Browsing by Author "Chen, Wan-Chun"

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Self-assembly of an A-B diblock copolymer blended with a C homopolymer and a C-D diblock copolymer through hydrogen bonding interaction
(2010-08-19)
Chen, Wan-Chun
;
Kuo, Shiao-Wei
;
Chang, Feng-Chih
;
應用化學系
;
Department of Applied Chemistry
In this study, we investigated the miscibility, phase behavior, and self-assembled nanostructures formed from the immiscible crystalline-amorphous diblock copolymer poly(epsilon-caprolactone-b-4-vinyl pyridine) (PCL-b-P4VP, A-B) when blended with the homopolymer poly(vinyl phenol) (PVPh, C) and the diblock copolymer poly(vinyl phenol-b-styrene) (PVPh-b-PS, C-D). Long-range-ordered microphase separation was difficult to achieve in the PCL-b-P4VP/PVPh (A-B/C) blend system because PVPh interacted with both the P4VP and PCL blocks simultaneously through hydrogen bonding interactions. In contrast, we observed sharp, multiple orders of diffraction in the SAXS profiles of the PCL-b-P4VP/PVPh-b-PS (A-B/C D) blend system, indicating that perfect microphase separation occurred because the incorporation of the PS block induced the PVPh block to hydrogen bond preferentially with the P4VP block. This simple A-B/C-D (PCL-b-P4VP/PVPh-b-PS) diblock copolymer mixture exhibited self-assembly behavior (a three-lamella phase) similar to that of a corresponding ABC triblock copolymer. (C) 2010 Elsevier Ltd. All rights reserved.
Self-Assembly Structures through Competitive Interactions of Crystalline-Amorphous Diblock Copolymer/Homopolymer Blends: Poly(epsilon-caprolactone-b-4-vinyl pyridine)/Poly(vinyl phenol)
(2009-05-26)
Chen, Wan-Chun
;
Kuo, Shiao-Wei
;
Lu, Chu-Hua
;
Jeng, U-Ser
;
Chang, Feng-Chih
A series of immiscible crystalline-amorphous diblock copolymers, poly(epsilon-caprolactone)-b-(4-vinyl pyridine) (PCL-b-P4VP), were synthesized through combination of sequential ring-opening and controlled living free radical (nitroxide-mediated) polymerizations and then blended with poly(vinyl phenol) (PVPh) homopolymer. Miscibility and self-assembly morphologies mediated by hydrogen-bonding interactions of this new A-B/C type polymer blend are discussed in detail. Self-assembly morphologies of these immiscible PCL-b-P4VP diblock copolymers change through competitive hydrogen-bonding interactions with the increase of PVPh contents The SAXS profiles also reveal a sharp primary peak and highly long-range order reflections such as cylinder or sphere structure at relatively lower PVPh content, which is consistent with TEM images. DSC, WAXD, and FT-IR analyses provide positive evidence that the pyridine group of P4VP is a significantly stronger hydrogen-bond acceptor than the carbonyl group of PCL with the hydroxyl group of PVPh and results in the excluded and confined PCL phase.
Self-assembly through competitive interactions of miscible diblock copolymer/homopolymer blends: Poly(vinylphenol-b-methyl methacrylate)/poly(vinylpyrrolidone) blend
(2008-02-26)
Chen, Wan-Chun
;
Kuo, Shiao-Wei
;
Jeng, U-Ser
;
Chang, Feng-Chih
;
應用化學系
We have investigated a new type A-b-B/C blend system, poly(vinylphenol-b-methyl methacrylate)/ poly(vinylpyrrolidone) (PVPh-b-PMMA)/PVP, where PVPh-b-PMMA block (A-b-B) copolymer, PVPh/PVP (A/C), and PMMA/PVP (B/C) blends are all miscible through hydrogen bond interaction or dipole-dipole, interaction. Because of the significantly stronger hydrogen bond interaction between PVPh and PVP than that between PVPh and PMMA, this miscible PVPh-b-PMMA copolymer becomes immiscible up on blending with 20-60 wt % PVP (27-56 wt % PMMA in the blend system) and can self-assemble to form ordered morphologies. Results from small-angle X-ray scattering (SAXS) and TEM consistently indicate that different compositions of PVPh-b-PMMA/PVP blends induce different microphase separation structures such as hexagonal and lamellar phases. However, sharp and multiple orders of diffraction are absent from the SAXS profiles, indicating relatively. limited sizes of the ordered domains. Large polydispersity in the molecular weight of PVP and small differences in the interaction parameters of the three components of PVPh, PMMA, and PVP are attributed to be the main reasons that limit the microphase separation in this blend system.