Formation of 12-nm Nanodot Pattern by Block Copolymer Self-Assembly Technique

2011 ◽  
Vol 497 ◽  
pp. 122-126 ◽  
Author(s):  
Miftakhul Huda ◽  
Takuro Tamura ◽  
You Yin ◽  
Sumio Hosaka
Keyword(s):  
Molecular Weight ◽  
Quantum Dot ◽  
Self Assembly ◽  
Microphase Separation ◽  
Experimental Result ◽  
Storage Device ◽  
Pdms Layer ◽  
Pdms Film ◽  
Assembly Technique ◽  
Total Molecular Weight

In this work, we studied the fabrication of 12-nm-size nanodot pattern by self-assembly technique using high-etching-selectivity poly (styrene)-poly (dimethyl-siloxane) (PS-PDMS) block copolymers. The necessary etching duration for removing the very thin top PDMS layer is unexpectedly longer when the used molecular weight of PS-PDMS is 13.5-4.0 kg/mol (17.5 kg/mol total molecular weight) than that of 30.0-7.5 kg/mol (37.5 kg/mol total molecular weight). From this experimental result, it was clear that PS-PDMS with lower molecular weight forms thicker PDMS layer on the air/polymer interface of PS-PDMS film after microphase separation process. The 22-nm pitch of nanodot pattern by self-assembly holds the promise for the low-cost and high-throughput fabrication of 1.3 Tbit/inch2storage device. Nanodot size of 12 nm also further enhances the quantum-dot effect in quantum-dot solar cell.

Self-Assembled Nanodot Fabrication by Using Diblock Copolymer

2010 ◽  
Vol 459 ◽  
pp. 120-123 ◽  
Author(s):  
Miftakhul Huda ◽  
You Yin ◽  
Sumio Hosaka
Keyword(s):  
Molecular Weight ◽  
Solar Cell ◽  
Quantum Dot ◽  
Diblock Copolymer ◽  
Silicon Substrate ◽  
Pdms Layer ◽  
Large Area ◽  
Dimethyl Siloxane ◽  
Self Assembled

In this study, we investigate self-assembled large-area nanodot fabrication on a silicon substrate using poly(styrene)-poly(dimethyl-siloxane) (PS-PDMS) for the application to quantum dot solar cell. By optimizing the PS-PDMS concentration by 2% and the volume of PS-PDMS solutions by 20 μL/cm2 dropped to silicon substrate, nanodots with a pitch size of 33 nm and a diameter of 23 nm are achieved with the molecular weight of 30,000-7,500. It is found that the dropped volume of PS-PDMS solution correlated to the thickness of spin-coated PS-PDMS layer has a great effect on the size and the pattern morphology.

Dendronised Polymers as Templates for In Situ Quantum Dot Synthesis

2020 ◽  
Vol 73 (7) ◽  
pp. 658
Author(s):  
Alaa M. Munshi ◽  
Jessica A. Kretzmann ◽  
Cameron W. Evans ◽  
Anna M. Ranieri ◽  
Zibeon Schildkraut ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Quantum Dot ◽  
Targeted Drug Delivery ◽  
Self Assembly ◽  
Fourth Generation ◽  
Narrow Molecular Weight Distribution ◽  
Targeted Drug ◽  
Shape Characteristics ◽  
High Degree

The utility of dendrimers as effective carriers for targeted drug delivery and imaging has been facilitated by a high degree of molecular uniformity, narrow molecular weight distribution, tunable size and shape characteristics, and multivalency. Dendrimer–quantum dot (QD) nanocomposites have traditionally been synthesised by electrostatic self-assembly of preformed dendrimers and QDs, but higher generations are associated with limited flexibility and increased cytotoxicity. In this paper, we report the fabrication of CdTe QD nanoparticles using a dendronised linear copolymer bearing thiolated fourth-generation poly(amido amine) (PAMAM) dendrons as the capping and stabilising agent. We demonstrate this approach enables synthesis of nanocomposites with aqueous and photophysical stability.

Freeze-Thawed Hybridized Preparation with Biomimetic Self-Assembly for a Polyvinyl Alcohol/Collagen Hydrogel Created for Meniscus Tissue Engineering

2014 ◽  
Vol 21 ◽  
pp. 17-33 ◽  
Author(s):  
Puttiporn Puttawibul ◽  
Soottawat Benjakul ◽  
Jirut Meesane
Keyword(s):  
Molecular Weight ◽  
Self Assembly ◽  
Molecular Interaction ◽  
Morphological Structure ◽  
Sem Analysis ◽  
Porous Network ◽  
Molecular Weights ◽  
Collagen Hydrogel ◽  
Meniscus Tissue ◽  
Assembly Technique

