Search results for "Living polymerization"

Macromonomers on the basis of 2-phenyl-2-oxazoline

1988

By initiation of the ring-opening polymerization of 2-phenyl-2-oxazoline (1) with p-iodomethylstyrene a macromonomer with a styrene end-group (2) is obtained. The degree of polymerization was varied between 10 and 16. The radical copolymerization of 2 with styrene is described. 1 forms with methyl triflate a very stable oxazolinium salt which is a good initiator for the bulk polymerization of 1 at temperatures of 50–70°C. It was conclusively proved that under these conditions the polymerization proceeds by a living mechanism. By termination with N, N-dimethylaminopropylmeth-acrylamide a macromonomer (5) was obtained. 5 can be radically homopolymerized. This comb-like polymer 6 has the typic…

An All-ROMP Route to Graft Copolymers

2007

A new versatile synthesis strategy for macromonomers has been developed that uses the living ring-opening metathesis polymerization (ROMP) with commercial Grubbs first generation ruthenium initiators. Homopolymers as well as diblock copolymers were end-functionalized with norbornene derivatives to serve as macromonomers. The graft copolymerization of the macromonomers was also carried out employing ROMP. Well-defined and highly functional graft copolymers are accessible by this new synthetic route.

RAFT Polymerization of Pentafluorophenyl Methacrylate: Preparation of Reactive Linear Diblock Copolymers

2005

Reversible addition fragmentation chain transfer (RAFT) polymerization of pentafluorophenyl methacrylate (PFMA) was carried out in the presence of cumyldithiobenzoate and 4-cyano-4-((thiobenzoyl)sulfanyl)pentanoic acid, respectively. These chain transfer agents with 2,2'-azoisobutyronitrile (AIBN) as initiator yielded the active ester polymer poly(PFMA) with M n up to 17000 g . mol -1 and low polydispersity index (M w /M n <1.2). Kinetic analysis using 19 F NMR spectroscopy and gel permeation chromatography (GPC) measurements showed controlled polymerization behavior for both chain transfer agents. Successful preparation of linear diblock copolymers consisting of an active ester block and m…

One-pot synthesis and characterization of aliphatic poly(oxytetramethylene) ionene

2002

Abstract One-pot synthesis of poly(oxytetramethylene) ionene (POI) composed of one dimethylammonium group in each repeating unit is described. POI was prepared by using the cationic polymerization of tetrahydrofuran, followed by the chain extension reaction of living poly(oxytetramethylene) (POTM) chain with N , N -dimethylaminotrimethylsilane. The weight average molecular weight of the ionene with bromide counter-anion (POI–Br) was 48,000 g/mol and the molecular weight of POTM between the ionic sites was ca. 2100. POI–Br showed polyelectrolyte behavior in polar solvent. The elastomeric film of POI–Br was prepared: its tensile strength at break and elongation at break were ca. 11 MPa and ca…

Tailored Semiconducting Polymers: Living Radical Polymerization and NLO-Functionalization of Triphenylamines

2002

This paper describes the preparation of various polymers with triarylamine side groups. High molecular weight materials were obtained by free radical polymerization utilizing the gel effect. Polymers with a marrow polydispersity and a predetermined molecular weight could be prepared by living radical polymerization. The T g could, thereby, be controlled between 50 and 140°C either by using different monomers or by varying the molecular weight. Living radical polymerization allowed in addition the preparation of block copolymers. The triarylamine side groups could be transformed into NLO-chromophores by reaction with tetracyanoethylene. This leads to the incorporation of tricyanoethylene. Th…

Cyclodextrins in Polymer Synthesis:  Free-Radical Polymerization of Methylated β-Cyclodextrin Complexes of Methyl Methacrylate and Styrene Controlled…

2000

Kinetic Analysis of “Living” Polymerization Systems Exhibiting Slow Equilibria. 3. “Associative” Mechanism of Group Transfer Polymerization and Ion P…

1996

The averages of the molecular weight distribution are derived for a “living” polymerization process which proceeds via active and “dormant” species and where the active species are formed by addition of a catalyst to a “dormant” species. Such a mechanism is applicable to group transfer and “living” cationic polymerizations (assuming that ion pairs are formed exclusively in the latter case). Both equilibrium and nonequilibrium initial conditions are used for the calculation. The results are very similar to those obtained for degenerative transfer (i.e., direct exchange of activity between active and “dormant” species). The dominating parameter is β = k2/(kpI0), where k2 and kp are the rate c…

Mechanism of Anionic Polymerization of (Meth)acrylates in the Presence of Aluminium Alkyls IV. Formation of a Co-ordinative Polymer Network via the L…

1996

The polymerization of methyl methacrylate in the presence of aluminium alkyls in toluene deviates from conventional kinetics. This results predominantly from the formation and precipitation of a co-ordinative polymer gel or network. Due to the lower reactivity and accessibility of the living chains in the gel, they are regarded as ’dormant’ and thus the concentration of active species decreases during polymerization. The network formation occurs via co-ordination of the living aluminate chain end group with in-chain ester carbonyl groups. Part of the chains are deactivated by a termination process but they are free of cyclic β-ketoesters which would result from the common ’back-biting’ reac…

Polymerization of styrene

1979

Novel initiating systems for the living polymerization of acrylates and methacrylates

1998

The polymerization of methyl methacrylate with lithiated initiators in the presence of aluminium alkyls in toluene has living character but it deviates from conventional first-order kinetics and the polymers have fairly broad molecular weight distributions. This results from the formation and precipitation of a coordinative polymer network in which the lithium ions of the living chain ends are coordinated to the in-chain ester carbonyl groups. Thus, the network formation can be prevented by adding Lewis bases like methyl pivalate which coordinate to the living chain ends instead ofthe polymer. Alternatively, one can introduce tetraalkylammonium salts aiming at an exchange of the lithium ion…