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Various failure modes derived from the electrochemical migration (ECM) through the dielectric polymer layers have been considered critical issues in the electronic devices. Herein, we for the first time suggested the rationally designed epoxy/zeolitic imidazolate framework-8 (ZIF-8) nanocomposite materials for efficient suppression of copper ion migration based on the plausible reaction mechanisms of metal metathesis addressed by sequential cleaving and ligating between metal ions (Zn2+ and Cu2+) and 2-methylimidazole (2-mim) ligands. The fabrication process for epoxy/ZIF-8 (EZ) nanocomposites was first examined to optimize the crosslinking system. The capability of the metal ion capture in the EZ nanocomposites was examined using the aqueous solution containing Cu2+ ions. In addition, the ECM suppression properties were evaluated using the thermal humidity bias (THB) model testing. The representative model investigations with the EZ nanocomposites exhibited substantially enhanced copper ion adsorption and suppression of copper migration in comparison to those of epoxy. Hence, the EZ nanocomposites can be one promising material to alleviate the undesired ECM behavior in electronic device applications.

Herein, environmentally benign chitin nanofiber (ChNF) membranes were fabricated by regulating suspension behavior. The introduction of zeolitic imidazole frameworks (ZIF-8) into the composite membranes led to the domain formation of ChNF derived by coordinative interaction, resulting in pore size-tunable membranes. Based on the rheological, morphological, and structural characterizations, the driving force of pore-size control was studied in the aqueous suspension of ChNF and ZIF-8 according to the relative concentration. At critical concentration, the 30-ChNF membrane presents superior water permeance (40 LMH h−1) while maintaining a high rejection rate (>80% for all organic dyes). Moreover, the molecular size cut-off of the composite membranes for dyes can be controlled in the range of less than 1 nm to 2 nm. The experimental results provide a simple strategy for the preparation of pore tunable ChNF membranes using MOF with high mechanical strength, good durability, high flux, dye rejection, and antifouling ability.

A series of multi-crosslinkable, self-healing, ladder-structured polysilsesquioxane inorganic-organic hybrid materials were developed to enhance the mechanical properties through tandem UV-curing and Diels-Alder chemistry. The introduction of UV-curable acryl- or epoxy groups allowed for a higher degree of crosslink density while bringing the inorganic backbones closer together for highly efficient self-healing properties, all with a singular material as the ternary organic functional groups consisting of UV-curable function, diene, and dienophile were tethered to the well-defined inorganic backbone. Exceptional thermal stability (>400 °C), optical transparency (>95%), solution processability, as well as robust surface mechanical properties in both bulk (pencil hardness 6H) and nanoscale (elastic modulus > 9 GPa), properties which can be adroitly recovered through mild and rapid thermal treatment hold great promise for next generation hybrid smart coating materials for application in optoelectronic devices.

Heteroleptic ruthenium-complexed ladder-like structured polysilsesquioxane (LPSQ-Ru) was synthesized by post coordination reaction of bidentate ligand side chains in LPSQ with reactive Ru(II) complexes, which was well characterized by 1H and 29Si NMR, FT-IR, and spectroscopic techniques. The photophysical properties of LPSQ-Ru were examined by UV and PL analyses in both solution and solid states, comparing to analogous polymers of ruthenium-complexed polystyrene (PS-Ru). Obtained absorptions of LPSQ-Ru and PS-Ru were broadened ranging from 390-490 nm regardless of the states. However, LPSQ-Ru exhibited higher and shaper PL emission spectrum in comparison to that of PS-Ru, particularly in the solid state, because Ru-complexes in LPSQ were much effectively isolated, preventing their aggregations due to the rigid double strained siloxane backbone. This extinguished photophysical property in LPSQ-Ru kept after intensive thermal treatment at 250 °C for 90 min, which was not achieved in PS-Ru (~5-fold decrease). These differences originated from the backbone structures were also appeared in electrochemical properties in the solid states.

