Ring-opening polymerization

About: Ring-opening polymerization is a research topic. Over the lifetime, 9499 publications have been published within this topic receiving 281471 citations. The topic is also known as: ROP.

Kinetic Study and New Applications of UV Radiation Curing

Abstract: Highly crosslinked polymers can be readily synthesized by photoinitiated polymerization of multifunctional monomers or functionalized polymers. The reaction can be followed in situ by real-time infrared (RT-IR) spectroscopy, a technique that records conversion versus time curves in photosensitive resins undergoing ultrafast polymerization upon UV exposure. For acrylate-based resins, UV-curing proceeds with long kinetic chains (7700 mol/radical) in spite of the high initiation rate. RT-IR spectroscopy proved very valuable in assessing the influence of various parameters, such as initiation efficiency, chemical structure of the telechelic oligomer, light intensity, inhibitory effect of oxygen, on polymerization kinetics. Interpenetrating polymer networks can be rapidly synthesized by means of UV irradiation of a mixture of difunctional acrylate and epoxy monomers in the presence of both radical and cationic-type photoinitiators. The same UV technology can be applied to crosslink solid polymers at ambient temperature, which bear different types of reactive groups (acrylate and vinyl double bonds, epoxy ring). UV radiation curing has been successfully used to produce within seconds weathering resistant protective coatings, high-resolution relief images, glass laminates and nanocomposites materials. Photoinitiated crosslinking polymerization.

A highly active zinc catalyst for the controlled polymerization of lactide.

Abstract: We report the preparation, structural characterization, and detailed lactide polymerization behavior of a new Zn(II) alkoxide complex, (L1ZnOEt)2 (L1 = 2,4-di-tert-butyl-6-{[(2‘-dimethylaminoethyl)methylamino]methyl}phenolate). While an X-ray crystal structure revealed the complex to be dimeric in the solid state, nuclear magnetic resonance and mass spectrometric analyses showed that the monomeric form L1ZnOEt predominates in solution. The polymerization of lactide using this complex proceeded with good molecular weight control and gave relatively narrow molecular weight distribution polylactide, even at catalyst loadings of <0.1% that yielded Mn as high as 130 kg mol-1. The effect of impurities on the molecular weight of the product polymers was accounted for using a simple model. Detailed kinetic studies of the polymerization reaction enabled integral and nonintegral orders in L1ZnOEt to be distinguished and the empirical rate law to be elucidated, −d[LA]/dt = kp[L1ZnOEt][LA]. These studies also showed ...

Highly stereoelective polymerization of rac-(D,L)-lactide with a chiral schiff's base/aluminium alkoxide initiator

Abstract: A chiral Schiff's base/aluminium alkoxide initiator bearing a ligand derived from R-(+)-1,1′-binaphthyl-2,2′-diamine was synthesized and used for the stereoelective polymerization of rac-(D,L)-lactide. Rather high stereoelectivity is observed: a polymer with 88% enantiomeric enrichment in D units is obtained at 19% conversion. At high conversions a stereocomplex between D- and L-enriched stereocopolymers is formed. The polymerization reaction shows living type features, and narrow molecular weight distributions (Mw/Mn = 1,05–1,30) are obtained up to very high conversions. This indicates that transesterification reactions do not occur significantly with this sterically hindered initiator.