Triblock copolymers are playing important roles in nanomaterial synthesis, and the nanomaterial forming mechanisms need to be studied in detail. In situ liquid cell transmission electron microscopy （TEM） is a powerf...Triblock copolymers are playing important roles in nanomaterial synthesis, and the nanomaterial forming mechanisms need to be studied in detail. In situ liquid cell transmission electron microscopy （TEM） is a powerful tool for real time observation of the dynamic growth behavior of nanomaterials in liquid with high resolution, and could be used for the above task. Here we report the observation of the growth and self-assembly of Pt nanoclusters with the aid of an ethylene oxide-propylene oxide-ethylene oxide triblock copolymer （PEO-PPO-PEO） F 127 using in situ liquid cell TEM, with the nanocluster growth and formation procedures being tracked. Nano objects were seen to appear, drift and rotate with time, and then form into certain shaped nanoclusters under the electron beam irradiation. Further interestingly, in the thicker liquid layer region, the nanoclusters appeared to be fluffy, with average size keeping increase with time, while in the thinner region, the clusters were thinner, and got densified with time. The difference in precursor availability due to liquid layer thickness and charging effects is attributed to such a phenomenon.展开更多
The bottom-up filling capabilities of electroless copper plating bath with an addition of additives, such as poly- ethylene glycol （PEG）, polypropylene glycol （PPG） and triblock copolymers of PEG and PPG with ethy...The bottom-up filling capabilities of electroless copper plating bath with an addition of additives, such as poly- ethylene glycol （PEG）, polypropylene glycol （PPG） and triblock copolymers of PEG and PPG with ethylene oxide terminal blocks termed EPE, were investigated by the cross-sectional scanning electron microscopy （SEM） obser- vation of sub-micrometer trenches. Though three additives had inhibition for electroless copper deposition, the suppression degrees of three additives were different. EPE-2000 had the strongest suppression for electroless copper deposition, and the suppression of PEG-2000 was the weakest. The bottom-up filling capability of electroless copper was investigated in a plating bath containing different additives with the concentration of 2.0 mg/L. The cross-sectional SEM observation indicated the trenches with the width of 280 nm and the depth of 475 nm were all completely filled by the plating bath with an addition of EPE-2000, but the trenches were not completely filled by the plating bath with an addition of PEG-2000 or PPG-2000, and some voids appeared. Linear sweep voltammetry measurement indicated that three additives all inhibited the cathodic reduction reaction and the anodic oxidation reaction, and the inhibition of EPE-2000 was the strongest among three additives, which agreed with that of the deposition rate of electroless copper. Significant differences in surface roughness of deposited copper film were observed by UV-visible near-infrared for different suppressors, and the bright and smooth of deposited copper film were in accordance with the inhibition of three additives.展开更多
In this paper, microphase behavior of an ABC triblock copolymer, polystyrene-block-poly（2-vinylpyridine）-block- poly（ethylene oxide）, namely PS-b-P2VP-b-PEO, was systematically studied during spin-coating and solv...In this paper, microphase behavior of an ABC triblock copolymer, polystyrene-block-poly（2-vinylpyridine）-block- poly（ethylene oxide）, namely PS-b-P2VP-b-PEO, was systematically studied during spin-coating and solvent vapor annealing based on various parameters, including the types of the solvent, spin speed and thickness. The morphological features and the microdomain location of the different blocks were characterized by atomic force microscope （AFM） and high resolution transmission electron microscopy （HRTEM）. With increasing thickness, the order-order transition from nanopores array to the pattern of nanostripes was observed due to microdomain coarsening. These processes of pattern transformation were based on the selectivity of toluene for different blocks and on the contact time between solvent molecules and the three blocks. This work provides different templates for preparation of gold nanoparticle array on silicon wafer, which can be adopted as an active surface-enhanced Raman scattering （SERS） substrate for poly（3-hexylthiophene） （P3HT）.展开更多