An in-depth examination of the self-healing properties of both dienophile and diene functionalized ladder-like structured polysilsesquioxane copolymers and terpolymers was investigated. Through functionalization of both diene and dienophile on the double-stranded siloxane backbone with ternary n-alkyl functional groups acting as chain mobility control, the effect of chain mobility and chemical structure on self-healing and mechanical properties were elucidated. All of the single component self-healing hybrid materials exhibited fast healing times (∼5 min), and their de-crosslinked adducts exhibited exceptional retention of solubility in common organic solvents for good reusability, all while having inherent high thermal stability and optical transparency.

The incorporation of pyrene-functionalized poly(methyl methacrylate)-b-poly(dimethylaminoethyl methacrylate) (PMMA-b-PDMAEMA) ionic block copolymer-wrapped carbon nanotubes (PBCNTs) with graphene oxide (GO) allows compact decoration of metal nanoparticles (NP) for use as robust catalysts. This well-tailored concept of the PBCNT-GO functional carbon support provides various features, including a two-dimensional (2D) structure, dimensional stability, versatile solubility (from toluene to water), enhanced diffusion of reagents, and recyclability. Among the various compositions of GO and PBCNT, 50 wt% of the PBCNT additive-containing support (PBCGO55) showed great hybridization potential for Ag, Au, and Pd NPs. In particular, the hybridization of PBCGO55 with Pd NPs (Pd-PBCGO55) displayed superior morphological features with compact decoration of ultra-fine NPs (1–3 nm), larger surface area, higher density of edge and corner atoms, better dispersion stability, and lesser aggregation of the decorated Pd NPs in comparison with the other hybrid catalysts. In the catalytic reduction of 4-nitrophenol (4-NP), the Pd-PBCGO55 hybrid catalyst exhibited the best catalytic performance, resulting in highly enhanced reaction rate constant (k) of 9.73 min−1 and catalytic activity of 141.8 mol mol−1 min−1, exhibiting a 50-fold increased rate constant and 30-fold increased catalytic activity in comparison to Ag-GO without PBCNT (k = 0.19 min−1, catalytic activity = 4.58 mol mol−1 min−1).

A series of well-defined hard–soft–hard triblock copolymers were synthesized by Ru-based atom transfer radical polymerization (ATRP) (MWD < 1.26) in order to examine their electromechanical properties under electric fields. The obtained methacrylate based triblock copolymers consisted of poly(dodecyl methacrylate) (PDMA) soft middle block segments and three different hard block segments with poly(methyl methacrylate) (PMMA), poly(tert-butyl methacrylate) (PtBMA), and their random copolymers (PMTDTMTs). Polar acidified triblock copolymers were also prepared by deprotecting tert-butyl groups in tBMA-incorporating hard block segments through simple thermal treatment at 200 °C for 120 min, which in situ gave poly(methacrylic acid) (PMAA) and its random copolymers (PAMDMA) in the hard block segments. SAXS and AFM studies indicated that these triblock copolymers showed well-organized phase separations with different domain sizes, which were strongly dependent on the amount of bulky PtBMA or polar PMAA in the hard block segments. In addition, these triblock copolymers had a variety of morphologies affecting their mechanical (elastic modulus) and electrical (dielectric constant) properties, leading to a tuning of their electromechanical properties. The transverse strains of these triblock random copolymers as a function of an applied electric field indicated that the PTMDMT series possessed the best electromechanical properties, exhibiting an 11-fold enhancement relative to the corresponding acidified polymer PAMDMA at 50 Vpp μm−1 due to a dramatic decrease of the elastic modulus from 4.04 to 0.05 MPa in spite of an increase of the dielectric constant from 3.6 to 5.1. In situ SAXS analysis under an electric field showed that these bulk strains originated from nano-structured microdomain changes.

