End group polarity and block symmetry effects on cloud point and hydrodynamic diameter of thermoresponsive block copolymers

2015 ◽  
Vol 53 (24) ◽  
pp. 2838-2848 ◽  
Author(s):  
Xu Xiang ◽  
Xiaochu Ding ◽  
Ning Chen ◽  
Beilu Zhang ◽  
Patricia A. Heiden
Keyword(s):  
Block Copolymers ◽  
Cloud Point ◽  
Hydrodynamic Diameter ◽  
End Group

Tuning the synthesis of fully conjugated block copolymers to minimize architectural heterogeneity

2017 ◽  
Vol 5 (38) ◽  
pp. 20412-20421 ◽  
Author(s):  
Youngmin Lee ◽  
Melissa P. Aplan ◽  
Zach D. Seibers ◽  
S. Michael Kilbey ◽  
Qing Wang ◽  
...  
Keyword(s):  
Block Copolymers ◽  
Group Composition ◽  
Feed Ratio ◽  
End Group

Control of conversion, end group composition, and feed ratio is crucial to minimize homopolymer impurities in the synthesis of conjugated block copolymers for photovoltaics.

Double Thermoresponsive Block Copolymers Featuring a Biotin End Group

2010 ◽  
Vol 11 (9) ◽  
pp. 2432-2439 ◽  
Author(s):  
Florian D. Jochum ◽  
Peter J. Roth ◽  
Daniel Kessler ◽  
Patrick Theato
Keyword(s):  
Block Copolymers ◽  
End Group

RAFT Polymerization of Monomers with Highly Disparate Reactivities: Use of a Single RAFT Agent and the Synthesis of Poly(styrene-block-vinyl acetate)

2013 ◽  
Vol 66 (12) ◽  
pp. 1564 ◽  
Author(s):  
Lily A. Dayter ◽  
Kate A. Murphy ◽  
Devon A. Shipp
Keyword(s):  
Block Copolymers ◽  
Vinyl Acetate ◽  
Chain Transfer ◽  
Raft Polymerization ◽  
Good Control ◽  
Scanning Calorimetry ◽  
Styrene Polymerization ◽  
Reversible Addition ◽  
Raft Agent ◽  
End Group

A single reversible addition–fragmentation chain transfer (RAFT) agent, malonate N,N-diphenyldithiocarbamate (MDP-DTC) is shown to successfully mediate the polymerization of several monomers with greatly differing reactivities in radical/RAFT polymerizations, including both vinyl acetate and styrene. The chain transfer constants (Ctr) for MDP-DTC for both these monomers were evaluated; these were found to be ~2.7 in styrene and ~26 in vinyl acetate, indicating moderate control over styrene polymerization and good control of vinyl acetate polymerization. In particular, the MDP-DTC RAFT agent allowed for the synthesis of block copolymers of these two monomers without the need for protonation/deprotonation switching, as has been previously developed with N-(4-pyridinyl)-N-methyldithiocarbamate RAFT agents, or other end-group transformations. The thermal properties of the block copolymers were studied using differential scanning calorimetry, and those with sufficiently high molecular weight and styrene composition appear to undergo phase separation. Thus, MDP-DTC may be useful for the production of other block copolymers consisting of monomers with highly dissimilar reactivities.

Synthesis of Thermo-Responsive Fluorinated Star-Shaped Polymers by Living Cationic Polymerization

2011 ◽  
Vol 1312 ◽  
Author(s):  
Tomomi Irita ◽  
Katsuhiko Imoto ◽  
Takabumi Nagai ◽  
Sadahito Aoshima
Keyword(s):  
Aqueous Solutions ◽  
Cloud Point ◽  
Cationic Polymerization ◽  
Solution Temperature ◽  
Responsive Polymers ◽  
Molecular Weight Distributions ◽  
Living Cationic Polymerization ◽  
Bifunctional Initiators ◽  
Cloud Points ◽  
End Group

ABSTRACTWell-controlled fluorinated star-shaped polymers with oxyethylene units were designed and synthesized by living cationic polymerization. These fluorinated star-shaped polymers were prepared using successive fluorinated initiators to generate fluorinated, end-functionalized and hydrophilic segments with oxyethylene. Poly(vinyl ether)s with oxyethylene units are known to be thermo-responsive polymers that exhibit a lower critical solution temperature (LCST) in aqueous solutions. These novel fluorine-containing star-shaped polymers with oxyethylene were also thermo-responsive, as expected. In addition, the hetero-fluorinated star-shaped polymers with oxyethylene segments and different fluorine compositions were synthesized with various bifunctional initiators by living cationic polymerization having narrow molecular weight distributions (Mw/Mn=1.23−1.29) and contained very little, if any, presence of the linear homopolymer precursor, as evidenced by GPC. The LCST of this polymer depended on the end group fluorine composition and significant changes in cloud points were observed in water, as confirmed by static light scattering (SLS) measurements. As an example, aqueous solutions the star-shaped polymers without fluorine terminal groups showed no cloud point below up to 60 ºC in aqueous solution. After the fluoro-functionality was incorporated into the terminal groups, the cloud point of the aqueous solutions decreased to almost 20 ºC.