Freeze-thawed hybridized preparation and the biomimetic self-assembly technique were used to fabricate hydrogel as tissue engineered scaffolds for meniscus tissue. Because of the advantages of both techniques, they were hybridized together as an interesting preparation for hydrogel. Three molecular weights (high, medium, and low) of PVA were prepared in a biomimetic solution before formation into hydrogel by freeze-thawing. The most suitable molecular weight PVA for hydrogel formation was chosen to be mixed with collagen. PVA, PVA/collagen, and collagen were prepared in biomimetic solutions and freeze-thawed into hydrogels. The hydrogels were analyzed and characterized by FTIR, DSC, and SEM. FTIR characterization indicated that high molecular weight PVA formed molecular interaction better than the other molecular weights, and PVA molecules formed molecular interaction with collagen molecules via –OH and C=O groups. DSC characterization showed that the hybridized preparation of freeze-thawing and biomimetic self-assembly kept the characteristics of PVA and collagen. SEM analysis demonstrated that the morphological formation of PVA/collagen was hybridized during freeze-thawing and collagen self-assembly. The morphological structure was organized into a porous network structure. The porous structure showed a rough wall that was formed by the hybridized structure of the crystal domain dispersed in amorphous and collagen self-assembly.

Morphological studies of linear (AB)n multiblock copolymers and their blends

1992 ◽  
Vol 50 (1) ◽  
pp. 384-385
Author(s):  
Richard J. Spontak ◽  
Steven D. Smith ◽  
Arman Ashraf
Keyword(s):  
Electron Microscopy ◽  
Microphase Separation ◽  
Multiblock Copolymers ◽  
First Order ◽  
Morphological Studies ◽  
Transmission Electron ◽  
First Order Phase Transition ◽  
Covalently Bonded ◽  
Total Molecular Weight ◽  
First Order Phase

Block copolymers are composed of sequences of dissimilar chemical moieties covalently bonded together. If the block lengths of each component are sufficiently long and the blocks are thermodynamically incompatible, these materials are capable of undergoing microphase separation, a weak first-order phase transition which results in the formation of an ordered microstructural network. Most efforts designed to elucidate the phase and configurational behavior in these copolymers have focused on the simple AB and ABA designs. Few studies have thus far targeted the perfectly-alternating multiblock (AB)n architecture. In this work, two series of neat (AB)n copolymers have been synthesized from styrene and isoprene monomers at a composition of 50 wt% polystyrene (PS). In Set I, the total molecular weight is held constant while the number of AB block pairs (n) is increased from one to four (which results in shorter blocks). Set II consists of materials in which the block lengths are held constant and n is varied again from one to four (which results in longer chains). Transmission electron microscopy (TEM) has been employed here to investigate the morphologies and phase behavior of these materials and their blends.

scholarly journals High-efficiency CO2 separation using hybrid LDH-polymer membranes

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xiaozhi Xu ◽  
Jiajie Wang ◽  
Awu Zhou ◽  
Siyuan Dong ◽  
Kaiqiang Shi ◽  
...  
Keyword(s):  
Self Assembly ◽  
High Efficiency ◽  
Transmission Rate ◽  
Spray Coating ◽  
Separation Performance ◽  
Pdms Layer ◽  
Operational Testing ◽  
Enhanced Solubility ◽  
Double Hydroxide

AbstractMembrane-based gas separation exhibits many advantages over other conventional techniques; however, the construction of membranes with simultaneous high selectivity and permeability remains a major challenge. Herein, (LDH/FAS)n-PDMS hybrid membranes, containing two-dimensional sub-nanometre channels were fabricated via self-assembly of unilamellar layered double hydroxide (LDH) nanosheets and formamidine sulfinic acid (FAS), followed by spray-coating with a poly(dimethylsiloxane) (PDMS) layer. A CO2 transmission rate for (LDH/FAS)25-PDMS of 7748 GPU together with CO2 selectivity factors (SF) for SF(CO2/H2), SF(CO2/N2) and SF(CO2/CH4) mixtures as high as 43, 86 and 62 respectively are observed. The CO2 permselectivity outperforms most reported systems and is higher than the Robeson or Freeman upper bound limits. These (LDH/FAS)n-PDMS membranes are both thermally and mechanically robust maintaining their highly selective CO2 separation performance during long-term operational testing. We believe this highly-efficient CO2 separation performance is based on the synergy of enhanced solubility, diffusivity and chemical affinity for CO2 in the sub-nanometre channels.

scholarly journals Quadruple Hydrogen Bond-Containing A-AB-A Triblock Copolymers: Probing the Influence of Hydrogen Bonding in the Central Block

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4705
Author(s):  
Boer Liu ◽  
Xi Chen ◽  
Glenn A. Spiering ◽  
Robert B. Moore ◽  
Timothy E. Long
Keyword(s):  
Hydrogen Bonding ◽  
Self Assembly ◽  
Microphase Separation ◽  
Triblock Copolymers ◽  
Random Copolymer ◽  
Thermomechanical Properties ◽  
Structure Property ◽  
Scanning Calorimetry ◽  
Central Block ◽  
Quadruple Hydrogen Bonding

