Ring‐Opening Polymerization of ε‐Caprolactone by Poly(ethylene glycol) by an Activated Monomer Mechanism

Summary: The polymerization of ε‐caprolactone (CL) in the presence of HCl · Et₂O by an activated monomer mechanism was performed to synthesize diblock or triblock copolymers composed of poly(ethylene glycol) (PEG) and poly(ε‐caprolactone) (PCL). The obtained PCLs had molecular weights close to the theoretical values calculated from the CL to PEG molar ratios and exibited monomodal GPC curves. We successfully prepared PEG and PCL block copolymers by a metal‐free method.

The non‐metal catalyzed living ring‐opening polymerisation of ε‐caprolactone by PEG.     

Preparation of a Rapidly Forming Poly(ferrocenylsilane)‐Poly(ethylene glycol)‐based Hydrogel by a Thiol‐Michael Addition Click Reaction

The synthesis of a rapidly forming redox responsive poly(ferrocenylsilane)‐poly(ethylene glycol) (PFS‐PEG)‐based hydrogel is described, achieved by a thiol‐Michael addition click reaction. PFS bearing acrylate side groups (PFS‐acryl) was synthesized by side group modification of poly(ferrocenyl(3‐iodopropyl)methylsilane) (PFS‐I) and characterized by ¹H NMR, ¹³C NMR, and FT‐IR spectroscopy. The equilibrium swelling ratio, morphology, rheology, and redox responsive properties of the PFS‐PEG‐based hydrogel are reported.

     

Fabrication of Micropatterned Gold Nanoparticle Arrays as a Template for Surface‐Initiated Polymerization of Stimuli‐Responsive Polymers

Summary: This paper demonstrates a new, reliable, and simple method for fabricating micropatterned nanoparticle arrays that can serve as templates for the surface‐initiated polymerization of polymer brushes. As a proof of concept, we micropatterned gold nanoparticles (Au‐NPs, ≈10 nm) onto glass, silicon, polystyrene, and gold surfaces by a simple three‐step process: (1) microcontact printing of soluble polymer, (2) incubation with a solution of Au‐NPs, and (3) lift‐off of the template in a mixture of ethanol and deionized water. 40 µm wide features were successfully fabricated without any significant defects or nonspecific adsorption on the background. To demonstrate the utility of these Au‐NP templates, we subsequently polymerized N‐isopropylacrylamide by surface‐initiated polymerization, using a surface‐bound initiator.

Synthesis of PNIPAAm brushes from micropatterned Au‐NP.     

Phase Transition Behaviors of Self‐Oscillating Polymer and Nano‐Gel Particles

Summary: Self‐oscillating polymers and nano‐gel particles consisting of N‐isopropylacrylamide and the ruthenium catalyst of the Belousov‐Zhabotinsky reaction have been prepared. In order to clarify the crosslinking effect on the self‐oscillating behavior, the phase transition behaviors were investigated by measuring the transmittance and the fluorescence intensity of the polymer solution and the gel bead suspension. Cooperative effects due to crosslinking will play an important role for the design of nanoactuators.

Chemical structure of poly(NIPAAm‐co‐Ru(bpy)₃).     

Acid‐Degradable Core‐Crosslinked Micelles Prepared from Thermosensitive Glycopolymers Synthesized via RAFT Polymerization

A thermoresponsive block copolymer, namely poly(acryloyl glucosamine)‐block‐poly(N‐isopropylacryamide) (PAGA₁₈₀‐b‐PNIPAAM₃₅₀) was simultaneously self‐assembled and crosslinked in aqueous medium via RAFT polymerization at 60 °C to afford core‐crosslinked micelles exhibiting a glycopolymer corona and a PNIPAAM stimuli‐responsive core. An acid‐labile crosslinking agent, 3,9‐divinyl‐2,4,8,10‐tetraoxaspiro[5.5]undecane, was employed to generate thermosensitive and acid‐degradable core‐shell nanoparticles. Stable against degradation at pH = 6 and 8.2, the resulting core crosslinked micelles readily hydrolyzed into well‐defined free block copolymers at lower pH (30 min and 12 h respectively at pH = 2 and 4).