Poly(vinylidenefluoride-co-trifluoroethylene) (PVDF-TrFE)/SWCNT nanocomposites with ultra-low percolation threshold were prepared by interfacial control using a block copolymer comapatibilizer. For this, a well-defined block copolymer of poly(3-hexylthiophene) (P3HT) and poly(methyl methacrylate) (PMMA) (P3HT-b-PMMA) was synthesized by combination of GRIM and ATRP (Mn = 24 K, Mw/Mn = 1.25), where the P3HT block segment wrapped the SWCNTs by π–π interaction and the resulting PMMA block segment dangled from the SWCNTs, which gave de-bundled SWCNTs without any aggregations for over 5 months in most common organic solvents for PMMA. The block copolymer coated SWCNT (TMCNT) was then mixed with PVDF-TrFE to prepare PVDF-TrFE/SWCNT nanocomposites (PVT-TMCNT), which enabled excellent dispersion of SWCNT in a PVDF-TrFE matrix without aggregation due to the miscibility of the PMMA on TMCNT and PVDF-TrFE. Obtained PVT-TMCNT showed large enhancements of the electrical conductivity and the dielectric constant with ultra-low percolation threshold (fc = 0.07 wt.%) due to excellent interfacial control by the block copolymer comapatibilizer between SWCNT and PVDF-TrFE. Improved ferroelectric properties of PVT-TMCNT were also observed by an increase of field-induced polarization response, which was almost over 10-times higher than for neat PVDF-TrFE.

Compatible hybrid composites (PVLPMA) comprising of poly(vinylidene fluoride) (PVDF) and UV-curable ladder-like polysilsesquioxane (LPMASQ) were investigated for maximizing synergetic effects in various properties. The PVDF fluoropolymer was found to be well-incorporated with the LPMASQ inorganic filler because of good hydrogen-bonding, and the compatibility rigorously investigated by FT-IR, DSC, and WAXS studies. In addition, the crosslinkable function arising from the methacryl-group of the LPMASQ inorganic filler with the aid of the radical source was evaluated from the analysis of various properties. After UV-crosslinking, PVLPMA hybrid composites showcased enhanced mechanical properties such as elastic modulus, surface modulus, and surface hardness with accordance to the increasing the LPMASQ quantity. In addition, hydrophobicity was observed through the increase in the water contact angle up to 115°, a value much larger than that of neat PVDF and cured LPMASQ. Furthermore, the enhanced electrical stability of PVLPMA hybrid composites was obtained through examination of dielectric properties and breakdown strength in comparison to neat PVDF. These PVDF-LPMASQ organic-inorganic compatible hybrid composites with enhanced properties arising from the good compatibility and synergetic effects can be applicable in the various fields supplanting neat PVDF.

Through fine-tuning of the myriad of reaction conditions for an aqueous base-catalyzed hydrolysis–polycondensation reaction, a facile synthesis of structurally controlled polyphenylsilsesquioxanes was developed. Mechanism and kinetic studies indicated that the condensation reaction proceeded through a T1 structured dimer, which was quantitatively and in situ formed through mild hydrolysis of a phenyltrimethoxysilane (PTMS) monomer, to give either the cage-structured polyhedral oligomeric silsesquioxanes (POSS) or the corresponding ladderlike silsesquioxane (LPSQ) with excellent yields. Ladderlike and POSS materials were selectively achieved at higher and lower initial concentrations of PTMS, respectively, and an in-depth spectroscopic analysis of both compounds clearly revealed their structural differences with different molecular weights.

A series of thiol-ene UV-curable inorganic–organic hybrid polysilsesquioxanes of various phenyl:methacryloxypropyl and phenyl:mercaptopropyl copolymer compositions were synthesized in one-batch using a base-catalyzed system. These thermoplastic photocurable ladder-like structured materials were examined as scratch-resistant, hard-coating materials on both glass and PET substrates. The unique fully condensed structure of the hybrid polymers allowed for simplified processing and through variation of the organic functional group, films with high transparency, tunable refractive indices in the range of 1.467–1.546, pencil hardness values of 9H, and high nanoindentation modulus were obtained (7 GPa). These scratch-resistant polysilsesquioxanes may provide insight into the different organic functional group compositions which allow for optimal mechanical properties.

