Pseudo‐Living Anionic Telomerization of Buta‐1,3‐diene

Low‐molecular‐weight liquid polybutadienes (1 000–2 000 g · mol^?1) consisting of 60 mol‐% poly(buta‐1,2‐diene) repeating units were synthesized via anionic telomerization. Maintaining the initiation and reaction temperature at less than 70 °C minimized chain transfer and enabled the polymerization to occur in a living fashion, which resulted in well‐controlled molecular weights and narrow polydispersity indices. MALDI‐TOF mass spectrometry confirmed that the end groups of liquid polybutadienes synthesized via anionic telomerization contained one benzyl end and one protonated end. In comparison, the end groups of liquid polybutadienes synthesized via living anionic polymerization contained one sec‐butyl or butyl end and one protonated end.

     

Control of the radical polymerization by 2,2,15,15‐tetramethyl‐1‐aza‐4,7,10,13‐tetraoxacyclopentadecan‐1‐oxyl and its sodium salt

The control of the radical polymerization of styrene by 2,2,15,15‐tetramethyl‐1‐aza‐4,7,10,13‐tetraoxacyclopentadecan‐1‐oxyl is reported here in bulk at 90 °C, 120 °C and in miniemulsion. Similarly, the control by its sodium complex is reported in bulk at 90 °C.

M _n vs. conversion for 3 , 3Na , and TEMPO.     

Synthesis of Poly(ethylene terephthalate)‐block‐Poly(tetramethylene oxide) Copolymer by Direct Polyesterification of Reactive Oligomers

The object of this study was the synthesis of thermoplastic elastomer compounds by direct copolyesterification of reactive oligomers of poly(ethylene terephthalate) (PET) and of poly(tetramethylene oxide) (PTMO). PET was glycolysed to synthesise hydroxytelechelic oligomers of PET. Commercially available hydroxytelechelic PTMO was modified to synthesise carboxytelechelic oligomers. The chemical structures of these oligomers were investigated by ¹H NMR and size exclusion chromatography. Multiblock poly(ester‐ether) was then obtained by polyesterification of the hydroxytelechelic and carboxytelechelic oligomers, using different catalysts and different reaction conditions. The best stoichiometric ratio was determined to lead to the highest M _n. The chemical structure of the synthesised poly(ester‐ether) was investigated by size exclusion chromatography and ¹H NMR. The thermal and thermomechanical behaviour of the synthesised poly(ester‐ether) was investigated by differential scanning calorimetry and by dynamic mechanical analysis, and showed a thermoplastic elastomer behaviour. This product could also be an interesting way of chemically recycling PET waste.

Polyesterification of hydroxytelechelic PET with carboxytelechelic PTMO.     

Controlled Synthesis of Well Defined Poly(3‐hydroxyalkanoate)s‐based Amphiphilic Diblock Copolymers Using Click Chemistry

A modular synthesis of short chain length and medium chain length poly(3‐hydroxyalkanoate)s‐b‐poly(ethylene glycol) (PHAs‐b‐PEG) diblock copolymers is described. First, length‐controlled oligomers of hydrophobic poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBHV), poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) (PHBHHx), and poly(3‐hydroxyoctanoate‐co‐hydroxyhexanoate) (PHOHHx) containing a carboxylic acid end group were obtained by thermal treatment, with molar masses ranging from 3 800 to 15 000 g · mol^?1. After quantitative functionalization with propargylamine, ligation with azide‐terminated poly(ethylene glycol) of 5 000 g · mol^?1 was accomplished using the copper (I) catalyzed azide alkyne cycloaddition (CuAAC). Well‐defined diblock copolymers were obtained up to 93% yield, with molar masses ranging from 9 900 to 23 100 g · mol^?1. All products were fully characterized using ¹H NMR, COSY, SEC, TGA, and DSC.

