
...  
Keyword(s):  
Metal Ions ◽  
Ring Opening ◽  
Metal Ion ◽  
Star Polymers ◽  
Star Polymer ◽  
One Pot ◽  
Active Star ◽  
Metathesis Polymerization ◽  
Aggregation Induced Emission ◽  
Emission Star

A one-pot strategy from ring-opening metathesis polymerization was employed to prepare AIE-active star polymers, which were designed to have multi-responsive fluorescence to varied stimuli including pH, CO2, and metal ions.

scholarly journals Star Polymer-Drug Conjugates with pH-Controlled Drug Release and Carrier Degradation

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
H. Kostková ◽  
L. Schindler ◽  
L. Kotrchová ◽  
M. Kovář ◽  
M. Šírová ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Star Polymers ◽  
Controlled Drug Release ◽  
Blood Stream ◽  
In Vitro Cytotoxicity ◽  
Star Polymer ◽  
Molar Ratio ◽  
Design Synthesis ◽  
Dendritic Core

In this study, we describe the design, synthesis, and physicochemical and preliminary biological characteristics of new biodegradable, high-molecular-weight (HMW) drug delivery systems with star-like architectures bearing the cytotoxic drug doxorubicin (DOX) attached by a hydrazone bond-containing spacer. The star polymers were synthesized by grafting semitelechelic N-(2-hydroxypropyl) methacrylamide (HPMA) copolymers on a 2,2-bis(hydroxymethyl)propionic acid- (bis-MPA-) based polyester dendritic core. The molecular weight of the star polymers ranged from 280 to 450 000 g/mol and could be adjusted by proper selection of the bis-MPA dendrimer generation and by considering the polymer to dendrimer molar ratio. The biodegradation of the polymer conjugates is based on the spontaneous slow hydrolysis of the dendritic core in neutral physiological conditions. Hydrazone spacers in the conjugates were fairly stable at neutral pH (7.4) mimicking blood stream conditions, and DOX was released from the conjugates under mild acidic conditions simulating the tumor cell microenvironment in endosomes and lysosomes (pH 5). Finally, we have shown the significant in vitro cytotoxicity of the star polymer-DOX conjugate on selected cancer cell lines with IC50 values almost comparable with that of the free drug and higher than that observed for a linear polymer-DOX conjugate with much lower molecular weight.

Design and Synthesis of a Miktoarm Star PMMAZO-(PCL)2 Copolymer

2011 ◽  
Vol 332-334 ◽  
pp. 2089-2092
Author(s):  
Jian Fang Chen ◽  
Ai Hua Ling
Keyword(s):  
Chemical Modification ◽  
Ring Opening ◽  
Liquid Crystalline ◽  
Star Polymers ◽  
Star Polymer ◽  
Side Chain ◽  
Nuclear Resonance ◽  
Design And Synthesis ◽  
Gel Permeation ◽  
Miktoarm Star

A series of novel miktoarm star polymers were synthesized by combination of at-om transfer radical polymerization(ATRP), chemical modification and ring-opening polymeri-zation(ROP). These miktoarm star polymers carring one poly[6-(4-methoxy-4’-oxy-azobenzene) hexylmethacrylate] azobenzene (PMMAZO) side-chain liquid crystalline(LC) arm and two polycaprolactone(PCL) arms. These precursors and miktoarm star polymers were characterized by proton nuclear resonance (1H-NMR), and gel permeation chramatograph(GPC). The information of PMMAZO(OH)2 and PMMAZO-(PCL)2 miktoarm star polymer confirmed the expected structure.

Peptide-Based Star Polymers as Potential siRNA Carriers

2014 ◽  
Vol 67 (4) ◽  
pp. 592 ◽  
Author(s):  
Shu Jie Lam ◽  
Adrian Sulistio ◽  
Katharina Ladewig ◽  
Edgar H. H. Wong ◽  
Anton Blencowe ◽  
...  
Keyword(s):  
Ring Opening ◽  
Star Polymers ◽  
Pamam Dendrimers ◽  
Water Soluble ◽  
Poly Ethylene Glycol ◽  
The Core ◽  
Poly Ethylene ◽  
Interfering Rna ◽  
Carbodiimide Coupling

16- and 32-arm star polymers were synthesised using poly(amido amine) (PAMAM) dendrimers as multifunctional initiators for the ring-opening polymerisation (ROP) of ϵ-Z-l-lysine N-carboxyanhydride (Lys NCA) via the core-first approach. The resulting star polymers were subsequently post-functionalised with poly(ethylene glycol) (PEG) via carbodiimide coupling, potentially improving the biodistribution of the stars in vivo. De-protection of the carboxybenzyl (Cbz)-protected star arms yielded water-soluble cationic poly(l-lysine) (PLL) star polymers with hydrodynamic radii ranging from 2.0 to 3.3 nm. Successful complexation of the PLL star polymers with double-stranded oligodeoxynucleotides (ODNs)—a mimic for small interfering RNA (siRNA)—was achieved at a nitrogen-to-phosphate (N/P) ratio of 5. Cell viability studies using HEK293T cells indicated the ‘safe’ concentration for these polymers is within a suitable window for the delivery of siRNA therapeutics.