A ladder-like structured poly(mercaptopropyl)silsesquioxane (LPMPSQ) was synthesized in one-bath, under mildly basic conditions at room temperature. Obtained LPMPSQ was utilized as a macroinitiator for thiol-ene graft photopolymerization of various vinyl monomers to give hard, soft, hydrophobic, and hydrophilic graft copolymers with low PDI (

A series of azido-functionalized ladder-like structures was prepared by direct azidation of ladder-like structured poly(p-chloromethylphenyl)silsesquioxane (LPCMPSQ) and poly(chloropropyl)silsesquioxane (LPAPSQ) in excellent yields with perfect substitution of the chloro-compounds. The azido-functionalized silsesquioxanes obtained were then photocured without additional photoinitiator to give highly cross-linked thin films with an exceptionally high modulus (> 12 GPa). Furthermore, these materials were shown to be patterned through photolithography to give impeccable micropatterned microstructures.

A series of ABA triblock copolymers of methyl methacrylate (MMA) and dodecyl methacrylate (DMA) [poly(MMA-b-DMA-b-MMA)] (PMDM) were synthesized by Ru-based sequential living radical polymerization. For this, DMA was first polymerized from a difunctional initiator, ethane-1,2-diyl bis(2-chloro-2-phenylacetate) with combination of RuCl2(PPh3)3 catalyst and nBu3N additive in toluene at 80 °C. As the conversion of DMA reached over about 90%, MMA was directly added into the reaction solution to give PMDM with controlled molecular weight (Mw/Mn ≤ 1.2). These triblock copolymers showed well-organized morphologies such as body centered cubic, hexagonal cylinder, and lamella structures both in bulk and in thin film by self-assembly phenomenon with different poly(methyl methacrylate) (PMMA) weight fractions. Obtained PMDMs with 20–40 wt % of the PMMA segments showed excellent electroactive actuation behaviors at relatively low voltages, which was much superior compared to conventional styrene-ethylene-butylene-styrene triblock copolymer systems due to its higher polarity derived from the methacrylate backbone and lower modulus. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013

A series of high molecular weight polymethylsilsesquioxanes (PMSQs) were synthesized through polymerization of an isolated hydroxyl-substituted cyclic siloxane stereoisomer, cis-trans-cis 1,3,5,7 tetramethyl 1,3,5,7 tetrahydroxyl cyclosiloxane, for interlayer dielectric (ILD) application as low dielectric materials. The molecular weights of PMSQs were controlled by varying polycondensation time. Structural analyses of the obtained PMSQs were carried out by gel chromatography (GPC), FTIR, 29Si NMR, static light scattering (SLS), solution X-ray scattering, and X-ray diffraction. The change in molecular shape of the PMSQs went from linear to branched in structure as molecular weight increased. Furthermore, thin film properties were investigated for application as interlayer dielectric materials. As structural branching increased, its properties showed isotropic tendencies, relatively high modulus (5.4 GPa), and low dielectric constant (2.74) with increase in the inter-molecular space.

The stereo cyclic siloxane compounds having tetra hydroxyl and tetra methyl group were synthesized by hydrolysis of tetrahydrido tetramethyl cyclosiloxane consisting of four stereoisomers. Among the stereo cyclic isomers, cis-trans-cis tetrahydroxyl tetramethyl cyclosiloxane (2) was separated by recrystallization and was used as a monomer species for preparation of ladder-like polymethylsilsesquioxane (PMSQ). The isolated isomer was directly polymerized in THF with potassium carbonate (K2CO3) by systematic ring condensation. The hydrolyzed stereoisomers were characterized by 1H and 29Si NMR, and HPLC. The structure of the synthesized PMSQs were characterized by size exclusion chromatography (SEC), MALDI-TOF mass, 29Si NMR, and small angle X-ray scattering (SAXS).

