Two-arm PCL and PLLA macrophotoinitiators with benzoin end-functional groups by combination of ROP and click chemistry and their use in the synthesis of A2B2 type miktoarm star copolymers

Crystallization, thermal and mechanical properties of stereocomplexed poly(lactide) with flexible PLLA/PCL multiblock copolymer

In this work, the synthesized PLLA/PCL multi-block copolymers with different compositions were introduced into a stereocomplexed poly(lactide) (sc-PLA) matrix to accelerate the stereocomplexation of PLA enantiomers and improve its inherent brittleness. The PLLA/PCL multi-block copolymers were in different compositions to adjust the molecular weight of the PLLA block. The structure, molecular weight, crystallization behavior, crystal structure and thermal stability of PLLA/PCL multi-block copolymers were investigated. The results indicated that PLLA/PCL multi-block copolymers with controllable structure and composition were successfully synthesized. On this basis, the blends of sc-PLA and PLLA/PCL multi-block copolymers were prepared by solution casting, and characterized. The results revealed that the introduction of PLLA/PCL multi-block copolymers promoted the stereocomplexation of the PLA enantiomers during the melting crystallization process to obtain a complete stereocomplexed material. But the presence of the PCL block leads to a decrease in the melting temperature of the stereocomplex and difficulty in homogeneous nucleation. Compared with sc-PLA, the elongation at break of the blends was significantly improved and their tensile strengths were only slightly reduced. And the thermal stability and mechanical properties of the blends could be adjusted by controlling the content and composition of PCL/PLLA multi-block copolymers. These results revealed that the degree of stereocomplexation and toughness of sc-PLA were improved, which may expand the application fields of PLA-based materials.

The PLLA/PCL multi-block copolymer was introduced into the stereocomplexed PLA matrix, and its effect on the crystallization, thermal and mechanical properties of the stereocomplexed PLA was discussed.

3,4-Ethylenedioxythiophene (EDOT) End-Group Functionalized Poly-ε-caprolactone (PCL): Self-Assembly in Organic Solvents and Its Coincidentally Observed Peculiar Behavior in Thin Film and Protonated Media

End-group functionalization of homopolymers is a valuable way to produce high-fidelity nanostructured and functional soft materials when the structures obtained have the capacity for self-assembly (SA) encoded in their structural details. Herein, an end-functionalized PCL with a π-conjugated EDOT moiety, (EDOT-PCL), designed exclusively from hydrophobic domains, as a functional "hydrophobic amphiphile", was synthesized in the bulk ROP of ε-caprolactone. The experimental results obtained by spectroscopic methods, including NMR, UV-vis, and fluorescence, using DLS and by AFM, confirm that in solvents with extremely different polarities (chloroform and acetonitrile), EDOT-PCL presents an interaction- and structure-based bias, which is strong and selective enough to exert control over supramolecular packing, both in dispersions and in the film state. This leads to the diversity of SA structures, including spheroidal, straight, and helical rods, as well as orthorhombic single crystals, with solvent-dependent shapes and sizes, confirming that EDOT-PCL behaves as a "block-molecule". According to the results from AFM imaging, an unexpected transformation of micelle-type nanostructures into single 2D lamellar crystals, through breakout crystallization, took place by simple acetonitrile evaporation during the formation of the film on the mica support at room temperature. Moreover, EDOT-PCL's propensity for spontaneous oxidant-free oligomerization in acidic media was proposed as a presumptive answer for the unexpected appearance of blue color during its dissolution in CDCl3 at a high concentration. FT-IR, UV-vis, and fluorescence techniques were used to support this claim. Besides being intriguing and unforeseen, the experimental findings concerning EDOT-PCL have raised new and interesting questions that deserve to be addressed in future research.

Photoinduced free radical promoted cationic polymerization 40 years after its discovery

Free radical promoted cationic photopolymerization has been described with its historical background, main principles and usage in polymer synthesis.

Highly efficient UV-Vis light activated three-component photoinitiators composed of tris(trimethylsilyl)silane for polymerization of acrylates

The goal of this paper concerns the evaluation of the efficiency of novel three-component systems for initiating the photopolymerization process of 2-ethyl-2-(hydroxymethyl)-1,3-propanediol triacrylate (TMPTA).

Synthesis of miktoarm star-shaped and inverse star-block copolymers by a combination of ring-opening polymerization and click chemistry

Based on the combination of the “arm-first” and “core-first” strategies, the miktoarm star-shaped copolymer PLLA2PCL2 and the inverse star-block copolymer (PCL-b-PLLA)2-core-(PCL-b-PLLA)2 were designed and synthesized by the combination of ring-opening polymerization (ROP) and a click reaction. The miktoarm star-shaped copolymer PLLA2PCL2 was synthesized by a click reaction of an azido macroinitiator PLLA2(N3)2 and HC≡C-PCL. The inverse star-block copolymer (PCL-b-PLLA)2-core-(PCL-b-PLLA)2 was synthesized by a click reaction of an azido macroinitiator (PCL-b-PLLA)2(N3)2 and HC≡C-PCL-b-PLLA. The structures of these star polymers were confirmed by nuclear magnetic resonance (NMR), Fourier-transform infrared (FT-IR) spectroscopy and gel permeation chromatograph (GPC). The inverse star-block copolymer could be used to study the potential relationship between polymer structure and properties, which has a unique structure and good crystallization properties.

Synthesis and in vitro study of modified chitosan-polycaprolactam nanocomplex as delivery system

In this work, chitosan/polycaprolactam (PCL-CS) nano-complex was synthesized and their micelles were formed as self-assembled amphiphilic nano-compartments. These micelles were utilize for drug delivery after loading quercetin (QU) as chemotherapeutic agent and delivery potency of this nano-complex was investigated. This nano-complex was also functionalized with folic acid (FA) in order to targeting delivery of nano-carrier to cancer cell lines. This foure dimensional nano-complex was successfully characterized based on UV-vis, FT-IR, DLS, and TGA analytical devices to confirm the synthesis. Drug loading was estimated 21.5% in final nano-carrier. In vitro drug release study was applied to investigation of QU release in PBS that was exhibited high potency of nano-complex in controlled drug release. Cell viability of assay was implemented to determination of biocompatibility, bioavailability and therapeutic potency of nano-complexes on different cancer and normal cell lines. Micelles demonstrated safety levels for 24 and 48 h post-treatment incubation and FA receptor mediated uptake of chitosan/polycaprolactam/folic acid/quercetin (PCL-CS-FA-QU) was exhibited excellent efficiency on inhibition of cancer cells.

Benzoins and cyclobenzoins in supramolecular and polymer chemistry

Benzoin condensation is one of the oldest rigorously described organic reactions, having been discovered in 1832 by Liebig and Wöhler. This Feature Article summarizes our work on cyclobenzoins: a class of macrocyclic compounds prepared by a benzoin cyclooligomerization of simple aromatic dialdehydes.