A series of azobenzene containing side-on liquid crystalline ABA triblock copolymers were investigated. This triblock series possesses the same central liquid crystal block B and various lengths of the amorphous block...A series of azobenzene containing side-on liquid crystalline ABA triblock copolymers were investigated. This triblock series possesses the same central liquid crystal block B and various lengths of the amorphous block A. Transmission electron microscopy （TEM）, small angle X-rays and neutron scattering （SAXS and SANS） were used to study their morphologies. After annealing the samples over weeks at a temperature within the nematic temperature range of block B, different morphologies （disordered, lamellar, perforated layer and hexagonal cylinder） were observed by TEM. The alignment behavior of these azo triblock copolymers in the magnetic field for artificial muscle application, as well as the phase period and the order-disorder transition （ODT） were studied in situ by SANS.展开更多
The effect of flexible spacer length on the liquid crystalline property of ABA-type triblock copolymers containing azobenzene groups was investigated. For the study, the monomers, n-[4-(4-ethoxyphenylazo)phenoxy]alkyl...The effect of flexible spacer length on the liquid crystalline property of ABA-type triblock copolymers containing azobenzene groups was investigated. For the study, the monomers, n-[4-(4-ethoxyphenylazo)phenoxy]alkyl methacrylates with varying methylene groups (n = 0, 2, 6) were used to synthesize a series of azobenzene-containing amphiphilic triblock copolymers PAnC–PEG–PAnC by atom transfer radical polymerization (ATRP). Differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and one-dimensional X-ray diffraction (1D WAXD) have shown that the glass transition temperatures of these copolymers decreased with increasing n, PA0C–PEG–PA0C has no mesophase, while both PA2C–PEG–PA2C and PA6C–PEG–PA6C have a nematic mesophase. These differences derive from the length of spacer groups between the polymer backbone and side-chain LC monomers.展开更多
Co-assembly of ABC linear triblock copolymer/nanoparticle into bump-surface multicompartment hybrids in selective solvent was studied through self-consistent field theory （SCFT） simulation. Results from three-dimens...Co-assembly of ABC linear triblock copolymer/nanoparticle into bump-surface multicompartment hybrids in selective solvent was studied through self-consistent field theory （SCFT） simulation. Results from three-dimensional SCFT simulation showed that the hybrid morphology depended on the length and number of grafted chains, whereas the number and shape of bumps relied on nanoparticle size. Moreover, the simulation results showed that the length and number of grafted chains had equivalent effect on hybrid morphology. Calculated results indicated that entropy was a more important factor than enthalpy in the co-assembly.展开更多
文摘Triblock copolymers are playing important roles in nanomaterial synthesis, and the nanomaterial forming mechanisms need to be studied in detail. In situ liquid cell transmission electron microscopy （TEM） is a powerful tool for real time observation of the dynamic growth behavior of nanomaterials in liquid with high resolution, and could be used for the above task. Here we report the observation of the growth and self-assembly of Pt nanoclusters with the aid of an ethylene oxide-propylene oxide-ethylene oxide triblock copolymer （PEO-PPO-PEO） F 127 using in situ liquid cell TEM, with the nanocluster growth and formation procedures being tracked. Nano objects were seen to appear, drift and rotate with time, and then form into certain shaped nanoclusters under the electron beam irradiation. Further interestingly, in the thicker liquid layer region, the nanoclusters appeared to be fluffy, with average size keeping increase with time, while in the thinner region, the clusters were thinner, and got densified with time. The difference in precursor availability due to liquid layer thickness and charging effects is attributed to such a phenomenon.
基金Project supported by the National Natural Science Foundation of China （No. 20873080）.