Various ladder-like structured poly(phenyl-co-methacryl silsesquioxane)s (LPMSQ)s with high molecular weight (Mw = 10,000 ∼ 40,000) were synthesized by direct hydrolysis and polymerization in the presence of base catalyst at 25 °C. Synthesized LPMSQs mainly showed ladder-like structure and photo-cure reaction by 100 mW/cm2 (360 nm) for 10 s without any photo-cure initiators. Chemical composition and structural analysis of the obtained LPMSQs were characterized using 1H NMR, 29Si NMR, Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), and X-ray diffraction (XRD). Physical properties of LPMSQs before and after photcuring were analyzed by Nanoindentation. Surface modulus increased to 8GPa and hardness of thin films increased from 100 to 400 MPa. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

Regioregular poly(3-hexyl thiophene) (rr-P3HT)-based star polymers were synthesized by a crosslinking reaction of the linear rr-P3HT macroinitiator and ethylene glycol dimethacrylate (EGDMA) crosslinker through Ru-based atom transfer radical polymerization (ATRP), where the rr-P3HT macroinitiator was prepared by Grignard metathesis method (GRIM) followed by end functionalization of the ATRP initiator with chlorophenylacetate (CPA) to the rr-P3HT. Relatively high molecular weight of the star polymers were obtained (Mp = 8,988,000 g/mol), which consisted of large numbers of the rr-P3HT arm chains radiating from the EGDMA-based microgel core. The yield of the star polymers were strongly affected by the added amount of the EGDMA crosslinker. The crystalline structure of the rr-P3HT by intermolecular π-π stacking interaction gradually decreased as the star polymer formed, which was confirmed by differential scanning calorimeter (DSC), atomic force microscopy (AFM), and electro-optical analyses. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

Well-defined photo and pH-sensitive amphiphilic star block copolymers were synthesized by copper based atom transfer radical polymerization, which consisted of a hydrophilic pH sensitive shell and photosensitive hydrophobic core structure. For this, photosensitive n-butyl acrylate (nBA) star polymer was synthesized with a multi-functionalized initiator including Pd-coordinated porphyrin in combination with CuBr and 4,4′-dinonyl-2,2′-bipyridyl (dNbpy) (PDI < 1.09). This hydrophobic photosensitive nBA star polymer was then used as a macroinitiator and polymerized with N,N′-dimethylamino ethyl methacrylate (DMAEMA) in the CuCl/CuCl2/dNbpy catalytic system to synthesize PnBA-PDMAEMA star block copolymer, where the PDMAEMA block segment worked as a base exterior. For the arm chain consisted of an acid exterior block segment, the nBA star polymer macroinitiator was polymerized with tert-butyl acrylate (tBA) in the CuBr/dNbpy catalytic system to synthesize the PnBA-PtBA star block copolymer followed by a treatment with strong acid for deprotecting the tert-butyl groups in the PtBA block segment to give PnBA-poly(acrylic acid) (PAA) star block copolymer. Both amphiphilic photosensitive star block copolymers showed well defined molecular weights with narrow polydispersities (PDI < 1.23). Open image in new window

Poly(propyl carbazole silsesquioxane) (PPCSQ) with a high molecular weight (M w = 10,200) was synthesized by the direct hydrolysis of 9-[3-(trimethoxysilyl) propyl]-9H-carbazole with K2CO3, followed by a condensation reaction in an H2O/dimethylformamide (DMF) mixture solvent at 25 °C. The obtained PPCSQ consisted of ladder-like structured siloxane bonds with carbarzole groups as the pendant group, where the distance between two carbarzole pendant groups through the siloxane backbone was 15.6 A and the mean thickness of the siloxane backbone was 4.3 A. This PPCSQ was thermally stable up to 450 °C and the glass transition temperature was ca. 95 °C, showing good film formablity by spin casting.

In this study, new polymeric adsorbents, 2 types of polystyrene-block-poly (N-isopropylacrylamide) (PSN, structure of hydrophobic core and hydrophilic shell), were developed and applied for removal of organic pollutants from wastewater. Encapsulation of organic pollutants by the polystyrene-block-poly (N-isopropylacrylamide) (PSN) resulted in increasing hydrophobicity of the polystyrene with abundant hydrophobic spaces within the amphiphilic block copolymer. The encapsulation mechanism of BTEX by PSN was investigated and found to be mainly attributable to the Van der Waals interactions between the aromatic ring of BTEX and the hydrophobic core of PSN. Polystyrene-block-poly (N-isopropylacrylamide) showed good potential as a novel and cost effective adsorbent for application to wastewater treatment, which can be simply regenerated and reused using an external temperature changing system.