     

p‐Doping and Fiber Spinning of Poly(heptadiyne)s

Poly(4,4‐bis[(3,5‐diethoxybenzoyloxy)methyl]‐1,6‐heptadiyne) is synthesized via cyclopolymerization using modified Grubbs‐ and Schrock‐type initiators. Doping with either I₂ or NO⁺ BF₄^? yields a conductive polymer with conductivity up to 1.4 × 10^?2 S cm^?1. The undoped amorphous conjugated polymer is spun into monofilament and multifilament fibers by a wet‐spinning process. Fibers are collected on bobbins with a draw down ratio of 12 resulting in fiber diameters under 60 μm, characterized by scanning electron microscopy. X‐ray diffraction data confirms that the amorphous structure of the polymer is preserved; no additional orientation of the polymer chains occurs during fiber spinning.

     

Degradation of Poly(butyl acrylate) and Poly(2‐hydroxyethyl methacrylate) Model Compounds Under Extreme Environmental Conditions

The degradation of low‐MW ( = 1 500 g · mol^?1) model compounds of pBA and pHEMA were studied under conditions corresponding to the worst‐case temperatures and irradiation intensities likely to be experienced by a surface coating exposed to the harsh Australian environment. Vinyl‐terminated polymers were compared to their saturated analogues; the terminal vinyl bond was found to be a source of instability which rendered the polymers more susceptible to degradation. The cyclic degradation mechanism derived from degradation of pMMA in our previous publication is also relevant to pBA and pHEMA. In addition, pBA and pHEMA are susceptible to other degradation and crosslinking reactions; crosslinking is particularly rapid in pHEMA exposed to UV radiation.

     

A Study of Copolymerization of 1‐Hexene with 2,5‐Norbornadiene Using Metallocene Catalysts

Summary: Copolymerization of 1‐hexene with a symmetrical diene, namely 2,5‐norbornadiene was studied using four different metallocene catalysts. Copolymerization was found to occur exclusively through one of the two equally reactive endocyclic double bonds with all the four catalysts. Copolymerization results in low molecular weight oligomers with the number average molecular weight ( ) varying from 1 000–3 000. End group analysis of the co‐oligomers revealed that the β‐hydrogen transfer after 2,1 insertion also occurs in the presence of highly regiospecific catalysts. The regio errors were also found to depend on various reaction parameters such as polymerization time, Al/Zr mol ratio, metallocene concentration and polymerization temperature.

Plots of variation in end groups and NBD incorporation with time.     

Protonation of Sulfonated Poly(4,4′‐diphenylether‐1,3,4‐oxadiazole) Membranes

This work describes the effect of sulfuric acid protonation on the properties of SPOD‐DPE membranes using FT‐IR and impedance spectroscopic analyses. The IR spectra showed the protonation of nitrogen atoms from oxadiazole rings, with a broad band complex in the region 3 000–2 100 cm^?1 with two centered peaks at 2 590 and 2 440 cm^?1. The S?O characteristic absorption bands in SPOD‐DPE and sulfuric acid were specially studied in the region of 1 800–900 cm^?1. The band shifts are associated to the interaction between acid groups and oxadiazole ring nitrogen atoms. The IR spectra evidenced the presence of three absorption species (HSO, SO and free H₂SO₄) depending on the sulfuric acid concentration. For the protonated SPOD‐DPE membranes, a proton conductivity around 10 mS · cm^?1 was reached at 50 °C.

     

Kinetics of Shear Microphase Orientation and Reorientation in Lamellar Diblock and Triblock Copolymer Melts as Detected via FT‐Rheology and 2D‐SAXS

The microphase orientation/reorientation alignment kinetics behaviour of lamellar PS‐b‐PB diblock and PS‐b‐PB‐b‐PS triblock copolymers under LAOS conditions is studied. By online monitoring the degree of the mechanical nonlinearity during the orientation process, as determined via the higher harmonics in FT rheology [i.e: I_3/1(t), ?₃(t)], and investigation of the orientation distribution by 2D‐SAXS, the kinetics of the microphase alignment for different experimental shear conditions was followed. For di‐ and triblock copolymers, the shear orientation into parallel alignment is possible and the kinetics of orientation is strongly dependent on the strain amplitude.