文摘The bottom-up filling capabilities of electroless copper plating bath with an addition of additives, such as poly- ethylene glycol （PEG）, polypropylene glycol （PPG） and triblock copolymers of PEG and PPG with ethylene oxide terminal blocks termed EPE, were investigated by the cross-sectional scanning electron microscopy （SEM） obser- vation of sub-micrometer trenches. Though three additives had inhibition for electroless copper deposition, the suppression degrees of three additives were different. EPE-2000 had the strongest suppression for electroless copper deposition, and the suppression of PEG-2000 was the weakest. The bottom-up filling capability of electroless copper was investigated in a plating bath containing different additives with the concentration of 2.0 mg/L. The cross-sectional SEM observation indicated the trenches with the width of 280 nm and the depth of 475 nm were all completely filled by the plating bath with an addition of EPE-2000, but the trenches were not completely filled by the plating bath with an addition of PEG-2000 or PPG-2000, and some voids appeared. Linear sweep voltammetry measurement indicated that three additives all inhibited the cathodic reduction reaction and the anodic oxidation reaction, and the inhibition of EPE-2000 was the strongest among three additives, which agreed with that of the deposition rate of electroless copper. Significant differences in surface roughness of deposited copper film were observed by UV-visible near-infrared for different suppressors, and the bright and smooth of deposited copper film were in accordance with the inhibition of three additives.
基金supported by the National Natural Science Foundation of China(Nos.51273048 and 51203025)Natural Science Foundation of Guangdong Province(No.S2012040007725)
文摘In this paper, microphase behavior of an ABC triblock copolymer, polystyrene-block-poly（2-vinylpyridine）-block- poly（ethylene oxide）, namely PS-b-P2VP-b-PEO, was systematically studied during spin-coating and solvent vapor annealing based on various parameters, including the types of the solvent, spin speed and thickness. The morphological features and the microdomain location of the different blocks were characterized by atomic force microscope （AFM） and high resolution transmission electron microscopy （HRTEM）. With increasing thickness, the order-order transition from nanopores array to the pattern of nanostripes was observed due to microdomain coarsening. These processes of pattern transformation were based on the selectivity of toluene for different blocks and on the contact time between solvent molecules and the three blocks. This work provides different templates for preparation of gold nanoparticle array on silicon wafer, which can be adopted as an active surface-enhanced Raman scattering （SERS） substrate for poly（3-hexylthiophene） （P3HT）.
基金financially supported by the French Embassy in China(Beijing) to Wei Deng(Bourse doctorale en altemance 2004-2007)
文摘A series of azobenzene containing side-on liquid crystalline ABA triblock copolymers were investigated. This triblock series possesses the same central liquid crystal block B and various lengths of the amorphous block A. Transmission electron microscopy （TEM）, small angle X-rays and neutron scattering （SAXS and SANS） were used to study their morphologies. After annealing the samples over weeks at a temperature within the nematic temperature range of block B, different morphologies （disordered, lamellar, perforated layer and hexagonal cylinder） were observed by TEM. The alignment behavior of these azo triblock copolymers in the magnetic field for artificial muscle application, as well as the phase period and the order-disorder transition （ODT） were studied in situ by SANS.
文摘The effect of flexible spacer length on the liquid crystalline property of ABA-type triblock copolymers containing azobenzene groups was investigated. For the study, the monomers, n-[4-(4-ethoxyphenylazo)phenoxy]alkyl methacrylates with varying methylene groups (n = 0, 2, 6) were used to synthesize a series of azobenzene-containing amphiphilic triblock copolymers PAnC–PEG–PAnC by atom transfer radical polymerization (ATRP). Differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and one-dimensional X-ray diffraction (1D WAXD) have shown that the glass transition temperatures of these copolymers decreased with increasing n, PA0C–PEG–PA0C has no mesophase, while both PA2C–PEG–PA2C and PA6C–PEG–PA6C have a nematic mesophase. These differences derive from the length of spacer groups between the polymer backbone and side-chain LC monomers.
基金supported by the National Natural Science Foundation of China for General Program(No. 21274145)
文摘Co-assembly of ABC linear triblock copolymer/nanoparticle into bump-surface multicompartment hybrids in selective solvent was studied through self-consistent field theory （SCFT） simulation. Results from three-dimensional SCFT simulation showed that the hybrid morphology depended on the length and number of grafted chains, whereas the number and shape of bumps relied on nanoparticle size. Moreover, the simulation results showed that the length and number of grafted chains had equivalent effect on hybrid morphology. Calculated results indicated that entropy was a more important factor than enthalpy in the co-assembly.