     

Photo‐Induced Solid‐State Crosslinking of Electrospun Poly(vinyl alcohol) Fibers

Summary: Poly(vinyl alcohol) (PVA) was derivatized by polymer analogous reaction with thienyl acryloyl chloride and processed to submicrometer fibers by electrospinning from aqueous solution. Water solubility of otherwise water‐soluble PVA fibers was reduced considerably by UV crosslinking of thienyl acrylate modified PVA fibers in the solid state. Water stability of these crosslinked fibers was proven by water steam test at 95 °C.

UV/Vis spectrum of PVA‐Thio fibers irradiated for different periods at 300 nm.     

New Poly(propylene glycol)‐ and Poly(ethylene glycol)‐Based Polymer Gelators with L‐Lysine

Summary: New polymer gelators consisting of poly(propylene glycol) or poly(ethylene glycol) and L ‐lysine‐based low‐molecular‐weight gelators have been developed. These polymer gelators were synthesized according to a simple procedure with high reaction yield, and formed organogels in many organic solvents. The organogelation mechanism was proposed from the transmission electron microscopy and FTIR spectroscopy studies.

Structures of the polymer gelators synthesized here.     

Surface‐Functionalized,Ring‐Opening Metathesis Polymerization‐Derived Monoliths for Anion‐Exchange Chromatography

Ring‐opening metathesis polymerization (ROMP) was used for the synthesis of monolithic capillary columns with inner diameters of 200 µm. The resulting polymeric monoliths were characterized by inverse size‐exclusion chromatography (ISEC). Surface functionalization was carried out in situ using 2‐(N,N‐dimethylaminoethyl)norborn‐5‐ene‐2‐ylcarboxylic amide ( 1 ). The resulting functionalized monoliths were successfully used in anion‐exchange chromatography of oligodeoxynucleotides.

     

Electronic Properties and Field‐Effect Transistors of Thiophene‐Based Donor–Acceptor Conjugated Copolymers

Summary: The thiophene‐quinoxaline donor–acceptor conjugated copolymer poly[(thiophene‐2,5‐diyl‐alt‐(2,3‐diheptylquinoxaline‐5,8‐diyl)] (PTHQx) was explored as a semiconductor in thin‐film organic field‐effect transistors (OFETs). A hole mobility of 3.6 × 10⁻³ cm² · V⁻¹ · s⁻¹ and an on/off current ratio of 6 × 10⁵ were observed in p‐channel OFETs made from spin‐coated PTHQx thin films. The electronic structures of PTHQx and a related thiophene‐thienopyrazine donor–acceptor copolymer were calculated by density functional theory. Atomic force microscopy of PTHQx thin films showed a polycrystalline grain morphology that varied with the substrate.

Output (left) and transfer (right) characteristics of a PTHQx (structure shown) organic field‐effect transistor.     

Copolymerization of Hepta‐1,6‐diene with Ethylene Catalyzed by Cobalt Complexes

Copolymerization of hepta‐1,6‐diene with ethylene using a cobalt–bis(imino)pyridine complex affords a polymer that contains trans‐1,2‐five‐membered rings in the repeating unit from hepta‐1,6‐diene. The ratio of the repeating units of diene to those of ethylene is controlled from 3: 97 to 50:50, depending on the reaction conditions. Isotope‐labeling reactions reveal that the major chain transfer pathway involves β‐hydrogen elimination of the polymer end formed after ethylene insertion.

     

Nanosized‐Silica‐Reinforced Holographic Polymer‐Dispersed Liquid Crystals

Summary: Nanosized silicas added to holographic polymer‐dispersed liquid crystals (HPDLC) provide the resin phase with increased elasticity, dimensional stability, and the high diffraction efficiency of the gratings. On the other hand, nucleation and growth of periodic modulation are delayed, especially with small‐sized silica because of the increased viscosity of the resin mixture. Effects of the LC/resin composition and cell gap on the diffraction efficiency have also been studied.

AFM image of silica added HPDLC.     

One‐Pot Synthesis of Well‐Defined Amphiphilic and Adaptative Block Copolymers via Versatile Combination of “Click” Chemistry and ATRP

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

     

Preparation of a Polyethylene Latex by Catalytic Hydrogenation of a Polybuta‐1,4‐diene‐Based Dispersion

Summary: Fully linear polyethylene‐based latexes have been prepared by the hydrogenation of polybuta‐1,4‐diene dispersions. The latter were synthesized via dispersion ring‐opening metathesis polymerization of cycloocta‐1,5‐diene, and hydrogenated using RuCl₂(PPh₃)₃ as catalyst, without any further treatment. A high hydrogenation efficiency was achieved as demonstrated by different techniques including DSC, and ¹H NMR and FT‐IR spectroscopy. The hydrogenation process could be carried out without detrimental effect on particle size and colloidal stability as evidenced by optical microscopy and light scattering analysis.