     

Benzo[1,2‐b:4,5‐b′]dithiophene‐alt‐terthiophene Copolymers Containing Styryl‐Triphenylamine Side Chains: Synthesis and Photovoltaic Performance Optimization with Fullerene Acceptors

A new two‐dimensional‐conjugated polymer (PBDTT3‐TPA) containing benzodithiophene (BDT) and a side chain isolation comonomer is designed and synthesized. Interestingly, PBDTT3‐TPA is compatible with higher lowest unoccupied molecular level (LUMO) acceptors of indene‐C₆₀ bisadduct (ICBA), and polymer solar cells based on PBDTT3‐TPA/ ICBA show an open‐circuit voltage (V_OC) of ca. 0.80 V and a power conversion efficiency of 2.48% under AM1.5G illumination of at 100 mW cm^?2. Furthermore, the energy loss in the corresponding fullerene acceptor devices is discussed, and the increase in the observed V_OC is explained quantitatively by the up‐shifted LUMO energy of ICBA (0.17 eV) and the reduced saturation current (J_SO) in the blends.

     

Multicyclic Poly(ether ketone)s by Polycondensation of 1,3,5‐Tris(4‐fluorobenzoyl)benzene with Various Diphenols

Summary: 1,3,5‐Tris(4‐fluorobenzoyl)benzene (TFBB) was polycondensed with silylated 4,4′‐dihydroxybiphenyl, bisphenol‐A or 4‐tert‐butylcatechol in N‐methylpyrrolidine with K₂CO₃ as a promoter. The TFBB/diphenol feed ratio was varied from 1.0:1.0 to 1:0:1.5. Partial cross‐linking was observed with the stiff 4,4′‐dihydroxybiphenyl, even at the 1.0:1.0 ratio. With bisphenol‐A, no gelation took place up to a feed ratio of 1.0:1.3, indicating a high cyclization tendency. With 4‐tert‐butylcatechol, no cross‐linking occurred up to the 1.0:1.5 ratio, proving an even higher cyclization tendency. The formation of cyclic, bicyclic and multicyclic oligo‐ and polyethers was detected by means of MALDI‐TOF mass spectrometry for all reaction products. These results demonstrate that increasing chain stiffness reduces the influence of cyclization. Cyclization proved unavoidable, however, and a high cyclization tendency prevents the formation of hyperbranched and networked structures.

     

Polyrotaxanes of Pyrene–Triazole Conjugated Azomethine and α‐Cyclodextrin with High Fluorescence Properties

The paper reports on the preparation of a new 2‐rotaxane monomer through an acid coupling reaction between 1‐pyrenecarboxaldehyde and α‐CD/3,5‐diamino‐1,2,4‐triazole inclusion complex. Pyrenyl groups are large enough to provide a blocking effect toward cyclodextrin de‐threading. The oxidative C? C coupling of 2‐rotaxane in the presence of RuCl₃ catalyst afforded conjugated azomethine polyrotaxanes. The expected modifications of the solubility, morphology, film forming ability for rotaxane polymer were proved. As shown by fluorescence and UV‐vis spectroscopy, a material with optical properties appropriate for use in photonics was obtained.