Molecular weight (hydrodynamic volume) dictates the systemic pharmacokinetics and tumour disposition of PolyPEG star polymers

2015 ◽  
Vol 11 (8) ◽  
pp. 2099-2108 ◽  
Author(s):  
Song Yang Khor ◽  
Jinming Hu ◽  
Victoria M. McLeod ◽  
John F. Quinn ◽  
Mark Williamson ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Star Polymers ◽  
Hydrodynamic Volume

scholarly journals Ring opening metathesis polymerization of cyclopentene using a ruthenium catalyst confined by a branched polymer architecture

2016 ◽  
Vol 7 (17) ◽  
pp. 2923-2928 ◽  
Author(s):  
Clément Mugemana ◽  
Konstantin V. Bukhryakov ◽  
Olivier Bertrand ◽  
Khanh B. Vu ◽  
Jean-François Gohy ◽  
...  
Keyword(s):  
Ring Opening ◽  
Ruthenium Catalyst ◽  
Star Polymer ◽  
Ring Opening Metathesis Polymerization ◽  
Polymer Architecture ◽  
Branched Polymer ◽  
Metathesis Polymerization ◽  
The Core ◽  
Metathesis Catalyst

A Grubbs-type Ru alkene metathesis catalyst has been covalently anchored in the core of a globular star polymer. The spatially-confined catalyst is capable of efficient ring-opening metathesis polymerization of cyclopentene, a low-strain monomer.

scholarly journals Synthesis of Soluble Star-Shaped Polymers via In and Out Approach by Ring-Opening Metathesis Polymerization (ROMP) of Norbornene: Factors Affecting the Synthesis

Catalysts ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 670 ◽  
Author(s):  
Zelin Sun ◽  
Kazuya Morishita ◽  
Kotohiro Nomura
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Ring Opening ◽  
Core Formation ◽  
Ring Opening Metathesis Polymerization ◽  
Metathesis Polymerization ◽  
The Core ◽  
Molecular Weight Distributions ◽  
Weight Distributions ◽  
Formation Step

The methods for one-pot synthesis of ‘soluble’ star-shaped polymers by sequential living ring-opening metathesis polymerization (ROMP) of norbornene (NBE) and cross-linking (CL) reagent using Mo(CHCMe2Ph)(N-2,6-iPr2C6H3)(OtBu)2 have been explored. The method (called the “in and out” or core-first approach) basically consists of (i) the living ROMP of NBE (formation of arm), (ii) reaction with CL (formation of core), (iii) additional living ROMP of NBE (propagating arms from the core, formation of star), (iv) end-modification via Wittig-type cleavage of metal–carbon double bonds containing polymer chain with aldehyde. Two different approaches in the core formation step (reaction with CL mixed with/without NBE) for synthesis of the high molecular weight star-shaped ROMP polymers with more branching, unimodal molecular weight distributions have been explored in detail. The method (reacting CL with NBE in the core formation step) under highly diluted conditions afforded the high molecular weight polymers with unimodal molecular weight distributions.

Separation of linear and star-shaped polystyrenes by two-dimensional chromatography

e-Polymers ◽  
2005 ◽  
Vol 5 (1) ◽  
Author(s):  
Johannes Gerber ◽  
Wolfgang Radke
Keyword(s):  
Molecular Weight ◽  
Size Exclusion Chromatography ◽  
Star Polymers ◽  
Size Exclusion ◽  
Two Dimensional ◽  
Clear Separation ◽  
Hydrodynamic Volume ◽  
Exclusion Chromatography ◽  
Total Molecular Weight ◽  
Gradient Chromatography

AbstractInvestigation of star-shaped polystyrenes using gradient chromatography shows a retention that only depends on the total molecular weight and not on the number or molecular weight of the arms. In contrast, size-exclusion chromatography (SEC) separates according to hydrodynamic volume. For a mixture of a star polymers having an arm molecular weight of 4800 and a linear polystyrene a direct 2-dimensional separation using gradient chromatography as a first dimension and SEC as a second dimension resulted in a clear separation of the different topologies. Star polymers of higher arm molecular weight could not be separated from their linear analogues by direct coupling of gradient chromatography and SEC.

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