Search results for "ring-opening polymerization"

Polypept(o)ides: Hybrid Systems Based on Polypeptides and Polypeptoids.

2015

Polypept(o)ides combine the multifunctionality and intrinsic stimuli-responsiveness of synthetic polypeptides with the "stealth"-like properties of the polypeptoid polysarcosine (poly(N-methyl glycine)). This class of block copolymers can be synthesized by sequential ring opening polymerization of α-amino acid N-carboxy-anhydrides (NCAs) and correspondingly of the N-substituted glycine N-carboxyanhydride (NNCA). The resulting block copolymers are characterized by Poisson-like molecular weight distributions, full end group integrity, and dispersities below 1.2. While polysarcosine may be able to tackle the currently arising issues regarding the gold standard PEG, including storage diseases i…

PEG-based Multifunctional Polyethers with Highly Reactive Vinyl-Ether Side Chains for Click-Type Functionalization

2011

Introduction of highly reactive vinyl ether moieties along a poly(ethylene-glycol) (PEG) backbone has been realized by copolymerization of the novel epoxide monomer ethoxy vinyl glycidyl ether (EVGE) with ethylene oxide (EO). A series of copolymers with varying structure (block and random) as well as EVGE comonomer content (5-100%) with molecular weights in the range of 3,900-13,200 g/mol and narrow molecular weight distributions (M-w/M-n = 1.06-1.20) has been synthesized and characterized with respect to their microstructure and thermal properties. The facile transformation of the vinyl ether side chains in click type reactions was verified by two different post polymerization modification…

Amphiphilic Linear-Hyperbranched Block Copolymers with Linear Poly(ethylene oxide) and Hyperbranched Poly(carbosilane) Block

2008

The synthesis of amphiphilic linear-hyperbranched block copolymers with a linear poly(ethylene oxide) (PEO) segment and a hyperbranched poly(carbosilane)s (PCS) block in a rapid three-step strategy is described, combining oxyanionic polymerization with carbosilane chemistry. A linear precursor block copolymer was synthesized via anionic polymerization of allyl glycidyl ether onto a commercial hydroxyl-terminated PEO, using its cesium alkoxide as macro-initiator. The resulting linear AB or ABA-type di- or triblock copolymers serve as polymer cores for the subsequent hydrosilylation polyaddition of an AB2-type carbosilane monomer. Di(allyl)methylsilane or methyldi(undec-10-enylsilane) were em…

Synthesis and properties of amphiphilic “dumbbell”-shaped grafted block copolymers, 1. Anionic synthesis via a polyfunctional initiator

1994

Two poly(ethylene oxide) stars linked by a long polystyrene chain represent a novel amphiphilic architecture (dumbbell), which is available by anionic grafting of ethylene oxide from a hydroxylated polybutadiene-block-polystyrene-block-polybutadiene triblock copolymer. The short butadiene end-blocks (DPB = 36) of a BSB triblock copolymer with a long styrene middle block (DPS = 650) was first modified by hydroboration and oxidation. A multifunctional alkoxide initiator is thus prepared by titration of the hydroxyl groups of the “polybutadiene” end-block with cumylpotassium. Gelation and precipitation of the polyfunctional initiator in THF could be avoided by complexing the cation (K+) with a…

Synthesis and characterization of amphiphilic comb-polymers via ring-opening metathesis polymerization of exo,exo-5,6-bis(alkoxymethyl)-7-oxabicyclo[…

1994

A number of exo,exo-5,6-bis(alkoxymethyl)-7-oxabicyclo[2.2.1]hept-2-enes (exo,exo-5,6-bis(alkoxymethyl)-7-oxanorbornenes) with long alkyl chains were prepared by reduction of the Diels-Alder adduct of furan and maleic anhydride, followed by alkylation with a series of different n-alkylbromides. These monomers were polymerized via ring-opening metathesis polymerization (ROMP) catalyzed by ruthenium trichloride in ethanolic solution. Contrary to a helical conformation as it was predicted by a previous molecular model study the poly(7-oxanorbornenes) adopt a coil conformation in solution. In bulk the materials show side chain crystallization.

Lanthanides benzimidinates: initiators or real catalysts for theɛ-caprolactone polymerization

2000

Synthesis and Characterization of Poly(glyceryl glycerol) Block Copolymers

2008

Inimer-Promoted Synthesis of Branched and Hyperbranched Polylactide Copolymers

2009

A series of (hyper)branched poly(l-lactide)(PLLA) copolymers has been prepared by ring-opening multibranching copolymerization of l-lactide with a hydroxyl-functional (ABB′) lactone inimer, 5HDON (5-hydroxymethyl-1,4-dioxane-2-on). Polymerization was conducted in bulk and solution and catalyzed either by stanneous-2-ethyl hexanoate (Sn(Oct)2) or an organic base, 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD). Precise structural characterization of the resulting branched copolyester structures was accomplished by a combination of 2D NMR techniques, relying on the comparison with model compounds. The 5HDON inimer was employed in 1% to 20% fractions and is incorporated either as a dendritic unit or…

Phenoxyamidine Zn and Al Complexes: Synthesis, Characterization, and Use in the Ring-Opening Polymerization of Lactide

2019

International audience; Herein we report the synthesis of new ditopic ligands, which consist of a phenoxy group and N,N,N'trisubstituted amidines linked by a methylene spacer (L1-L4). Their coordination chemistry has been studied/investigated with Zn(II) and Al(III). Alkane elimination route between the phenol-amidine proligands (L1H-L4H) and Et2Zn led to dinuclear complexes [(L1-L4)ZnEt]2 (1a-4a) in which the Zn centers are chelated by phenoxyamidine ligands and bridged through the oxygen atom of the phenoxy groups. Salt metathesis reaction between two equivalents of the sodium amidine phenate L1Na and ZnCl2 led to a bis-chelate chiral spiro-complex (L12Zn) 1a'. Analogous alkane eliminatio…

A head-to-head comparison of poly(sarcosine) and poly(ethylene glycol) in peptidic, amphiphilic block copolymers

2015

Abstract In this work we compare chemical and solution properties, like critical aggregate concentrations (CAC) and hydrodynamic radii of aggregates based on either poly(ethylene glycol) or poly(sarcosine) block copolymers in aqueous solution. The amine functionalized, hydrophilic polymers poly(sarcosine) (degree of polymerization, X n  = 100 and 200) and PEG (X n  = 121 and 242) of comparable hydrodynamic volume were used to initiate the ring opening polymerization of α-amino acid- N -carboxyanhydrides based on ɣ-benzyl- l -glutamate (Glu(OBn)) or e-carboxybenzyl- l -lysine (Lys(Z)). The second, hydrophobic block was kept at a degree of polymerization of 25 and 50 to enable a direct compar…