Interfacial reaction between two immiscible polymers can cause changes in the interfacial morphology. We demonstrated this using an aliphatic amine terminated polystyrene (PS−NH2) and anhydride terminated poly(methyl methacrylate) (PMMA−ah). Interfacial morphologies were recorded using transmission electron microscopy and atomic force microscopy. Coupling of PS−NH2 and PMMA−ah induced flat interfaces to roughen with a magnitude of roughness around a few hundred nanometers. These morphological changes were explained in terms of the decrease of interfacial tension due to the creation of block copolymers and the thermal fluctuation induced deformations at interfaces.

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In the preceding publication, we showed that the hyperbranched polystyrenes (HBPS) synthesized as part of this study may be viewed as starlike molecules with a high branch density, which are either unentangled or weakly entangled. In this paper, the role of architecture, especially the branch density, on the rheological and orientation behavior is investigated using simultaneous, quantitative stress and flow birefringence measurements in the melt state. Linear PS and eight-arm symmetric PS stars follow the stress-optical rule (SOR) over a wide dynamic range, with the stress-optical coefficient (C) governed by the arm molecular weight. When the branch density is "moderate" (greater than ∼20 arms), there is only a hint of nonterminal behavior in the viscoelastic moduli, while the C drops by 30% compared to a star with eight arms of comparable length. When the branch density is "high" (∼50 arms), and the arms are unentangled, the nonterminal behavior in G* is clearly apparent, and there is a dramatic breakdown in the stress-optical rule in these homopolymer melts. The quantitative birefringence measurements suggest that the "excess" birefringence may be due to the "form" contributions from the core-shell structure. Such a structure may be formed by the preferential radial stretching of the chain segments near the core, as suggested by other studies on hyperstars. For comparable chain density, the core would be bigger than the shell when the arm length is smaller. Therefore, the 5K-HBPS exhibits a more severe breakdown compared to the 10K-HBPS.

Polymers bearing a single alkyl chloride at the chain end were synthesized using anionic polymerization techniques. Specifically, living polystyrene (PS) anions were treated with commercially available (4-chlorobutyl)dimethylchlorosilane and found to react chemoselectively at the electrophilic silicon atom. 1 The pendant alkyl chloride on these PS chains was subsequently transformed into alkyl azide and aliphatic amine functionalities. The gel permeation chromatograms for the synthesized polymers were found to have relatively narrow molecular weight distributions (Mw/Mn < 1.09) after the end-capping reaction. Nuclear magnetic resonance (NMR) spectroscopy and gel permeation chromatography (GPC) studies were used to quantify the degree of functionalization.Polymers bearing reactive functional groups represent an intriguing class of materials having potential application in several areas including surface modification, lubrication, catalysis, drug delivery, and compatibilization of polymer blends. 2 We are interested in blending and have found that in situ block copolymer formation via a chemical reaction (reactive blending) can be an effective means to compatibilize polymer blends. 2,3 On an industrial level, randomly functionalized copolymers are often used as blend compatibilizers (e.g. Nylon 6, and EP-g-maleic anhydride). 4 In these systems a complex mixture of graft copolymer compatibilizers necessarily results, making it difficult to investigate important fundamental aspects related to polymer blending. For this reason we are initially studying the reactivity of immiscible monofunctional polymers that form simple A-B diblocks during melt blending.It is desirable to make block copolymers rapidly during blending; therefore, fast coupling reactions are attractive. Of the reactive pairs we have investigated, the primary aliphatic amine/cyclic anhydride system has the most promising reaction kinetics. 5 We have observed extremely fast melt-coupling reactions (homogenous and heterogeneous) and remarkable reactive selfassembly phenomena with this reactive pair. 6 These exciting initial results led us to develop new, straightforward methods for synthesizing polymers bearing a single, terminal, reactive functional group. 7 Specifically, we have designed synthetic methods that utilize readily available materials as trapping agents for living polymer anions and that are amenable to large-scale. We have also used a simplified procedure for purifying all monomers and solvents used in our anionic polymer synthesis. Passing the neat materials [styrene and cyclohexane here; and methacrylates, isoprene, (Me 2 -SiO) 3 in cyclohexane, diphenylethylene, toluene, THF, and heptane in other instances] through basic alumina after pretreatment with a reactive drying reagent (e.g., LAH, Et 3 Al, or CaH 2 ) provides starting materials of sufficiently high purity for many anionic polymerizations. In contrast to the more commonly used multiple bulb-to-bulb distillations using break-seal and/or high vacuum apparatus for purification and t...

Polymers bearing a single succinic anhydride at the chain end were synthesized using anionic polymerization techniques. Specifically, the living anions of poly(methyl methacrylate) (PMMA), polystyrene (PS), polyisoprene (PI), and poly(vinylpyridine) (PVP) were found to exclusively undergo a 1,4-conjugate addition reaction with di-tert-butyl maleate. Only a single maleate adds. The gel permeation chromatograms for the synthesized polymers were found to have very narrow molecular weight distributions (Mw/Mn < 1.15) after the end-capping reaction. Pyrolysis (235°C, 2-12 h) of the resulting substituted di-tert-butyl succinate ester efficiently produced the related succinic anhydride functional polymers in the case of PMMA and PS. The functionality of these polymers (f g 0.81) was determined following derivatization reactions with various amines. Nuclear magnetic resonance (NMR) spectroscopy and gel permeation chromatography (GPC) of the resulting amides permits quantification of the extent of functionalization. Upon melt blending (200°C) an anhydride terminal PMMA (29 kg/mol) with an amino terminal PS (18.5 kg/mol) all of the monofunctional homopolymers were converted to PS-PMMA diblock within 20 min (GPC and transmission electron microscopy, TEM). A lamellar morphology (TEM) was obtained after further annealing of this sample (72 h).