Stimuli Responsive and Self Assembly Behaviors of Poly(Oxypropylene)-Amine Graft Poly(Styrene-co-Maleic Anhydride) Comb-Like Copolymers.
Date Issued
2008
Date
2008
Author(s)
Hsu, Yen-Chi
Abstract
In this article, copolymer oligo-(oxypropylene) - amine graft poly(styrene- co-maleic anhydride) is prepared by various structure. The synthesized comb-branched copolymer is stimuli responsive and could be used as a polymer template for preparing silver fiber by self-assembly. There are three chapters to describe the (a) temperature responsive, (b) pH responsive and (c) the self assembly behavior of these series of comb-branched copolymer. hapter 1. Temperature- and pH-Responsive Properties of Oligo-(oxypropylene) - Amine Graft Poly(Styrene-co-Maleic Anhydride) series of temperature- and pH-responsive copolymers were synthesized by grafting poly(oxypropylene)-diamines (POP-amine) onto poly(styrene-co-maleic anhydride) (SMA). Owing to the presence of multiple POP-pendants and their expressive hydrogen bonding properties, the copolymers in water exhibited Lower Critical Solution Temperature (LCST) behavior in the range of 11-49 oC depending on the POP segmental weight and the SMA backbone structures. Furthermore, the co-existence of -NH2 termini and amidoacid functionalities rendered the copolymers responsive to environmental pH changes. Structural variation in the SMA backbone, particularly the monomer ratio of styrene to maleic anhydride, POP length, and amine multiplicity, may significantly alter the shapes of copolymer aggregation in responding to the environmental pH and temperature. The responsiveness was observed on their morphological changes by tapping mode atomic force microscopy (TM-AFM) on mica film surface and also fluorescent properties in aqueous solution. hapter 2. Stimuli-Responsive Micelles from Comblike Copolymers of Poly (Styrene-co-Maleic Anhydride) Graft Poly(oxypropylene)-Amines he pH-responsive micellization of the copolymers, prepared from the grafting reaction of poly(oxypropylene)-amine of 400 g/mol molecular weight (POP400) onto poly(styrene-co-maleic anhydride) (SMA) backbone, is presented. The comb-branched copolymers are consisted of oligo-styrene/ethylene in the backbone and amide-linkages with polar pendants of carboxylic acid, oxylpropylene-segment, and primary amine. The co-existence of –COOH and –NH2 in multiplicity rendered the SMA-POP copolymer responsive to pH and temperature. Conformational changes from random coil at pH 10 to spherical micelle with an average 50 nm diameter at pH 8.3 were observed by particle size analysis in water at ambient temperature. At the isoelectric point (IEP pH 8.2) of SMA3000-POP400, the polymer self-assembled into spherical polymer particles with the diameter range from 100 to 500 nm and stable after removing waters. In forming film, the surface exhibited different hydrophilic/hydrophobic properties, demonstrating the surface contact angle of 23o at pH 9.3 and 58o at pH 8.1. Inversion of micellar formation, depending the pH environment, through the non-covalent bonding of SMA backbone aggregation and water interaction with the pendent COOH and NH2 is proposed. hapter 3. Hierarchical Self-Assemblies of Silver Rectangles and Fibrous Wires by Copolymer Templates and Visible-LightWe observed the self-assemblies of silver rectangles and fibrous wires from silver nitrate reduction in the presence of copolymer template and visible-light. The copolymer in comb-like structure was facilely prepared from the grafting reaction of poly(oxyalkylene)-monoamine (POA-amine) onto the poly(styrene-co-maleic anhydride) (SMA). By dissolving AgNO3 in the aqueous copolymer and standing for days under visible light, unique formation of rectangle-shaped silver wires in the dimension of 1.6-6.4μm in diameter and 100-370μm in length was obtained. The formation process was monitored by UV-visible spectroscopy, particle size analysis, scanning electron microscope (SEM) and transmission electron microscope (TEM), showing first appearance of silver particles is 10 nm in diameter, followed by the intermediate rectangles (0.6-1.0 μm in width and 0.4 μm in length) and ultimately the precipitated micrometer wires. The growth of the precipitated silver fibers was accelerated by the exposure of visible light as the photo-reducing energy source. The microscale fibers are characterized to have silver content over 95 wt % (80 mole %) and with the conductivity of 170 S/cm.
Subjects
thermal-responsive
comb-branched copolymer
pH-responsive
self-assembly
silver fibers
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-97-D94549006-1.pdf
Size
23.53 KB
Format
Adobe PDF
Checksum
(MD5):adfa34dbd341684714148bb06ba3e2c1