Journal of Polymer Science Part A: Polymer Chemistry

A series of amphiphilic triblock copolymers, poly[oligo(ethylene glycol) methacrylate]_x-block-poly(ε-caprolactone)-block-poly[oligo(ethylene glycol) methacrylate]_x were prepared and their self-assembly behavior in water solutions was studied. The interplay of the two hydrophobic and one thermoresponsive macromolecular chains as long with the specific architecture (topology, relative block lengths) and the nature of the blocks of the macromolecule give rise to hierarchically organized micellization. In these rod-coil copolymers, the thermoresponsive rod chains provide a unique self-organization mechanism that yields morphologies, which are nanostructured materials, with structure on the molecular, internal mesophase, and nanoparticle length scales.

Homopolymers bearing terminal azide and alkyne groups can be coupled via click chemistry to yield diblock copolymers. When performed in solvents that dissolved both homopolymers, the click reaction is usually found to be inefficient, probably due to the embedding of the reactive end groups inside the random coils of the polymers. In this paper, we report our discovery that the efficiency of the click chemistry between the terminal azide and alkyne groups of different polymer chains could be drastically increased with the addition of an optimum amount of water into a reaction system. The possible mechanism for this finding is also discussed.

Polyester and poly(ester-co-amide) nanoparticles were synthesized by anionic polymerization in inverse miniemulsion. The composition of the copolymer could be varied in a wide range delivering statistical copolymers. Upon solvent exchange stable aqueous dispersions of the potentially biodegradable copolymers could be obtained.

The copolymers obtained by copolymerization of MMA with fluorinated styrenes were transparent, flexible, and thermally stable. The glass transition temperatures were increased by increasing the content of the fluorinated styrenes because of intrachain interaction between the methyl ester and fluorinated phenyl moieties.

The combination of pyrene with carbazole to construct solution-processable starburst blue light-emitting materials with a peak efficiency of 3.28 cd/A and a maximum brightness of over 2200 cd/m².

The efficiencies of DSSCs fabricated with the liquid-type electrolyte, PMPBMI-gelled, PDBBMI-gelled, PBMI-gelled, and PBMI/0.3 wt % EAMNM-gelled electrolytes under 100 mW cm⁻² illumination are 7.39, 5.83, 5.42, 6.41, and 7.02%, respectively.

PEO-b-PS copolymers prepared by reversible addition fragmentation chain transfer (RAFT) radical polymerization of styrene using poly(ethylene oxide) (PEO)-based trithiocarbonate as a macro-RAFT agent were employed to the synthesis of stable nanoparticles with PEO functionalities on the core surface, where the micellization and cross-linking reactions occur in one pot. The cross-linking was performed using divinylbenzene as a cross-linking agent and AIBN as an initiator to produce the core-shell interface cross-linked micellar nanoparticles.

The free-radical polymerization of the cyclic ketene acetal monomer 2-methylene-1,3,6-trioxocane (MTC) proceeded with 100% ring-opening at all the temperatures studied. Degradable polyester-ethers were synthesized by copolymerization of MTC with 2-methylene-1,3-dioxepane (MDO), designing flexible and hydrophilic polyester-ethers. The reaction characteristics were identified by varying the initiator, the monomer feed, and the temperature.

Polymer electrolyte membrane fuel cells became important because of their usage in clean energy sources. In this study, triazole was immobilized to a stable polymer backbone and high proton-conducting anhydrous polymer membranes were obtained. The proton transport was provided by triazole molecules, which is defined as Grotthuss mechanism. The system reaches a maximum proton conductivity of 0.086 S/cm at 140 °C.

Facile strategy was developed for the fabrication of the monodisperse superparamagnetic pH-sensitive single-layer chitosan hollow microspheres with controllable structure.

A novel method for the preparation of poly(acrylamide) (PAAm) cryogels by photoinitiated polymerization of monomeric precursors was described. A series of PAAm cryogels were easily prepared by irradiating aqueous solutions containing acrylamide and N,N′-methylene(bis)acrylamide as monomer and cross-linker, respectively, in the presence of 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propane-1-one (Irgacure 2959) as water-soluble photoinitiator with the help of freezing–thawing procedures.

