Search results for " Polymer"
showing 10 items of 3533 documents
Hetero-Multifunctional Poly(ethylene glycol) Copolymers with Multiple Hydroxyl Groups and a Single Terminal Functionality
2009
Hetero-multifunctional poly(ethylene glycol-co-glycerol) random copolymers with multiple hydroxyl functionalities and a single terminal functionality have been prepared by copolymerization of ethylene oxide (EO) and ethoxy ethyl glycidyl ether (EEGE) with the use of a suitable initiator, introducing a protected amino group or a double bond, respectively. Acidic deprotection was used for removal of the acetal protecting groups in the chain, and the terminal amino group was regenerated by catalytic hydrogenation. A series of copolymers with narrow polydispersity was obtained, varying comonomer fractions from 3 to 67% and molecular weights in the range of 5 000-32 000 g · mol(-1) (1.05 < $\ove…
Networks of Partially Hydrogenatedcis-1,4-Polybutadiene and ‘Rigid Rods’
1996
Networks of 'flexible' and 'rigid' chains were synthesized. As 'flexible' component we have used different partially hydrogenated cis-1,4-polybutadiene. The 'rigid' component was synthesized from bis(1,2,4-triazoline-3,5-dione)s and biscyclohexadienes via repetitive Diels-Alder reaction. A slight excess of bis(1,2, 4-triazoline-3,5-dione)s leads to polymers with 1,2,4-triazoline-3,5-dione end groups, which can easily react with the partially hydrogenated cis-1,4-polybutadiene. The influence of the extent of hydrogenation and the amount of crosslinker on the mechanical and thermal behaviour is described.
Synthesis of new polymers via Diels–Alder reaction. III. Biscyclohexadienephthalimides as dienes
1993
Difunctional cyclohexadienes with dihydrophthalimide central unitsand phenyl side groups to increase solubility are used as bisdienes in repetitive Diels-Alder polyadditions with bis(4-(1,2,4,-triazoline-3,5-dione-4-yl)phenyl)methane as a difunctional dienophile. The polymers show good solubility in CH 2 Cl 2 and CHCl 3 . Non-stoichiometric Diels-Alder polyaddition with slight excess of the bistriazolinedione provides the possibility of synthesizing telechelics with highly reactive triazolinedione end groups
Heterotelechelic Ring-Opening Metathesis Polymers
2009
By combining sacrificial synthesis with the vinyl lactone termination technique, heterotelechelic polymers were synthesized. The nonterminating nature of sacrificial synthesis was utilized to introduce a hydroxyl group at the start of the polymer chain. Lactone termination was used to functionalize the chain ends with aldehydes or carboxylic acids. The synthesis of well-defined heterotelechelic polymers was thus accomplished employing the Grubbs’ first generation catalyst as the initiator. The living nature of this polymerization allowed for precise control over the molecular weight and guaranteed full functionalization of both polymer chain ends. The presence of the functional groups is sh…
Synthesis of Heterotelechelic α,ω Dye-Functionalized Polymer by the RAFT Process and Energy Transfer between the End Groups
2009
The synthesis of a vinyl polymer with two different fluorescent dye end groups using reversible addition-fragmentation chain transfer (RAFT) polymerization is described. Use of a pentafluorophenyl (PFP) activated ester chain transfer agent (CTA) provided a polymer with an R end group that was reactive toward amines and a dithioester ω end group. The R PFP ester was amidated with Oregon Green Cadaverin. This did not harm the ω dithioester, which was subsequently aminolyzed with an excess of n-propylamine in the presence of Texas Red-2-sulfonamidoethyl methanethiosulfonate, resulting in a disulfide bond connecting the second dye to the polymer chain. Excess dyes and side products were removed…
Sacrificial Synthesis of Hydroxy-Telechelic Metathesis Polymers via Multiblock-Copolymers
2009
The synthesis of well-defined telechelic ring-opening metathesis polymers has been achieved by Sacrificial Synthesis. With the formation of cleavable triblock-copolymers, precise control over the molecular weight and the degree of functionalization was achieved. Introducing cleavable monomers that can be addressed separately, sequential deprotection was accomplished which opened the path to more sophisticated polymeric materials bearing different substituents at their respective chain ends. Sacrificial penta- and heptablock-copolymers are also presented which allow the synthesis of well-defined telechelic polymers in good yields and significantly improved initiator efficiency.
Synthesis of new soluble polybenzyls by Friedel-Crafts reactions
1999
Soluble polybenzyls were prepared by a catalytic electrophilic Friedel-Crafts type polycondensation between α,α'-dichloro-p-xylene and substituted (by an alkyl or an alkoxy side-chain) mesitylene. The influence of the length of the side-chain on the solubility of the polymer was examined. The polymers were found to be soluble in common organic solvents. Polymer characterizations were made by 13 C nuclear magnetic resonance spectroscopy (NMR), size exclusion chromatography (SEC), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and elemental analysis.
Effect of small amounts of poly(lactic acid) on the recycling of poly(ethylene terephthalate) bottles
2011
Abstract Poly(ethylene terephthalate) (PET) is one of the most used commodity polymers, especially for food and beverage applications, and its recycling is of great importance because of the possible use in the textile and construction industries. On the other hand, the interest in biodegradable polymers has led, in recent years, to the use of materials such as poly(lactic acid) (PLA) also in the food and beverage industry. The presence of small amounts of PLA in the PET waste can significantly affect the post-consumer recycling process. In this work, the effect of the presence of small amounts of PLA on the recycling of PET bottles is investigated by rheological, mechanical, morphological …
Grafting of Molecularly Imprinted Polymer Films on Silica Supports Containing Surface-Bound Free Radical Initiators
2001
Silica particles containing surface-bound free radical initiators have been used as supports for the grafting of thin films of molecularly imprinted polymers (MIPs). This technique offers a means of fine-tuning the layer thickness for improved kinetic properties or enhanced capacity in chromatographic or sensor applications. Thus prepared MIPs imprinted with l-phenylalanine anilide, have been characterized by FT-IR spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), elemental analysis, fluorescence microscopy, and scanning electron microscopy (SEM), providing evidence concerning the reproducibility in each step and the quantity and quality of the grafted…
Nonisothermal elongational behavior of blends with liquid crystalline polymers
1994
Measurements of melt strength and breaking stretching ratio of several blends of thermoplastic polymers with liquid crystalline polymers are presented. The melt strength behavior depends not only on the viscosity of the blends but also on the temperature dependence of the viscosity. In particular, even if the viscosities of the blends are, at the extrusion temperature, lower than that of the thermoplastic matrices, the melt strength can be larger than that of the pure thermoplastics if its viscosity-temperature curve exceeds that of the matrices far from the solidification temperature. This behavior allows one to spin or film blow these blends despite the low viscosity.