An All‐ROMP Route to Graft Copolymers

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.

     

Oriented Synthesis of One‐Dimensional Polypyrrole Molecule Chains in a Metal‐Organic Framework

We report for the first time the preparation of single polypyrrole (PPy) molecule chains using a “metal‐organic framework” with 1 nm channels as a template. The obtained one‐dimensional (1‐D) PPy has highly structure order and excellent conductivity, which has improved by as much as five orders of magnitude in comparison with that of 2‐D PPy.

     

Preparation of Ag‐Embedded Polystyrene Nanospheres and Nanocapsules by Miniemulsion Polymerization

An isopropyl myristate (IPM) biocompatible oil and an IPM solution of dodecanethiol‐capped Ag nanoparticles (NPs, 4.5 nm) were used as hydrophobes to suppress the Ostwald ripening of monomer/hydrophobe miniemulsified droplets in a surfactant‐stabilized water phase. The formation of non‐IPM‐encapsulated nanospheres (48 nm) and IPM‐encapsulated nanocapsules (90 nm) were precisely controlled by using a water‐soluble and an oil‐soluble initiator, respectively, in the presence of a pure IPM as a hydrophobe in miniemulsion polymerization. Well‐defined PS nanospheres, on which surfaces were coated with Ag NPs (Ag/PS nanospheres, 65 nm), and nanocapsules encapsulating both NPs and IPM liquid phase (Ag‐IPM/PS nanocapsules, 115 nm) were made by replacing the hydrophobe from pure IPM with Ag/IPM solution. These nanostructures were characterized by transmission and scanning electron microscopes.

     

A Versatile and Efficient Hydrosilylation Route to Functionalized Polyferrocenylsilanes

Summary: The synthesis of a series of polyferrocenylsilanes (PFSs) containing CC functionalities in the side‐group structure and their subsequent derivatization by hydrosilylation chemistry are described. Hydrosilylation is shown to be an effective postpolymerization functionalization method, particularly in the case of poly(ferrocenylmethylvinylsilane), which can be prepared by photolytic anionic ring‐opening polymerization of the corresponding ferrocenophane monomer.

     

Encapsulation of Bovine Serum Albumin in Temperature‐Programmed “Shell‐in‐Shell” Structures

A novel approach to load a hydrophilic bovine serum albumin into drug carriers was proposed in terms of temperature‐programmed “shell‐in‐shell” structures, which were fabricated with poly(N‐isopropylacrylamide), poly(lactide), poly(ethylene glycol), and Au nanoparticles. Spherically well‐defined “shell‐in‐shell” structures were constructed by a modified‐double‐emulsion method (MDEM). The lower critical solubility temperature of the structures was manipulated to 36.4 °C which was confirmed by UV/Vis spectroscopy and DSC (Differential Scanning Calorimetry).

TEM image of the Au@PLLA‐PEG@PNIPAAm‐PDLA structure.     

Lewis Acid‐Induced N‐Methyleneamines as Initiators in the Synthesis of Secondary Amine‐Terminated Polymers

Summary: The cationic polymerization of poly(tert‐butyl vinyl ether) using N‐methyleneamine equivalents derived from a Lewis acid/1,3,5‐trimethylhexahydro‐1,3,5‐triazine (TMTA) co‐initiating system is reported. The resulting polymers possessed secondary amine functionality at the chain terminus, verified by derivatization with 4‐chloro‐7‐nitrobenzo‐2‐oxa‐1,3‐diazole (NBD‐Cl) and subsequent analysis with GPC‐UV (470 nm) and ¹H NMR.

Use of N‐methyleneamine equivalents lacking aryl substituents to afford amine‐terminated poly(tert‐butyl vinyl ether).     

Self‐Assembled Single‐Crystal Polyaniline Microplates and Their Anisotropic Electrical Transport Property

Self‐assembly of two‐dimensional (2D) structures from functional molecules is of great scientific importance. Herein, using a typical linear conducting polymer, polyaniline as building blocks, 2D single crystalline microplates are successively produced. The structure of 2D microplates is clearly defined by selected area electron diffraction, X‐ray diffraction, and Raman spectroscopy. Owing to the anisotropic arrangement of linear conjugated PANI molecules, the microplate shows a typical anisotropic electrical transport property.

     

Highly Efficient Synthesis of Low Polydispersity Core Cross‐Linked Star Polymers by Ru‐Catalyzed Living Radical Polymerization

The efficient formation of low polydispersity core cross‐linked star (CCS) polymers via controlled/living radical polymerization (LRP) and the arm‐first approach was found to be dependant on the mediating catalyst system. The Ru catalyst, Ru(Ind)Cl(PPh₃)₂ Cat. 1 , and tertiary amine co‐catalyst were used to synthesize highly living poly(methyl methacrylate) (PMMA) macroinitiators, which were then linked together with ethylene glycol dimethacrylate (EGDMA) to form PMMA_armPEGDMA_core CCS polymers. The quantitative and near‐quantitative synthesis of CCS polymers were observed for low to moderate molecular weight macroinitiators ( = 8 and 20 kDa), respectively. Lower conversions were observed for high‐molecular weight macroinitiators ( ≥ 60 kDa). Overall, an improvement of between 10 and 20% was observed when comparing the Cat. 1 system to a conventional Cu‐catalyzed system. This significant improvement in macroinitiator‐to‐star conversion is explained in the context of catalyst system selection and CCS polymer formation.