     

Synthesis of Hydroxyl‐Terminated Poly(vinylcarbazole‐ran‐styrene) Copolymers by Nitroxide‐Mediated Polymerization

A series of poly(vinylcarbazole‐ran‐styrene) copolymers with terminal hydroxyl groups were synthesized using nitroxide mediated polymerization (NMP) with the hydroxyl‐functional initiator VA‐086 and TEMPO as the mediator at 130 °C. Polymerizations were studied as a function of vinylcarbazole feed content, target molecular weight, and VA‐086/TEMPO ratio. The characterization of the copolymers was done by GPC and NMR. For feed concentrations of 40 mol‐% vinylcarbazole, copolymers with vinylcarbazole concentration up to 33 mol‐% could be obtained with narrow molecular weight distributions (PDI = 1.35) and exhibit pseudo‐“living” character up to conversions of about 20% if the target molecular weight was >100 kg · mol^?1. ¹H NMR indicated that the hydroxyl group was retained sufficiently with a functionality typically of about 0.7 hydroxyl groups per chain. Copolymers synthesized with higher vinylcarbazole feed content exhibited slower kinetics and were less controlled, resulting in much broader molecular weight distributions. The absence of control could be attributed to the absence of thermal initiation by vinylcarbazole which is advantageous toward controlling the radical concentration during the polymerization.

     

Synthesis and Characterization of Poly(trimethylene oxide)‐block‐Polystyrene and Poly(trimethylene oxide)‐block‐Polystyrene‐block‐Poly(methyl methacrylate) by Combination of Atom Transfer Radical Polymerization (ATRP) and Cationic Ring‐Opening Polymerization (CROP)

Summary: Diblock copolymers, poly(trimethylene oxide)‐block‐poly(styrene)s abbreviated as poly(TMO)‐block‐poly(St), and triblock copolymers, poly(TMO)‐block‐poly(St)‐block‐poly(MMA)s (MMA = methyl methacrylate), with controlled molecular weight and narrow polydispersity have been successively synthesized by a combination of atom transfer radical polymerization (ATRP) and cationic ring‐opening polymerization using the bifunctional initiator, 2‐hydroxylethyl α‐bromoisobutyrate, without intermediate function transformation. The gel permeation chromatography (GPC) and NMR analyses confirmed the structures of di‐ and triblock copolymers obtained.

GPC curves of (a) poly(St); (b) diblock copolymer, poly(St)‐block‐poly(MMA) before precipitation; (c) poly(St)‐block‐poly(MMA) after precipitation in cyclohexane/ethanol (2:1); (d) triblock copolymer, poly(TMO)‐block‐poly(St)‐block‐poly(MMA).     

Water‐Soluble Conjugated Polyelectrolyte‐Based Fluorescence Enzyme Coupling Protocol for Continuous and Sensitive β‐Galactosidase Detection

A simple, rapid, continuous and homogeneous fluorescent assay for β‐galactosidase was developed, combining an enzyme‐coupled reaction and signal amplification property of conjugated polyelectrolytes (CPs). The procedure is based on a sequence of two coupled biocatalytic steps in which the β‐galactosidase hydrolyzes its substrate to a phenol derivative followed by conversion to quinone (secondary product) with fluorescence quenching ability by the tyrosinase. The fluorescence of PFP?SO is efficiently quenched by the quinone via an electron transfer process. The limit of detection (LOD) of this assay is less than 0.0005 U · mL^?1, which is better than that of electrochemical method and is comparable to that of most sensitive chemiluminescent techniques. In principle, this sensor mechanism will extend the application window of CPs for wide‐spectrum enzyme detections. This “mix‐and‐detect” approach could be expanded to a high‐throughput manner.

     

Photocurable Shape‐Memory Copolymers of ε‐Caprolactone and L‐Lactide

Biodegradable and photocurable block copolymers of ε‐caprolactone and L ‐lactide were synthesized by polycondensation of PLLA diol ( = 10 000 g · mol^?1), PCL diol ( = 10 000 g · mol^?1), and a chain extender bearing a coumarin group. The effect of copolymer composition on the thermal and mechanical properties of the photocured copolymers was studied by means of DSC and cyclic tensile tests. An increase in Young's modulus and a decrease in the tensile strain with increasing PLLA content was observed for the block copolymers. Block copolymers with high PCL content showed good to excellent shape‐memory properties. Random copolymers exhibited R_f and R_r values above 90% at 45 °C for an extremely large tensile strain of 1 000%.

