Browsing by Author "Peng, Chi-How"

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Cylindrical micelles of a POSS amphiphilic dendrimer as nano-reactors for polymerization
(2018-02-21)
Weng, Jing-Ting
;
Yeh, Tso-Fan
;
Samuel, Ashok Zachariah
;
Huang, Yi-Fan
;
Sie, Jyun-Hao
A low generation amphiphilic dendrimer, POSS-AD, which has a POSS core and eight amphiphilic arms, was synthesized and used as a nano-reactor to produce well-defined polymer nano-cylinders. Confirmed by small-angle X-ray scattering (SAXS), Raman and NMR spectrometry, monodispersed cylindrical micelles that contain a hydrophilic cavity with a diameter of 2.09 nm and a length of 4.26 nm were produced via co-assembling POSS-AD with hydrophilic liquids, such as H2O and HEMA in hydrophobic solvents. Taking the HEMA/POSS-AD cylindrical micelles as nano-reactors, polymerization of HEMA within the micelles results in polymer nano-cylinders (POSS-AD NPs) with a diameter of 2.24 nm and a length of 5.02 nm. The study confirmed that despite the inability to maintain specific shape in solution, low generation dendrimers form well-defined nano-containers or nano-reactors, which relies on co-assembling with hydrophilic guest molecules. These nano-reactors are robust enough to maintain their shape during the polymerization of the guest molecules. Polymer nano-cylinders with dimensions less than 10 nm can thus be produced from the HEMA/POSS-AD micelles. Since the chemical structure of low-generation dendrimers and the contents of the co-assembled nano-reactors can be easily adjusted, the concept holds the potential for the further developments of low-generation amphiphilic dendrimers.
Fabrication of Multicomponent Polymer Nanostructures Containing PMMA Shells and Encapsulated PS Nanospheres in the Nanopores of Anodic Aluminum Oxide Templates
(2015-03-01)
Ko, Hao-Wen
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Chi, Mu-Huan
;
Chang, Chun-Wei
;
Su, Chun-Hsien
;
Wei, Tzu-Hui
Multi-component polymer nanomaterials have attracted great attention because of their applications in areas such as biomedicine, tissue engineering, and organic solar cells. The precise control over the morphologies of multi-component polymer nanomaterials, however, is still a great challenge. In this work, the fabrication of poly(methyl methacrylate)(PMMA)/polystyrene (PS) nanostructures that contain PMMA shells and encapsulated PS nanospheres is studied. The nanostructures are prepared using a triple solution wetting method with anodic aluminum oxide (AAO) templates. The nanopores of the templates are wetted sequentially by PS solutions in dimethylformamide (DMF), PMMA solutions in acetic acid, and water. The compositions and morphologies of the nanostructures are controlled by the interactions between the polymers, solvents, and AAO walls. This work not only presents a feasible method to prepare multi-component polymer nanomaterials, but also leads to a better understanding of polymer-solvent interactions in confined geometries.
Hybridization of CMRP and ATRP: A Direct Living Chain Extension from Poly(vinyl acetate) to Poly(methyl methacrylate) and Polystyrene
(2015-10-13)
Chen, Ya-Jo
;
Wu, Bing-Jyun
;
Wang, Fu-Sheng
;
Chi, Mu-Huan
;
Chen, Jiun-Tai
Cobalt-mediated radical polymerization (CMRP) was used to prepare well-defined poly(vinyl acetate) (PVAc) as the macroinitiator in the reverse atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) and styrene (Sty) for the synthesis of block copolymers of PVAc-b-PMMA and PVAc-b-PSty with linearly increased molecular weight and smoothly shifted gel permeation chromatography (GPC) traces. The chain extension from PVAc to PMMA or PSty via the hybridization of CMRP and ATRP required neither a difunctional initiator nor further chain-end modification and was as simple as regular chain extension in the reverse ATRP process. Because the cobalt complex bonded to the chain end of PVAc was dissociated during the ATRP process, this method also efficiently solved the issue of metal removal in the CMRP process.
Shaping the Light: The Key Factors Affecting the Photophysical Properties of Fluorescent Polymer Nanostructures
(2016-12)
Chi, Mu-Huan
;
Su, Chun-Hsien
;
Cheng, Ming-Hsiang
;
Chung, Pei-Yun
;
Peng, Chi-How
To manipulate the functions of nanomaterials more precisely for diverse applications, the controllability and critical influencing factors of their properties must be thoroughly investigated. In this work, the macroscopic and microscopic effects are studied on the photophysical properties of various pyrene-ended poly(styrene-block-methyl methacrylate) nanostructures. Fluorescent polymer nanospheres, nanorods, and nanotubes are prepared by different template-based methods using anodic aluminum oxide membranes. Chain arrangements and conformations are determined as the key factors affecting the photophysical properties of the fluorescent polymer nanostructures. This work not only gives a deeper understanding of the effects on the photophysical properties of polymer nanomaterials influenced by morphologies, chain arrangements, and chain conformations, but also provides a reference for designing proper fluorescent nanostructures for specific applications.
Solvent-Induced Dewetting on Curved Substrates: Fabrication of Porous Polymer Nanotubes by Anodic Aluminum Oxide Templates
(2015-09-08)
Chi, Mu-Huan
;
Chang, Chun-Wei
;
Ko, Hao-Wen
;
Su, Chun-Hsien
;
Lee, Chih-Wei
Dewetting of polymer thin films triggered by thermal or solvent annealing on flat substrates have been widely studied. Research on dewetting of polymer thin films on curved substrate, however, has been rarely investigated and remains a great challenge, especially for dewetting induced by solvent annealing. In this work, we study the dewetting of polymer thin films on curved substrates by annealing poly(methyl methacrylate) (PMMA) nanotubes in cylindrical nanopores of anodic aluminum oxide (AAO) templates via dimethylformamide (DMF) vapor treatment. After solvent annealing, dewetting of the curved PMMA thin films is induced, resulting in the formation of porous PMMA nanotubes. By changing the experimental conditions such as annealing time, solvent quality, and molecular weight of polymer, the hole sizes of the PMMA nanotubes can be controlled or even prevented. To demonstrate the universality of this method, porous nanotubes of polystyrene (PS) and fluorescent pyrene-ended PMMA (Py-PMMA) are also fabricated. This work not only provides a better understanding of dewetting of polymer thin films on curved substrates but also offers a promising new way to prepare porous polymer nanotubes with controllable hole sizes.