     

Three‐dimensional Arrangement of Short DNA Oligonucleotides at Surfaces via the Synthesis of DNA‐branched Polyacrylamide Brushes by SI‐ATRP

Short DNA oligonucleotide branches are incorporated into acrylamide brushes via surface initiated atom transfer radical polymerization in an attempt to increase DNA surface density by building three‐dimensional molecular architectures. ATR‐FTIR as well as hybridization studies followed by SPR confirm the incorporation of the DNA sequences into the polymer backbone. MALDI‐TOF analysis further suggests that six acrylamide monomer units are typically separating DNA branches present on a single brushes approximately 26 units long. This new approach offers a promising alternative to SAM‐based nucleic acid and aptamer sensors and could enable the realization of more complex soft materials of controlled architecture capable of both recognition and signaling by including additional optically or electrochemically active moieties.

     

Synthesis of Well‐Defined Telechelic Aromatic Polyamides by Chain‐Growth Polycondensation: Application to the Synthesis of Block Copolymers of Polyamide and Poly(tetrahydrofuran)

Well‐defined telechelic‐type aromatic polyamides having a secondary amino group and a phenyl ester moiety at each chain end were prepared by the chain‐growth polycondensation of phenyl 4‐(octylamino)benzoate ( 1 ) with initiator 2 (N‐tert‐butoxycarbonylated 1 ), followed by deprotection of the N‐protecting group of the initiator unit. This polycondensation was applied to the synthesis of well‐defined di‐ and triblock copolymers of aromatic polyamides and poly(tetrahydrofuran) (poly(THF)) by the reaction of the terminal secondary amino group of the polyamide with the living cationic propagating group of poly(THF).

Block copolymers of polyamide and poly(tetrahydrofuran).     

Uniform Sub‐Micron Polymer Spheres Coated with Ag Nanoparticles

Summary: The synthesis of well‐defined uniform and spherical sub‐micron polymeric spheres, specifically poly[styrene‐co‐(glycidyl methacrylate)] (PSGMA) with a uniform size distribution and surface chemical functionality, is described. It is shown that the surface can be modified with a multi‐amine functional polymer, polyethyleneimine (PEI), most likely through covalent bonding in addition to electrostatic attraction. The PEI acts both as a stabilizing agent and a complexation agent for the deposition of noble metal Ag nanoparticles.

Reaction of PSGMA samples with excess PEI, and its TEM image.     

Microwave‐Assisted Ring‐Opening Polymerization of ε‐Caprolactone in the Presence of Ionic Liquid

Summary: Microwave‐assisted ring‐opening polymerization of ε‐caprolactone in the presence of 1‐butyl‐3‐methylimidazolium tetrafluoroborate ionic liquid using zinc oxide as a catalyst is investigated. By adding 30 wt.‐% ionic liquid, poly(ε‐caprolactone) with a weight‐average molar mass of 28 500 g · mol⁻¹ is obtained at 85 W for 30 min. The results indicate that the polymerization could be efficiently enhanced in the presence of ionic liquids under microwave irradiation because ionic liquids can effectively absorb microwave energy.

     

Living Cationic Polymerizations Utilizing an Automated Synthesizer: High‐Throughput Synthesis of Polyoxazolines

Living cationic ring‐opening polymerizations of 2‐ethyl‐2‐oxazoline and purification of the resulting polymers were performed utilizing an automated synthesizer. Eight polymers (500 mg scale) as well as 40 polymers (150 mg scale) were synthesized in parallel to investigate the reproducibility and the living character of the polymerizations. The poly(2‐ethyl‐2‐oxazoline)s obtained such were characterized by means of ¹H NMR spectroscopy, MALDI‐TOF mass spectrometry and online gel permeation chromatography.

     

Synthesis of CdSe–Poly(N‐vinylcarbazole) Nanocomposite by Atom Transfer Radical Polymerization for Potential Optoelectronic Applications

A hybrid inorganic–polymer nanocomposite using CdSe nanocrystals with high electron mobility has been successfully synthesized by atom transfer radical polymerization (ATRP). First the hydroxyl‐coated CdSe nanoparticles (i.e., CdSe–OH) were prepared via a wet chemical route. A polymerization initiator was then prepared for ATRP of N‐vinylcarbazole. FT‐IR, ¹H NMR, and XRD analyses confirmed the successful synthesis of CdSe–poly(N‐vinylcarbazole) (PVK) nanohybrid. UV–Vis spectra and photoluminescence data revealed that grafting of PVK onto the surface of CdSe nanocrystals would reduce the band gap of PVK and cause the red shift of emission peak. TEM and SEM micrographs exhibited CdSe nanoparticles that were well‐coated with PVK polymer.

