The role of the molecular weight in crystallization and melt memory poly(ε-caprolactone) (PCL) was investigated. To this end, 10 PCL samples synthetic commercial origin different chain ends, covering a number-average (Mn) range between 0.48 70.5 kg/mol, were analyzed. Polarized light optical microscopy, differential scanning calorimetry, small-angle X-ray scattering (SAXS) employed for in-depth characterization. thermal transitions, morphology, kinetics, structural parameters, effects...

Abstract We describe the organocatalytic depolymerization of poly(ethylene terephthalate) (PET), using a commercially available guanidine catalyst, 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene (TBD). Postconsumer PET beverage bottles were used and processed with 1.0 mol % (0.7 wt %) TBD excess amount ethylene glycol (EG) at 190 °C for 3.5 hours under atmospheric pressure to give bis(2‐hydroxyethyl) terephthalate (BHET) in 78% isolated yield. The catalyst efficiency was comparable other metal...

Sowing the seeds: A simple strategy based on self-seeding allows large single crystals of long regioregular poly(3-hexylthiophene) chains to be grown from solution. When appropriately crystallized, materials differing in their degrees regioregularity and molecular weights formed monoclinic form II with interdigitated hexyl side groups (see picture). Detailed facts importance specialist readers are published as "Supporting Information". Such documents peer-reviewed, but not copy-edited or...

3D patterning by means of probe-assisted thermal decomposition has been achieved on phthalaldehyde polymer films with 1 nm vertical resolution and 40 lateral resolution. Highly efficient is enabled a self-amplified depolymerization mechanism. Pixel writing speeds the order microseconds are demonstrated.

Aliphatic polycarbonates are often referenced for their interesting applications due to lower tendency undergo hydrolysis, Tg, and degradation in renewable resources. Their synthesis is described using a series of metal-free catalysts allowing preparation well-defined polymers terms molecular weights structures. Additionally, some highlights regarding biomedical such as drug targeting presented.

Catalysts are commonly used in polymer synthesis. Traditionally, catalysts to be metallic compounds but some studies have pointed out their toxicity for human health and environment, the removal of metal impurities from synthetic is quite expensive. Organocatalysts been intensively synthesized now widely ring-opening polymerization (ROP) reactions address these issues. However, most them, there not any evidence safety. The present study attempts assess whether well-established organo-based...

Despite significant advances in organocatalysis, stereoselective polymerization reactions utilizing chiral organocatalysts have received very little attention, and much about the underlying mechanisms remains unknown. Here, we report that both commercially available (R,R)- (S,S)-enantiomers of thiourea-amine Takemoto's promote efficient control high isoselectivity at room temperature ring-opening (ROP) racemic lactide by kinetic resolution, yielding highly isotactic, semicrystalline...

Abstract Since the time first synthetic macrocycles were observed as academic curiosities, great advances have been made. Thanks to development of controlled polymerization processes, new catalytic systems and characterization techniques during last decades, well‐defined cyclic polymers are now readily accessible. This further permits determination their unique set properties, mainly due lack chain ends, use for industrial applications can be foreshadowed. review aims give an overview on...

Alcohol adducts of the N-heterocyclic carbene, 1,3,4-triphenyl-4,5-dihydro-1H-1,2-triazol-5-ylidene (NHC), function as excellent single-component catalyst/initiators for ring-opening polymerization lactide and β-butyrolactone. Their reversible dissociation at elevated temperatures generates alcohol triazolylidene carbene to provide a facile entry cyclic esters on demand. Under optimum conditions, adverse transesterification reactions are minimized, importantly, upon complete consumption...

It's all about control: Alcohol adducts of stable N-heterocyclic carbenes function as excellent single-component catalysts/initiators for the ring-opening polymerization lactide (see scheme). This can be reversibly terminated simply by modulating temperature. The use multifunctional macroinitiators enables synthesis more complex polymer architectures. Supporting information this article is available on WWW under http://www.wiley-vch.de/contents/jc_2002/2005/z500723_s.pdf or from author....