Ring-opening polymerization of epoxidized methyl oleate with various ionic-coordinative initiators have been studied. The structure and molecular weight of the resulting polymers have been studied by ¹H- and ¹³C-NMR, MALDI-TOF-MS, and size exclusion chromatography analysis. Polymers with higher molecular weight than those obtained with conventional cationic catalyst are obtained. These materials have been found to consist of a complex mixture of cyclic and linear polymer chains with different chain ends that can be related to the catalyst nature and the occurrence of two main polymerization mechanisms, the cationic and the ionic-coordinative. Transesterification by-side reactions leading to ester linkages in the main chain have been identified. These undesired reactions have been suppressed by copolymerization with small amounts of tetrahydrofuran with no substantial decrease in the polymer yield and molecular weight. Large-scale polymerization of epoxidized methyl oleate is described to further prepare renewable polyether polyols for polyurethane applications.

Segmented and nonsegmented poly(ether urethane) networks were synthesized from polyether polyols obtained by ionic-coordinative polymerization of epoxidized methyl oleate, using 4,4′-methylenebis(phenyl isocyanate) or l-lysine diisocyanate as coupling agents and 1,3-propanediol as the chain extender. These new materials prepared from alternative renewable resources can be valuable substitutes for existing materials in various applications.

H-shaped pentablock ternary copolymers were synthesized via the combination of single-electron-transfer living radical polymerization, atom-transfer radical polymerization, and click chemistry. These copolymers were used to prepare gold nanoparticles with controlled size in aqueous solution without any external reducing reagent. The dependences of thermal responsibility and gold nanoparticle formation on PDMAEMA block length, pH value, and polymer concentration were investigated.

The adhesion of acrylic waterborne pressure sensitive adhesive to low surface energy polymers (e.g., polyolefins and Teflon) was improved by incorporating stearyl acrylate in the PSA backbone. The presence of stearyl acrylate did not affect the polymer microstructure but modified the interaction in the substrate and the elasticity of the adhesive. The combination of these effects resulted in an optimum stearyl acrylate content.

A novel alternating copolymer comprising bis-calix[4]arene-p-phenylene ethynylene and m-phenylene ethynylene units (CALIX-m-PPE) was synthesized using the Sonogashira-Hagihara cross-coupling polymerization. The meta-connectivity brings to the polymer unique luminescent features. An excited-state charge-transfer complex, formed intramolecularly either in fluid or solid state, is proposed to account for the results.

Well-defined block copolymers were successfully prepared by reversible addition fragmentation chain transfer (RAFT) sequential polymerization of the highly reactive functional monomer 2-vinyl-4,4-dimethyl-5-oxazolone with styrene, methyl acrylate, and methyl methacrylate as comonomers using cumyl dithiobenzoate and 2-cyanoisopropyl dithiobenzoate as chain transfer agents. Block copolymerization efficiency was investigated and compared with ab initio calculations.

Well-defined Hexaarmed star-shaped poly(ε-caprolactone)-block-poly(L-lactide) copolymers were synthesized under monomold microwave irradiation. The temperature, accurately measured by IR detection, is maintained constant by power modulation. The crystallization of both the PLLA and PCL blocks within copolymers could be adjusted from the arm length of each block.

Nonideal A₂ + B₃ type hyperbranched polymerization is studied by the reactive bond fluctuation lattice model. The influence of monomer concentration, feed ratio, and reactivity of groups on gel point, molecular weight, and degree of branching are systematically studied. Furthermore, this model is successfully applied to fit the experimental data and provides correspondingly structural information of hyperbranched polymers.

Well-defined linear α-anthracene-ω-maleimide functionalized polystyrene (l-Anth-PS-MI) and linear α-alkyne-ω-maleimide functionalized poly(tert-butyl acrylate) (l-alkyne-PtBA-MI) homopolymers, and linear α-anthracene-ω-maleimide functionalized PS-b-PtBA (l-Anth-PS-b-PtBA-MI) and linear α-anthracene-ω-maleimide functionalized PS-b-poly(ε-caprolactone) (PCL) (l-Anth-PS-b-PCL-MI) block copolymers were obtained via combination of atom transfer radical polymerization (ATRP)/or ring opening polymerization (ROP) and azide-alkyne click reaction strategy. Subsequently, these linear homo and block copolymers were efficiently clicked via Diels-Alder reaction in order to give their corresponding cyclic homo and block copolymers at reflux temperature of toluene for 48 h under 7–4 × 10⁻⁵ M conditions.