     

Branched Oligovinylcyclopropane by Transfer to Allylic Carbonate Comonomers via Radical Ring‐Opening Polymerization

Summary: Radical copolymerization of 1,1‐bis(ethoxycarbonyl)‐2‐vinylcyclopropane (ECVCP) with allyl carbonates that contain isopropyl groups yields highly branched polyvinylcyclopropanes. The polymerizations were carried out in the presence of 2,2‐azoisobutyronitrile at 150 °C in chlorobenzene. Structural analysis of the polymers suggested that radical ring‐opening polymerization proceeded through 1,5‐ring‐opening followed by transfer to the allylic carbonate comonomers. Intra‐molecular cyclization, which yields polycyclobutane units, was also observed during the polymerization.

Synthesis of branched 1,1‐bis(ethoxycarbonyl)‐2‐vinylcyclopropane by transfer to the isopropoxy functional allyl carbonate comonomers.     

Vapor‐Based Synthesis of Poly[(4‐formyl‐p‐xylylene)‐co‐(p‐xylylene)] and Its Use for Biomimetic Surface Modifications

Summary: The vapor‐based synthesis and characterization of a reactive polymer, poly[(4‐formyl‐p‐xylylene)‐co‐(p‐xylylene)] ( 1 ), have been reported. The reactive polymer coating enables the immobilization of oligosaccharides via the chemoselective aldehyde‐hydrazide coupling reaction.

     

Two‐Photon Pattern Bleaching for Characterizing Structural Changes in Polymer Films

Using two‐photon absorption, an array of spots in a dye‐doped polymer film can be bleached, creating a three‐dimensional structure that can be imaged with two‐photon or confocal microscopy. Microscopic deformations resulting from various treatments to the film can be characterized, for example, swelling or shrinking. This technique is demonstrated on dye‐doped poly(vinyl alcohol), in which the effect of swelling with the addition of water to the film is shown.

     

Laser‐Induced Crosslinking of Ultra‐Low‐ and High‐Density Polyethylene

The use of laser radiation to initiate the crosslinking process in ultra low‐density polyethylene (ULDPE) and high‐density polyethylene (HDPE) was evaluated. The process was found to be most effective for pulsed laser irradiation when the polymer was traced with a photoinitiator: 4‐chlorobenzophenone (CBP). The gel content measurements proved that crosslinking took place in all the irradiated samples. The degree of crosslinking was measured for different values of irradiation energy, temperature, photoinitiator concentration and the nature and type of crosslinking agents. The effects of all these parameters on the degree of crosslinking and the consequent effects on mechanical properties of the polymers were analyzed. Also found in the present study is the fact that a better efficiency of crosslinking was achieved at longer laser irradiation wavelength. The ultimate tensile stress and elongation at fracture were measured for all cross‐linked samples and compared with those of the controlled ones.

     

Plasma‐Initiated Controlled/Living Radical Polymerization of Methyl Methacrylate in the Presence of 2‐Cyanoprop‐2‐yl 1‐dithionaphthalate (CPDN)

Summary: Plasma‐initiated controlled/living radical polymerization of methyl methacrylate (MMA) was carried out in the presence of 2‐cyanoprop‐2‐yl 1‐dithionaphthalate. Well‐defined poly(methyl methacrylate) (PMMA), with a narrow polydispersity, could be synthesized. The polymerization is proposed to occur via a RAFT mechanism. Chain‐extension reactions were also successfully carried out to obtain higher molecular weight PMMA and PMMA‐block‐PSt copolymer.

Dependence of ln([M]₀/[M]) on post‐polymerization time (above), and \overline M _{\rm n} and PDI against conversion (below) for plasma initiated RAFT polymerization of MMA at 25 °C.     

Self‐Assembly of Large Multimolecular Micelles from Hyperbranched Star Copolymers

This work focused on the synthesis and aqueous self‐assembly of a series of novel hyperbranched star copolymers with a hyperbranched poly[3‐ethyl‐3‐(hydroxymethyl)oxetane] (HBPO) core and many linear poly[2‐(dimethylamino)ethyl methacrylate] (PDMAEMA) arms. The copolymers can synchronously form unimolecular micelles (around 10 nm) and large multimolecular micelles (around 100 nm) in water at room temperature. TEM measurements have provided direct evidence that the large micelles are a kind of multimicelle aggregates (MMAs) with the basic building units of unimolecular micelles. It is the first demonstration of the self‐assembly mechanism for the large multimolecular micelles generated from the solution self‐assembly of hyperbranched copolymers.