Abstract Verwechslung ausgeschlossen : Ein Wasserstoffbrückenmotiv, das auf hexafluorierten Alkoholfunktionen beruht (siehe Bild; rot O, gelb F), aktiviert elektrophile Substrate. Die katalytische Aktivität des Systems wurde an der Ringöffnungspolymerisation einer Vielzahl gespannter Heterocyclen demonstriert. Polymere mit vorhersagbarem Molekulargewicht, niedriger Polydispersität und verlässlichen Endgruppen wurden erhalten. magnified image

Ring closure click chemistry methods have been used to produce cyclic c-PLLA and c-PDLA of a number-average molecular weight close 10 kg/mol. The effects stereochemistry the polymer chains their topology on structure, nucleation, crystallization were studied in detail employing wide-angle X-ray scattering (WAXS), small-angle (SAXS), polarized light optical microscopy (PLOM), standard advanced differential scanning calorimetry (DSC). crystal structures linear PLAs are identical each other, no...

ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTProbe-Based Nanolithography: Self-Amplified Depolymerization Media for Dry LithographyOlivier Coulembier†, Armin Knoll‡*, David Pires‡, Bernd Gotsmann‡, Urs Duerig‡, Jane Frommer§, Robert D. Miller§, Philippe Dubois†, and James L. Hedrick§*View Author Information† Laboratory of Polymeric Composite Materials, Center Innovation Research in Materials Polymers (CIRMAP), University Mons, Place du Parc 23, 7000 Belgium‡ IBM Zurich Laboratory, Säumerstrasse...

The ability of ICl₃ to activate electrophilic substrates through halogen bonding and its catalytic activity towards the ring-opening polymerization L-lactide is demonstrated in this communication. Association techniques highlights production narrowly dispersed PLA predictable molecular weights from commercially available molecule.

Abstract Nowadays, numerous experimental and theoretical studies are devoted to the research field of polythiophenes other electroconjugated polymers due huge potentialities those conducting polymers. Synthetic procedures now developed reach highest control over both polymerization analytical methodologies allowing an in‐depth straightforward characterization polymer samples without any required doubt. Mass spectrometry in particular MALDI‐ToF measurements definitively suitable meet...

A polylactide-block-(dimethyl β-malic acid-co-β-butyrolactone)-block-polylactide (PLA-b-P(dMMLA-co-BL)-b-PLA) triblock copolymer has been synthesized according to a totally original three-step strategy. In first step, the ring-opening polymerization (ROP) of dimethyl benzyl β-malolactonate (dMMLABz) and β-butyrolactone (BL) carried out in toluene/t-BuOH solvent mixture at 80 °C by using ethylene glycol as initiator commercially available 1,3,4-triphenyl-4,5-dihydro-1H-1,2,4-triazol-5-ylidene...

Abstract Well‐defined amphiphilic PCL‐ b ‐PDMAEMA block copolymers were successfully synthesized by a combination of ATRP and “click” chemistry following either commutative two‐step procedure or straightforward one‐pot process using CuBr · 3Bpy as the sole catalyst. Compared to traditional coupling method, combining click even in “one‐pot” allows preparation diblock characterized narrow molecular weight distribution quantitative conversion azides alkynes into triazole functions. Moreover,...

Novel well-defined amphiphilic poly(d-lactide)-b-poly(N,N-dimethylamino-2-ethyl methacrylate) (PDLA-b-PDMAEMA) and poly(l-lactide)-b-poly(N,N-dimethylamino-2-ethyl (PLLA-b-PDMAEMA) copolymers were obtained. The synthesis strategy consisted of a three-step procedure: (i) controlled ring-opening polymerization (ROP) (d- or l-)lactide initiated by Al(OiPr)3, followed (ii) quantitative conversion the polylactide (PLA) hydroxyl end-groups with bromoisobutyryl bromide (iii) atom transfer radical...