Well-defined poly(methyl methacrylate) brushes were synthesized through surface-initiated atom transfer radical polymerization (ATR) on the surface of triethoxy silane based ATR initiator-coated zinc antimonate nanoparticles. Initiator coating on the surface of nanoparticles was done in the presence and absence of diethanolamine. Relatively high-density polymer brush coating observed when the nanoparticles were modified with diethanolamine followed by attachment of initiator on the surface. UV spectroscopy studies revealed that polymer-coated zinc antimonate nanoparticles (b and c) were highly dispersed in organic solvents such as chloroform without sedimentation even after 24 h, when compared with pure nanoparticles (a). These polymer-coated nanoparticles with excellent dispersibility could be useful for UV-resistant coating applications.

Two different triblock copoly(2-oxazoline)s were prepared containing a fluorinated segment as end or middle block. The block copolymers were characterized using MALDI-TOF mass spectrometry, size-exclusion chromatography and NMR spectroscopy.

Activation of the Cu(0) wire was achieved under anaerobic conditions by the reduction of Cu₂O from the wire surface to Cu(0) on treatment with hydrazine hydrate. The SET-LRP of MA catalyzed by activated Cu(0) wire exhibits a dramatic rate acceleration while providing excellent control over molecular weight evolution, molecular weight distribution, and excellent chain-end fidelity.

In this work, synthesis, characterization, photophysical properties, and initiating efficiency of a new photoinitiator, thioxanthone-carbazole (TX-C) possessing both thioxanthone and carbazole chromophoric groups in the structure were reported. Photophysical and polymerization studies revealed that TX-C is an efficient photoinitiator for free radical polymerization acting in the visible light region. Polymerization mechanisms in the presence or absence of an additional coinitiator were proposed.

Two new carbazole-based conjugated polymers, PCDCN and PCDTA, incorporating two strong light-absorbing organic dyes have been synthesized and characterized. The highest power conversion efficiencies of devices based on PCDCN and PCDTA were 2.31% and 2.47%, respectively.

PET/MXD6 melt-mixed blends at 285 °C in presence of the terephthalic acid (1 wt %) give block copolyesteramides at shorter reaction time (15–20 min) and a random copolymer at 120 min heating. The microstructure of all copolyesteramides was investigated by ¹H and ¹³C NMR using CDCl₃/TFA-d/(CF₃CO)₂O mixture as solvent. All PET-MXD6 copolymers show a single T_g that change as a function of their dyads molar composition, whereas the initial biphasic blend present two glass transitions corresponding to that of the polymer components. Measured T_g match with those calculated by an equation that take in account the weight fraction of the copolymer components.

Polysiloxanes containing thermally curable benzoxazine units in the main chain have been synthesized. For this purpose, first the diallyl functional benzoxazine monomer is synthesized. Subsequent hydrosilylation reaction of the resulting allylic monomer (B-ala) with 1,1,3,3-tetramethyldisiloxane (TMDS) in the presence of Pt catalyst yields the corresponding oligo(B-ala-tetramethyldisiloxane)s (OBTMDS). Using the anionic polymerization route, OBTMDS was then converted to poly(bisbenzoxazine dimethylsiloxane)s (PBDMSs) by reacting with readily available cyclic oligomer octamethylcyclotetrasiloxane (D4) or decamethylcyclopentasiloxane (D5) in the presence of tetrabutylammonium hydroxide (TBAH) as catalyst.

It is shown that the MADIX/RAFT ring-closing polymerization of diallyldimethylammonium chloride (DADMAC) in water using a O-ethyl xanthate-type mediating agent is governed by a fast transfer to the MADIX/RAFT agent, ensuring a very good control of molecular weights during polymerization and a relatively slow exchange of the xanthate group between dormant and active species which is responsible for the obtaining of broad molecular weight distributions (M_w/M_n = 1.8–2.0). Reaction conditions were established to prepare well-defined poly(acrylamide)–poly(DADMAC) double hydrophilic neutral–cationic diblock copolymers.

Nonmodified MWCNTs/polyoxadiazole nanocomposites are successfully prepared by a facile solution route. Tensile strength, elongation at break, and tensile energy to break are shown to increase by more than 28, 45, and 73%, respectively. The enhancement of the overall performance of the composites is a result of the fine dispersion and interaction between the polymer and the CNTs.