This work reveals the influence of pendant hydrogen bonding strength and distribution on self-assembly and the resulting thermomechanical properties of A-AB-A triblock copolymers. Reversible addition-fragmentation chain transfer polymerization afforded a library of A-AB-A acrylic triblock copolymers, wherein the A unit contained cytosine acrylate (CyA) or post-functionalized ureido cytosine acrylate (UCyA) and the B unit consisted of n-butyl acrylate (nBA). Differential scanning calorimetry revealed two glass transition temperatures, suggesting microphase-separation in the A-AB-A triblock copolymers. Thermomechanical and morphological analysis revealed the effects of hydrogen bonding distribution and strength on the self-assembly and microphase-separated morphology. Dynamic mechanical analysis showed multiple tan delta (δ) transitions that correlated to chain relaxation and hydrogen bonding dissociation, further confirming the microphase-separated structure. In addition, UCyA triblock copolymers possessed an extended modulus plateau versus temperature compared to the CyA analogs due to the stronger association of quadruple hydrogen bonding. CyA triblock copolymers exhibited a cylindrical microphase-separated morphology according to small-angle X-ray scattering. In contrast, UCyA triblock copolymers lacked long-range ordering due to hydrogen bonding induced phase mixing. The incorporation of UCyA into the soft central block resulted in improved tensile strength, extensibility, and toughness compared to the AB random copolymer and A-B-A triblock copolymer comparisons. This study provides insight into the structure-property relationships of A-AB-A supramolecular triblock copolymers that result from tunable association strengths.

scholarly journals Impact of Macrodiols on the Morphological Behavior of H12MDI/HDO-Based Polyurethane Elastomer

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2060
Author(s):  
Shazia Naheed ◽  
Mohammad Zuber ◽  
Mahwish Salman ◽  
Nasir Rasool ◽  
Zumaira Siddique ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Contact Angle ◽  
Chain Length ◽  
Microphase Separation ◽  
Soft Segment ◽  
Group Identification ◽  
Degree Of Crystallinity ◽  
Polyurethane Elastomers ◽  
Hard Segments ◽  
Morphological Behavior

In this study, we evaluated the morphological behavior of polyurethane elastomers (PUEs) by modifying the soft segment chain length. This was achieved by increasing the soft segment molecular weight (Mn = 400–4000 gmol−1). In this regard, polycaprolactone diol (PCL) was selected as the soft segment, and 4,4′-cyclohexamethylene diisocyanate (H12MDI) and 1,6-hexanediol (HDO) were chosen as the hard segments. The films were prepared by curing polymer on Teflon surfaces. Fourier transform infrared spectroscopy (FTIR) was utilized for functional group identification in the prepared elastomers. FTIR peaks indicated the disappearance of −NCO and −OH groups and the formation of urethane (NHCOO) groups. The morphological behavior of the synthesized polymer samples was also elucidated using scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. The AFM and SEM results indicated that the extent of microphase separation was enhanced by an increase in the molecular weight of PCL. The phase separation and degree of crystallinity of the soft and hard segments were described using X-ray diffraction (XRD). It was observed that the degree of crystallinity of the synthesized polymers increased with an increase in the soft segment’s chain length. To evaluate hydrophilicity/hydrophobicity, the contact angle was measured. A gradual increase in the contact angle with distilled water and diiodomethane (38.6°–54.9°) test liquids was observed. Moreover, the decrease in surface energy (46.95–24.45 mN/m) was also found to be inconsistent by increasing the molecular weight of polyols.

Synthesis of poly(methyl methacrylate)-b-poly(acrylic acid) by DPE method

e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Dong Chen ◽  
Ruixue Liu ◽  
Zhifeng Fu ◽  
Yan Shi
Keyword(s):  
Molecular Weight ◽  
Acrylic Acid ◽  
Methyl Methacrylate ◽  
Diblock Copolymer ◽  
Self Assembly ◽  
Gel Permeation Chromatography ◽  
Amphiphilic Diblock Copolymer ◽  
Poly Methyl Methacrylate ◽  
Copolymer Poly ◽  
Poly Acrylic Acid

AbstractAmphiphilic diblock copolymer poly(methyl methacrylate)-b-poly(acrylic acid) (PMMA-b-PAA) was prepared by 1,1-diphenylethene (DPE) method. Firstly, free radical polymerization of methyl methacrylate was carried out with AIBN as initiator in the presence of DPE, giving a DPE-containing PMMA precursor with controlled molecular weight. tert-Butyl acrylate (tBA) was then polymerized in the presence of the PMMA precursor, and PMMA-b-PtBA diblock copolymer with controlled molecular weight was prepared. Finally, amphiphilic diblock copolymer PMMA-b-PAA was obtained by hydrolysis of PMMA-b-PtBA. The formation of PMMA-b-PAA was confirmed by 1H NMR spectrum and gel permeation chromatography. Transmission electron microscopy and dynamic light scattering were used to detect the self-assembly behavior of the amphiphilic diblock polymers in methanol.

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