Well-defined sulfonated polystyrene and block copolymers with n-butyl acrylate (nBA) were synthesized by CuBr catalyzed living radical polymerization. Neopentyl p-styrene sulfonate (NSS) was polymerized with ethyl-2-bromopropionate initiator and CuBr catalyst with N,N,N',N'-pentamethylethyleneamine to give poly(NSS) (PNSS) with a narrow molecular weight distribution (MWD < 1.12). PNSS was then acidified by thermolysis resulting in a polystyrene backbone with 100% sulfonic acid groups. Random copolymers of NSS and styrene with various composition ratios were also synthesized by copolymerization of NSS and styrene with different feed ratios (MWD < 1.11). Well defined block copolymers with nBA were synthesized by sequential polymerization of NSS from a poly(n-butyl acrylate) (PnBA) precursor using CuBr catalyzed living radical polymerization (MWD < 1.29).

Diblock star polymers were synthesized via atom transfer radical polymerization from a palladium porphyrin macroinitiator. The arms of the star polymers had an amphiphilic design, with the central Pd-porphyrin surrounded by a relatively hydrophobic block of poly(butyl acrylate) and terminated by a hydrophilic block of poly(oligoethyleneglycol monomethylether monomethacrylate). The size of both the interior and exterior blocks of the polymer arms were tuned over a wide range of molecular weights with the exterior block used to solubilize the stars in polar media. The star polymers showed enhanced reactivity in the oxidation of 2-furaldehyde relative to a small molecule porphyrin, suggesting that the polymer backbone aids with catalytic turnover. Oxygen diffusion studies indicate that the polymer backbone shields the porphyrin excited state from oxygen quenching. Shielding is independent of molecular weight and polymer composition, but it is not pronounced enough to retard the rate of singlet oxygen generation under preparative photooxidation conditions.

Star poly(methyl methacrylate)s (P*) of various arm lengths and core sizes were synthesized in high yields by the polymer linking reaction in Ru(II)-catalyzed living radical polymerization. The yields of the star polymers were strongly dependent on the reaction conditions and increased under the following conditions: (1) at a higher overall concentration of arm chains ([P*]), (2) with a larger degree of polymerization (DP) of the arm chains (arm length), and (3) with a larger ratio (r) of linking agents to P* (core size). In particular, the yields sharply increased in a short time at a higher temperature, in a polar solution, and at a higher complex concentration after the addition of linking agents. These star polymers were then analyzed by multi-angle laser light scattering to determine the weight-average molecular weight (3.8 × 103 to 1.5 × 106), the number of arm chains per molecule (f = 4–63), and the radius of gyration (Rz = 2–22 nm), which also depended on the reaction conditions (e.g., f and Rz increased as [P*], DP, and r increased). Small-angle X-ray scattering analyses of the star polymers showed that they consisted of spheres for which the radius of the microgel core was 2.7 nm. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2245–2255, 2002

Star polymers with end-functionalized arm chains (surface-functionalized star polymers) were synthesized by the in situ linking reaction between ethylene glycol dimethacrylate (linking agent) and an α-end-functionalized linear living poly(methyl methacrylate) in RuCl2(PPh3)3-catalyzed living radical polymerization; the terminal on the surface functionalities included amides, alcohols, amines, and esters. The star polymers were obtained in high yields (75–90%) with initiating systems consisting of a functionalized 2-chloro-2-phenylacetate or -acetamide [FC(O)CHPhCl; F = nPrNH, HOCH2CH2O, Me2NCH2CH2O, or EtO; initiator] and n-Bu3N (additive). The yield was lower with a functionalized 2-bromoisobutyrate [Me2NCH2CH2OC(O)CMe2Br] initiator or with Al(Oi-Pr)3 as an additive. Multi-angle laser light scattering analysis showed that the star polymers had arm numbers of 10–100, radii of gyration of 6–23 nm, and weight-average molecular weights of 1.3 × 105 to 3.0 × 106, which could be controlled by the molar ratio of the linking agent to the linear living polymers. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1972–1982, 2002