Block copolymers and telechelic oligomers by end group reaction of polymethacrylates

1996 ◽  
Vol 102 (1) ◽  
pp. 91-98 ◽  
Author(s):  
Eberhard Esselbom ◽  
Jürgen Fock ◽  
Arno Knebelkamp
Keyword(s):  
Block Copolymers ◽  
Group Reaction ◽  
End Group

scholarly journals Bio-Inspired Amphiphilic Block-Copolymers Based on Synthetic Glycopolymer and Poly(Amino Acid) as Potential Drug Delivery Systems

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 183 ◽  
Author(s):  
Mariia Levit ◽  
Natalia Zashikhina ◽  
Alena Vdovchenko ◽  
Anatoliy Dobrodumov ◽  
Natalya Zakharova ◽  
...  
Keyword(s):  
Amino Acid ◽  
Block Copolymers ◽  
Raft Polymerization ◽  
Amphiphilic Block Copolymers ◽  
Breast Adenocarcinoma ◽  
Hydrodynamic Diameter ◽  
Amphiphilic Copolymers ◽  
Lung Carcinoma Cells ◽  
Biodegradable Poly ◽  
Human Lung Carcinoma

In this work, a method to prepare hybrid amphiphilic block copolymers consisting of biocompatible synthetic glycopolymer with non-degradable backbone and biodegradable poly(amino acid) (PAA) was developed. The glycopolymer, poly(2-deoxy-2-methacrylamido-D-glucose) (PMAG), was synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. Two methods for modifying the terminal dithiobenzoate-group of PMAG was investigated to obtain the macroinitiator bearing a primary aliphatic amino group, which is required for ring-opening polymerization of N-carboxyanhydrides of hydrophobic α-amino acids. The synthesized amphiphilic block copolymers were carefully analyzed using a set of different physico-chemical methods to establish their composition and molecular weight. The developed amphiphilic copolymers tended to self-assemble in nanoparticles of different morphology that depended on the nature of the hydrophobic amino acid present in the copolymer. The hydrodynamic diameter, morphology, and cytotoxicity of polymer particles based on PMAG-b-PAA were evaluated using dynamic light scattering (DLS) and transmission electron microscopy (TEM), as well as CellTiter-Blue (CTB) assay, respectively. The redox-responsive properties of nanoparticles were evaluated in the presence of glutathione taken at different concentrations. Moreover, the encapsulation of paclitaxel into PMAG-b-PAA particles and their cytotoxicity on human lung carcinoma cells (A549) and human breast adenocarcinoma cells (MCF-7) were studied.

Synthesis of siRNA Polyplexes Adopting a Combination of RAFT Polymerization and Thiol-ene Chemistry

2009 ◽  
Vol 62 (10) ◽  
pp. 1344 ◽  
Author(s):  
David Valade ◽  
Cyrille Boyer ◽  
Thomas P. Davis ◽  
Volga Bulmus
Keyword(s):  
Block Copolymers ◽  
High Efficiency ◽  
Raft Polymerization ◽  
Hydrodynamic Diameter ◽  
Small Interfering Rnas ◽  
Buffer Solution ◽  
Polyelectrolyte Complexes ◽  
Reversible Addition ◽  
Hydroxypropyl Methacrylamide ◽  
Cationic Copolymers

Block copolymers of allyl methacrylate and N-(2-hydroxypropyl)methacrylamide (HPMA) with different block lengths have been synthesized by reversible addition–fragmentation chain transfer polymerization. Allyl groups were modified with cysteamine, via a thiol-ene photoreaction, with a high efficiency (~100%) as evidenced by NMR spectroscopy, yielding cationic copolymers of HPMA. Polyelectrolyte complexes of small interfering RNAs (siRNA) and the cationic block copolymers were then formed at an N/P ratio between 1 and 4 depending on the block length of the copolymers. Increasing the length of the hydrophilic block was found to decrease the efficiency of siRNA complexation. The hydrodynamic diameter of the polyplexes in 130 mM buffer solution was less than 100 nm.

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