Three functional bromoxanthate agents (Xanthate₃-Br, Xanthate₂-Br₂, and Xanthate-Br₃) were successfully used to prepare the miktoarm star copolymers PS_n-b-PVAc_4-n via combination of ATRP and RAFT techniques. Both approaches (first ATRP of St and followed by RAFT of VAc and first RAFT of VAc and followed by ATRP of St) controlled each block in PS_n-b-PVAc_4-n by controlling the monomer conversion.

Novel poly(N-9-ethylcarbazole-exo-norbornene-5,6-dicarboximide) and its hybrids were synthesized to apply to hybrid organic light-emitting devices as hole injection and transporting nanolayers (HITLs). These wet-processable hybrid HITLs with good optical and thermal properties as well as strong solvent resistance might be suitable for not only large-area coating through roll-to-roll or ink-jet patterning processes but also for multilayered polymeric light-emitting devices.

The submicron-sized raspberry-like polystyrene/polyacrylonitrile (PS/PAN) particles with anisotropic properties and controllable structure in a high yield were synthesized via γ-radiation-induced seeded emulsion polymerization under ambient pressure and at room temperature, in which the neutralized styrene-divinylbenzene-acrylic acid terpolymer (P(S-DVB-AA)) particles served as both seed particles and stabilizer. The as-prepared PS/PAN particles showed a good monodispersity.

As a universal MADIX agent precursor, isopropylxanthic disulfide (DIP) was used to mediate free radical polymerizations of three “less activated” monomers (LAMs), vinyl acetate (VAc), N-vinylcarbazole (NVC), and N-vinylpyrrolidone (NVP). The polymerizations of these three LAMs (VAc, NVC, and NVP) were successfully well controlled via MADIX polymerization process in the presence of DIP. DIP reacted with AIBN to form xanthate in situ. The successful application of DIP to control LAMs would avoid the complex synthetic procedures of CTAs and is helpful for future large-scale industrial application.

Well-defined nanocapsules have been synthesized via the miniemulsion technique. In one example, a preformed polymer is used to form a shell around the liquid core. In another example, miniemulsion polymerization leads to the shell formation.

Shell-functionalized polymeric nanoparticle was prepared through the method of polymerization-induced self-assembly of block copolymers via one-pot ring-opening metathesis polymerization in a selective solvent. The copolymers and the micelles were characterized by different techniques. The results indicated that the spherical core-shell micelles were stable and reproducible in toluene.

Soft polymeric particles with modifiable core and various shells with different charges were prepared by microemulsion polymerization. The magnetic field–responsive polymeric core–shell particles were prepared by inclusion of magnetic ferrite nanoparticles during the polymerization. The soft polymeric materials and composites have promising potentials in guided active agent delivery as demonstrated in this investigation.

Thermal polymerization of DL-α-lipoic acid (LPA) in bulk without any initiators gave polymer above the melting point. The molecular weight determined by GPC was estimated to be high. Poly(LPA) was found to be a cyclic structure from the analysis of ¹H NMR and ESI-MS spectra of the resulting polymer. The interlocked polymer consisted of poly(LPA) and dibenzo-30-crown-10 spatially entangled with each other was synthesized by the polymerization of LPA in the presence of cyclic dibenzo-30-crown-10.

cis-Alkenes can be quantitatively converted to the trans isomers within 1.5 h under sonication in chloroform at 0 °C. The isomerization follows the first-order kinetics. Via using poly(phenylenevinylene) derivatives, the sonication-induced isomerization is demonstrated to be a potentially useful tool in the preparative organic and polymer chemistry.

PEG/CD polyrotaxane was prepared under seven conditions with different temperature and presence/absence of different types of end-capping molecules (adamantanamine or diphenylethylamine). The polyrotaxane was synthesized even without the addition of end-capping molecules, via undesirable esterification between terminal carboxyls of PEG and hydroxyls in CDs. Decomposition behavior of the obtained polyrotaxanes were characterized by means of gel permeation chromatography (GPC), ¹H NMR and alkaline hydrolysis examination. The GPC results suggested that the ester-capped polyrotaxanes were found to be decomposed over months at room temperature and humidity.

For the heterogeneous oxidative polymerization of thiophene starting homogeneously in organic solvents (e.g., ethanol) using small molecule surfactants such as sodium dodecyl sulfate (SDS) generally fails to form stable dispersed phase because completely dissolved SDS cannot form micelles therein. But, if an appropriate macromolecular stabilizer with sufficient excluded volume such as polyvinylpyrrolidone is used, well dispersed polythiophene microspheres can be obtained through the steric stabilization mechanism.