     

Tailor‐Made Soluble Polymer Supports: Synthesis of a Series of ATRP Initiators Containing Labile Wang Linkers

A series of functional initiators for atom transfer radical polymerization (ATRP) was prepared. These structures contain an ATRP initiating site, a labile p‐alkoxybenzyl ester Wang linker and a functional end‐group (i.e., ? COOH, ? N₃, ? OH, ? C?CH, or ? NHFmoc). These novel initiators can be utilized for synthesizing well‐defined soluble polymer supports. For instance, the azide‐, alcohol‐, alkyne‐, and NHFmoc‐ derivatives were tested as initiators for the bulk ATRP of styrene. SEC, MALDI‐TOF‐MS, and NMR measurements indicated that well‐defined polystyrene samples with defined end‐groups have been synthesized in this process. Moreover, it was demonstrated that the labile Wang linkers could be easily cleaved with a mild trifluoroacetic acid treatment.

     

Structure and Phase Transitions of Poly(heptamethylene p,p′‐bibenzoate): Time‐Resolved Synchrotron WAXS and DSC Studies

Time‐resolved wide‐angle X‐ray scattering (WAXS), as well as differential scanning calorimetry (DSC) and polarisation microscopy studies, were applied to investigate the structure and phase transitions of poly(heptamethylene p,p′‐bibenzoate). Temperature dependencies of several structural parameters were determined. Complete transformation from an isotropic melt to a smectic phase was suggested whereas the transition from a smectic to crystalline phase is only partial (around 30%), although it takes place from the ordered SCA phase. Crystals are formed within the SCA domains with nearly the same coherent length. On the basis of the analysis of the position and the profile of the diffuse wide‐angle X‐ray scattering and mesogenic layer spacing, it was assumed that either crystallisation modifies the smectic structure, or mesophase losses its positional order because of the lack of mobility of the spacers at low temperatures.

WAXS scattering profiles corresponding to P7MB: a) cooling from the isotropic melt at 2 °C · min^?1; b) subsequent melting at 12 °C · min^?1.     

Synthesis,Crystallization, and Enzymatic Degradation of the Biodegradable Polyester Poly(ethylene azelate)

Poly(ethylene azelate) (PEAz) was synthesized and its melting behavior was studied with DSC and Step Scan DSC. The equilibrium melting point of PEAz was found 62 °C and the heat of fusion of 100% crystalline polymer was estimated at 160 J · g^?1. Polarized light microscopy showed mixed birefringence. From isothermal crystallization DSC study, after self‐nucleation, crystallization rates were estimated. The Lauritzen–Hoffman plots showed crystallization regime I to II and II to III transition at 34 and 19 °C respectively. Non‐isothermal crystallization was studied. The activation energy was calculated applying the isoconversional method of Friedman. Chemical hydrolysis of PEAz was very slow, while enzymatic hydrolysis showed comparable rates with PCL.

     

Synthesis and Photovoltaic Properties of a Poly(2,7‐carbazole) Derivative Based on Dithienosilole and Benzothiadiazole

A low bandgap poly(2,7‐carbazole) derivative PCDSBT containing dithienosilole and benzothiadiazole is synthesized by Stille polymerization. The incorporation of dithienosilole and carbazole causes PCDSBT to have a broad absorption from 350 to 800 nm and a relatively low HOMO level. Solar cell devices fabricated by blending PCDSBT with [6,6]‐phenyl‐C₆₁‐butyric acid methyl ester (PC₆₁BM) at a 1:2 weight ratio in a mixed solvent of 3% (by volume), 1,8‐diiodooctane, and 97% dichlorobenzene lead to a power conversion efficiency of 1.65% under the illumination of AM 1.5G (100 mW · cm^?2).