Search results for "Polymers"

Rapid Synthesis and MALDI-ToF Characterization of Poly(ethylene oxide) Multiarm Star Polymers

2009

Multiarm PEO star polymers with a purely aliphatic polyether structure have been synthesized using hyperbranched polyglycerol (PG) with different molecular weights as a multifunctional initiator. Different degrees of deprotonation of the initiator were studied with respect to molecular weight control. The results show that the degree of deprotonation is a crucial parameter for the synthesis of well-defined polymers with controlled molecular weights. Partial deprotonation of the PG hydroxyl groups (5-8%) was proven to represent an optimum for the synthesis of star polymers with molecular masses close to the theoretical values. Molecular weights of the stars ranged between 9 000 and 30000g · …

Microstructure analysis of biocompatible phosphoester copolymers

2013

Copolymers with varying compositions of 2-ethoxy-2-oxo-1,3,2-dioxaphospholane (EEP) and 2-ethoxy-4-methyl-2-oxo-1,3,2-dioxaphospholane (EMEP) have been synthesized via 1,5,7-triazabicyclo[4.4.0]dec-5-ene-catalyzed anionic ring-opening polymerization. The molecular weights and comonomer ratios were well controlled and polymers with reasonable molecular weight distributions (<1.5) were obtained in all cases. The copolymers were investigated by 1H and 31P NMR spectroscopies to determine the underlying microstructure via detailed dyad analysis. The copolymers were found to be nontoxic to HeLa cells. Furthermore, the obtained copolymers of EEP and EMEP show thermoresponsive properties, i.e., exh…

1996

Developing an artificial oxygen carrier for use in humans, we polymerize native haemoglobin and myoglobin, using bifunctional, amino group specific cross-linkers, to soluble, so-called hyperpolymers. These polymers, like other polymerized globular proteins, are members of a new class of macromolecues which consist of macromolecular base units. They all have, due to the mechanisms of the chemical reaction, broad distributions of molecular weights. Fractions of hyperpolymers of human haemoglobin were obtained by employing preparative gel-permeation (size-exclusion) chromatography. The calibration curve of analytical gel-permeation chromatography (GPC) for haemoglobin hyperpolymers was determi…

Hyperbranched Polyglycerols with Elevated Molecular Weights: A Facile Two-Step Synthesis Protocol Based on Polyglycerol Macroinitiators

2009

Hyperbranched polyglycerol (PG) is established as one of the few hyperbranched polymers that offer the possibility to control molecular weight up to Mn = 6000 g/mol. This work introduces a facile 2-step strategy that relies on the use of a low molecular weight PG (Mn = 500 and 1000 g/mol) as a macroinitiator for the slow addition of glycidol, permitting to overcome previous limitations concerning molecular weights and molecular weight control. A systematic investigation of the effect of the degree of deprotonation on the control of the polymerization reaction has been carried out. A series of hyperbranched PGs with molecular weights up to Mn = 24000 g/mol has been obtained under fully contr…

Poly(phosphonate)-mediated Horner–Wadsworth–Emmons reactions

2015

A novel, general protocol for a polymer-mediated Horner–Wadsworth–Emmons (HWE) reaction is reported. The polyvalent polymeric reagent was prepared via acyclic diene metathesis (ADMET) polymerization. Homo- and copolymers of reactive poly(phosphonate)s with molecular weights up to 40 000 g·mol−1 and molecular weight dispersities Đ < 2 were successfully synthesized. Subsequent application of these polymers in the HWE reaction to prepare a library of aromatic α,β-unsaturated ketones (chalcons) has proven to be an efficient synthetic pathway to minimize purification efforts, as the polymeric side-product can be removed by simple precipitation. In this paper we also demonstrate for the first tim…

Artifacts in Light Scattering Experiments Using Opaque Scattering Screens on the Example of Spinodal Decomposition

1996

New aromatic diamines containing a multiring flexible skeleton for the synthesis of thermally stable polyimides

2000

Abstract Multi-ring aromatic diamines bearing a long alkyl chain (C 6 , C 8 or C 16 ) were obtained from the corresponding dinitro compounds synthesized by a Friedel–Crafts alkylation of substituted mesitylenes by paranitrobenzyl chloride. The bismaleimide synthesized from the diamine bearing a C 16 chain formed a thermostable polyimide.

RAFT-polymerized poly(hexafluoroisopropyl methacrylate)s as precursors for functional water-soluble polymers

2014

Post-polymerization modification of well-defined precursor polymers is a versatile tool to obtain multifunctional water-soluble polymers that cannot be synthesized by common polymerization techniques. For the first time, 1,1,1,3,3,3-hexafluoroisopropyl methacrylate (HFIPMA) based homo and block copolymers were synthesized via RAFT polymerization to provide precise precursors for the post-polymerization modification of the 1,1,1,3,3,3-hexafluoroisopropyl ester side chains with water-soluble amines (methoxy tri(ethylene glycol) amine, 2-hydroxypropyl amine and 3-(dimethylamino)-1-propylamine). Sequential aminolysis using Oregon Green cadaverine first followed by 2-hydroxypropyl amine enables …

Evaluating chemical ligation techniques for the synthesis of block copolypeptides, polypeptoids and block copolypept(o)ides: a comparative study

2015

In this work, we describe the synthesis of block copolypeptides, polypeptoids and block copolypept(o)ides by chemical ligation techniques. Polysarcosine (PSar), poly(N-e-trifluoroacetyl-L-lysine) (PLys(TFA)) and poly(γ-benzyl-L-glutamate) (PGlu(OBzl)) homopolymers of different polarities and end group functionalities but with similar average degrees of polymerization (Xn = 50 and 100) could be obtained by ring opening polymerization (ROP) of α-amino acid N-carboxyanhydrides (NCA) and postpolymerization modification reactions. In the next step, these polymers were applied to copper(I)-catalyzed azide–alkyne coupling (CuAAC), strain-promoted azide–alkyne coupling (SPAAC) and native chemical l…

Cationic copolymers of ?,?-poly-(N-2-hydroxyethyl)-DL-aspartamide (PHEA) and ?,?-polyasparthylhydrazide (PAHy): synthesis and characterization

2000

In the present study the derivatization of two water-soluble synthetic polymers, α,β-poly(N-2-hydroxyethyl)-DL-aspartamide (PHEA) and α,β-polyasparthylhydrazide (PAHy), with glycidyltrimethylammonium chloride (GTA) is described. This reaction permits the introduction of positive charges in the macromolecular chains of PHEA and PAHy in order to make easier the electrostatic interaction with DNA. Different parameters affect the reaction of derivatization, such as GTA concentration and reaction time. PHEA reacts partially and slowly with GTA; on the contrary the reaction of PAHy with GTA is more rapid and extensive. The derivatization of PHEA and PAHy with GTA is a convenient method to introdu…