Optical microscopy photograph of a polybutadiene‐based dispersion after hydrogenation. No change in size is observed.     

1,1‐Diphenyl Ethylene‐Mediated Radical Polymerisation: A General Non‐Metal‐Based Technique For The Synthesis Of Precise Core Cross‐Linked Star Polymers

This communication details the successful synthesis of low polydispersity core cross‐linked star (CCS) polymers via DPE‐mediated polymerisation. We demonstrate the ability to produce poly(methyl methacrylate) and poly(acrylonitrile) CCS polymers that are currently inaccessible via the two most common non‐metal‐based controlled radical polymerisation techniques (NMP and RAFT polymerisations).

     

Preparation of Highly Transparent and Thermally Stable Films of α‐Cyclodextrin/Polymer Inclusion Complexes

Films of an α‐cyclodextrin/poly(ε‐caprolactone) inclusion complex have been successfully prepared and show high transparency and heat resistance in comparison to the pure polymer film. The physical properties, such as transparency, mechanical properties, and thermal stability, of the α‐CD‐PCL‐IC films are found to depend on the α‐cyclodextrin‐to‐polymer stoichiometry.

     

Novel Amphiphilic Degradable Poly(ε‐caprolactone)‐graft‐poly(4‐vinyl pyridine), Poly(ε‐caprolactone)‐graft‐poly(dimethylaminoethyl methacrylate) and Water‐Soluble Derivatives

New amphiphilic graft copolymers that have a poly(ε‐caprolactone) (PCL) biodegradable hydrophobic backbone and poly(4‐vinylpyridine) (P4VP) or poly(2‐(N,N‐dimethylamino)ethyl methacrylate) (PDMAEMA) hydrophilic side chains have been prepared by anionic polymerization of the corresponding 4VP and DMAEMA monomers using a PCL‐based macropolycarbanion as initiator. The water solubility of these amphiphilic copolymers is improved by quaternization, which leads to fully water‐soluble cationic copolymers that give micellar aggregates in deionized water with diameters ranging from 65 to 125 nm. In addition, to improve the hydrophilicity of PCL‐g‐P4VP, grafting of poly(ethylene glycol) (PEG) segments has been carried out to give a water‐soluble double grafted PCL‐g‐(P4VP;PEG) terpolymer.

     

Towards Multipotent Coatings: Chemical Vapor Deposition and Biofunctionalization of Carbonyl‐Substituted Copolymers

Future advances in designing bioactive materials, such as antithrombotic coatings for cardiovascular stents, will require widely applicable and robust methods of surface modification. In this paper, we report on the development of multifunctional polymer coatings made by chemical vapor deposition (CVD) copolymerization. Polymer coatings of various [2.2]paracyclophane derivatives were co‐deposited in controlled ratios and their chemical composition verified by FT‐IR and X‐ray photoelectron spectroscopy. Furthermore, preliminary biocompatibility of these coatings was assessed using human umbilical vein endothelial cells and 3T3 murine fibroblasts. The parallel immobilization of two different antithrombotic biomolecules onto a CVD‐based copolymer is also demonstrated by orthogonal immobilization strategies.

     

Existence of Two Different Isotropic Phases as a Reason for Bistable Phase Behavior of an LC Side‐Chain Polymethacrylate

An isotropic melt of a chiral side‐chain polymethacrylate was studied by electric birefringence technique. A phase transition between two different isotropic phases was detected by Kerr effect and confirmed by WAXS measurements. The obtained experimental data can explain the previously reported bistable phase behavior of the polymer, as conventional Sm A phase is formed in slow cooling whereas a TGB‐like, optically isotropic mesophase in fast cooling.

     

Water‐Soluble Methyl Orange Fibrils as Versatile Templates for the Fabrication of Conducting Polymer Microtubules

One‐dimensional methyl orange fibrils can be easily prepared. They are stable in acidic aqueous solutions and soluble in neutral water. When used to synthesize conducting polymer microtubules, the fibrils act as “hard templates” formally but as “soft templates” effectively. Microtubular structures of polypyrrole, polyaniline, and poly(3,4‐ethylenedioxythiophene) have been achieved successfully via such water‐soluble versatile templates.