Various star-shaped copolymers of methyl methacrylate (MMA) and n-butyl methacrylate (nBMA) were synthesized in one pot with RuCl 2 (PPh 3 ) 3 .-catalyzed living radical polymerization and subsequent polymer linking reactions with divinyl compounds. Sequential living radical polymerization of nBMA and MMA in that order and vice versa, followed by linking reactions of the living block copolymers with appropriate divinyl compounds, afforded star block copolymers consisting of AB- or BA-type block copolymer arms with controlled lengths and comonomer compositions in high yields (≥90%). The lengths and compositions of each unit varied with the amount of each monomer feed. Star copolymers with random copolymer arms were prepared by the living radical random copolymerization of MMA and nBMA followed by linking reactions.

A series of functionalized 2-bromoisobutyrates and 2-chloro-2-phenylacetates led to α-end-functionalized poly(methyl methacrylate)s in Ru(II)-catalyzed living radical polymerization; the terminal functions included amine, hydroxyl, and amide. These initiators were effective in the presence of additives such as Al(Oi-Pr)3 and n-Bu3N. The chlorophenylacetate initiators especially coupled with the amine additive gave polymers with well-controlled molecular weights (Mw/Mn = 1.2–1.3) and high end functionality (Fn ∼ 1.0). © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1937–1944, 2002

Core-functionalized star-shaped polymers consisting of linear poly(methyl methacrylate) arms and a microgel core with functional groups were found to act as efficient hosts for selective interaction with small organic molecules as guests. For example, star polymer 1 with an amide-functionalized core (Mw = 1.21 × 103; DP(arm) = 100; 71 arms/molecule; −NH−CO− in the core) could interact with benzoic acid, benzyl alcohol, and benzylamine, whereas such interaction was absent with acetophenone, ethyl benzoate, and amylbenzene, indicating that the interaction stems from hydrogen bonding between the host's amide core and the guest. Thus, polymer 1 specifically interacts with benzoic acid in an equimolar mixture of the acid and its ethyl ester. The host−guest interaction is inhibited by polar solvents such as DMF and by acids like CF3CO2H.

A hydrophilic ruthenium complex with ionic phosphine ligands {1: RuCl2[P(3-C6H4SO3Na)(C6H5)2]2} induced controlled radical polymerization of 2-hydroxyethyl methacrylate (HEMA) in methanol under homogeneous conditions; the initiator was a chloride (R-Cl) such as CHCl2COPh. The number-average molecular weights of poly(HEMA) increased in direct proportion to monomer conversion, and the molecular weight distributions were relatively narrow (Mw/Mn = 1.4–1.7). A similar living radical polymerization was possible with (MMA)2-Cl [(CH3)2C(CO2CH3)CH2C(CH3)(CO2CH3)Cl] as an initiator coupled with amine additives such as n-Bu3N. In a similar homogeneous system in methanol, methyl methacrylate (MMA) could also be polymerized in living fashion with the R-Cl/1 initiating system. Especially for such hydrophobic polymers, the water-soluble ruthenium catalyst was readily removed from the polymers by simple washing with an aqueous dilute acid. This system can be applied to the direct synthesis of amphiphilic random and block copolymers of HEMA and MMA. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2055–2065, 2002

A half-metallocene iron iodide complex [Fe(Cp)I(CO)2] induced living radical polymerization of methyl acrylate (MA) in conjunction with an iodide initiator [(CH3)2C(CO2Et)I, 1] and Al(Oi-Pr)3 to give polymers of controlled molecular weights and narrow molecular weight distributions (MWDs) (Mw/Mn < 1.2). With the use of chloride and bromide initiators, the MWDs were broader, whereas the molecular weights were similarly controlled. Other acrylates such as n-butyl acrylate (nBA) and tert-butyl acrylate (tBA) can be polymerized with 1/Fe(Cp)I(CO)2 in the presence of Ti(Oi-Pr)4 and Al(Oi-Pr)3, respectively, to give living polymers. The 1/Fe(Cp)I(CO)2 initiating system is applicable for the synthesis of block and random copolymers of acrylates (MA, nBA, and tBA) and styrene of controlled molecular weights and narrow MWDs (Mw/Mn = 1.2–1.3). © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2033–2043, 2002

