Search results for "Copolymer"
showing 10 items of 1003 documents
Tetrahydrofuran: More than a “Randomizer” in the Living Anionic Copolymerization of Styrene and Isoprene: Kinetics, Microstructures, Morphologies, an…
2020
The statistical anionic copolymerization of isoprene (I) and styrene (S) is commonly used to synthesize tapered block copolymers, enabling control of the phase behavior by adjusting the order–disor...
Adsorption of di-and triblock copolymers with functionalized butadiene-styrene blocks from dilute solution
1995
Abstract The adsorption behaviour of functionalized polystyrene-block-polybutadiene diblock copolymers, P(S-b-B), and polybutadiene-block-polystyrene-block-polybutadiene triblock copolymers, P(B-b-S-b-B), from dilute solutions in toluene onto silicon wafers was investigated by means of null-ellipsometry. Polar 4-(3,5-dioxo- 1,2,4-triazolidin-4-yl) benzoic acid groups (urazole groups) were attached randomly to the butadiene blocks. The PS blocks and the PB blocks adsorb not on the substrate surface, but only on the polar functional groups. It was verified that the adsorbed amount does not depend on the number of functional groups nor on the degree of polymerization of the polybutadiene block…
The glass transition of mixtures of polystyrene with alkyl-terminated oligostyrene — experimental evidence for microphase separation in a polymer ble…
1995
Mixtures of high molecular weight polystyrene (P n = 961.5 ; T g = 373 K) and sec-butyl-terminated oligostyrene (P n = 10.6 ; T g = 302 K) show a dependence of the glass transition on the composition (i.e., number-average molecular weight) which cannot be described by the classic equations of Fox & Flory or Kanig & Ueberreiter. Addition of small amounts of the oligostyrene strongly decreases the glass transition, and above an oligomer content of 40 wt.-% the glass transition remains constant within experimental error. This behavior can be attributed to the unfavorable interactions between the alkyl-terminated oligomer and the high molecular weight PS. As a result the oligomer is a bad solve…
Influence of the Copolymer Content on the Miscibility, Phase Behaviour and Morphology of a DGEBA/Polystyrene/Styrene-co-Maleic Anhydride Ternary Blend
2009
The miscibility, phase behaviour and morphology of ternary systems, formed by a DGEBA-based epoxy resin, polystyrene (PS) and styrene-co-maleic anhydride (SMA) copolymers have been investigated through phase diagrams. The analysis has been done in the absence and in the presence of 4,4'-methylene bis(2,6-diethyl aniline) (MDEA) as curing agent. In both cases, the influence of the copolymer content on blend compatibility, has been discussed. The results show that miscibility is enhanced by the presence of SMA copolymer in the blend and as the MA content in the copolymer is increased (from 7 to 14wt.-%), due to specific H-bonding interactions between the H-donor hydroxyl groups on the epoxy r…
An All-ROMP Route to Graft Copolymers
2007
A new versatile synthesis strategy for macromonomers has been developed that uses the living ring-opening metathesis polymerization (ROMP) with commercial Grubbs first generation ruthenium initiators. Homopolymers as well as diblock copolymers were end-functionalized with norbornene derivatives to serve as macromonomers. The graft copolymerization of the macromonomers was also carried out employing ROMP. Well-defined and highly functional graft copolymers are accessible by this new synthetic route.
RAFT Polymerization of Pentafluorophenyl Methacrylate: Preparation of Reactive Linear Diblock Copolymers
2005
Reversible addition fragmentation chain transfer (RAFT) polymerization of pentafluorophenyl methacrylate (PFMA) was carried out in the presence of cumyldithiobenzoate and 4-cyano-4-((thiobenzoyl)sulfanyl)pentanoic acid, respectively. These chain transfer agents with 2,2'-azoisobutyronitrile (AIBN) as initiator yielded the active ester polymer poly(PFMA) with M n up to 17000 g . mol -1 and low polydispersity index (M w /M n <1.2). Kinetic analysis using 19 F NMR spectroscopy and gel permeation chromatography (GPC) measurements showed controlled polymerization behavior for both chain transfer agents. Successful preparation of linear diblock copolymers consisting of an active ester block and m…
Amphipolar Core−Shell Cylindrical Brushes as Templates for the Formation of Gold Clusters and Nanowires
2002
Methacryloyl end-functionalized block copolymers consisting of styrene and vinyl-2-pyridine were polymerized to poly(block co-macromonomer)s with a much higher main chain than side chain degree of ...
Local and Subchain Relaxation of Polyisoprene in Multiblock Copolymers with a Tapered Interface
2020
We report on the local and (sub-) chain dynamics in a new class of tapered multiblock copolymers synthesized by the repeated statistical living anionic copolymerization of a mixture of isoprene and...
Synthesis of a polystyrene-arm-polybutadiene-arm-poly(methyl methacrylate) triarm star copolymer
1996
The straightforward synthesis of a polystyrene-arm-polybutadiene-arm-poly(methyl methacrylate) triarm star copolymer has been successfully realized by a sequence of reactions which involves the sequential addition of a living polybutadienyllithium to a polystyrene macromonomer with a terminal 1,1-diphenylethylene unit and subsequent polymerization of methyl methacrylate. The high-molecular-weight polystyrene-arm-polybutadiene-arm-poly(methyl methacrylate) star copolymer shows microphase separation into three phases.
Synthesis of Amphiphilic Block Copolypept(o)ides by Bifunctional Initiators: Making PeptoMicelles Redox Sensitive.
2015
In this work, the synthesis of polypeptoid-block-polypeptide copolymers (block copolypept(o)ides) based on bifunctional initiators is described, which introduces a distinct chemical entity at the connection between both blocks. With a view towards redox-sensitive block copolypept(o)ides, a cystamine-based initiator was used to synthesize polysarcosine macroinitiators with degrees of polymerization (Xn) between 100 and 200 displaying monomodal molecular weight distributions and dispersities (Đ) around 1.1 as determined by size exclusion chromatography. Block copolypept(o)ides with a poly(γ-t-butyloxycarbonyl-L-glutamate) (PGlu(O(t) Bu)) block (Xn = 25 or 50) were synthesized by controlled N-…