A series of microgel core-functionalized star-shaped polymers were synthesized by the polymer linking reaction method in RuCl2(PPh3)3-catalyzed living radical polymerization. The synthesis was achieved by the polymer linking reaction method; i.e., functionalized divinyl compounds were added in situ to the solution of linear living poly(MMA)s prepared with the Ru(II)-catalyzed living radical polymerization. The functionalized microgel cores thus obtained contained acrylamide and methacrylamide. Also, star polymers with varying densities of the microgel cores were prepared from diacrylamides with various lengths and structures of the spacer, and by changing the relative amounts of MMA (arm length) and divinyl compound (core size) to initiator, a variety of core-functionalized star polymers could be obtained in high yield, These core-functionalized star-shaped polymers have f of 20−640, Mw of 3.3 × 105−1.3 × 107, and Rz of 5−42 nm. These results indicated that the cores carry as many as 440−51 000 amide grou...

Star-shaped polymers that consist of well-defined poly(methyl methacrylate) [poly(MMA)] arms and a microgel core of a divinyl compound were prepared in high yield with the RuCl2(PPh3)3-catalyzed living radical polymerization followed by direct in-situ polymer linking reactions with divinyl compounds. In typical examples, these star-shaped polymers had the arm number (f) of 10−30 and Mw(star) > 105. The following factors were effective in the star-shaped polymer formation: (a) a monofunctionalized chloride initiator; (b) a linking agent with a soft aliphatic or a rigid long aromatic spacer between the two methacryloyl groups.

Cage dodecaphenylsilsesquioxane (T12-Phenyl) was synthesized in a one batch, mildly basic aqueous solution under room temperature conditions using a trialkoxysilane precursor. Significant improvements in synthetic yield (95%) were observed compared with previous reports. Kinetic studies of the hydrolysis of phenyltrimethoxysilane were conducted and the condensation was monitored by (29)Si NMR which revealed the presence of a transient, intermediary T1 species as the pathway to dodecaphenylsilsesquioxane spherulites, and the tendency for T12 structures over T8, T10, and other substructures was explained through MM2 simulations.

A well-defined PNIPAM-PS star block copolymer with a porphyrin core was synthesized by a reversible addition–fragmentation chain-transfer (RAFT) process, and was found to efficiently capture and decompose environmentally toxic organic materials such as benzene, toluene, ethylbenzene, and xylene (BTEX) in water under UV irradiation and was easily recycled by filtration after simple thermal treatment.

Photo and temperature cured polymer dielectrics could be fabricated on a gate-patterned glass, with two immiscible polymer precursors, divinyltetramethyldisiloxane-bis(benzocyclobutene) (BCB precursor) and poly(melamine-co-formaldehyde)acrylate (PMFA), which have excellent insulating properties, but show discernible dielectric constants and polarities. On hydrophobic BCB-assisted PMFA blend dielectrics (approximately 400 nm thick), organic field-effect transistors (OFET) and complementary inverters were demonstrated using pentacene and N,N′-ditridecylperylene-3,4,9,10-tetracarboxylic diimide (PTCDI-C13) as semiconducting channels. The values of field-effect mobilities showed up to 0.33 cm2 V−1 s−1 (for pentacene) and 0.85 cm2 V−1 s−1 (for PTCDI-C13), respectively. In addition, these based complementary inverter was successfully demonstrated with a high voltage gain of ca. 41, specifically, onto the 10 wt% BCB-assisted PMFA dielectric optimized to achieve a hydrophobic and smooth surface by vertically phase-separating the immiscible polymers.