Search results for "Telechelic polymer"

Mechanical and thermal behaviour of networks with “flexible” and “rigid” chains

1996

“Rigid-rod” telechelics were synthesized via repetitive Diels-Alder reaction of biscyclohexadienes and bis(1,2,4-triazoline-3,5-diones). The bistriazolinediones were used in slight excess. The rigidity of the building blocks and the molecular weight were varied. Various amounts of these reactive telechelics are used to crosslink cis-1,4-polybutadiene. The mechanical and the thermal properties of these two-component networks were investigated by stress-strain, differential scanning calorimetry and dynamic-mechanical measurements. The occurrence of microphase separation between the “rigid” and the “flexible” components is discussed to explain the properties of these materials.

“Functional Poly(ethylene glycol)”: PEG-Based Random Copolymers with 1,2-Diol Side Chains and Terminal Amino Functionality

2010

A series of poly(ethylene glycol-co-isopropylidene glyceryl glycidyl ether) (P(EO-co-IGG)) random copolymers with different fractions of 1,2-isopropylidene glyceryl glycidyl ether (IGG) units was synthesized. After acidic hydrolysis a new type of "functional PEGs", namely poly(ethylene glycol-co-glyceryl glycerol) (P(EO-co-GG)) was obtained. Using an initiator that releases a terminal amino moiety after deprotection, functional end groups with orthogonal reactivity to the in-chain groups were obtained. All polymers showed narrow molecular weight distributions (1.07-1.19), and control of the molecular weights was achieved in the range 5000-30 000 g/mol. Random incorporation of both comonomer…

Synthesis of linear and three-arm star tert-chlorine-telechelic polyisobutylenes by a two-step conventional laboratory process

1997

A two-step conventional laboratory process was developed for the synthesis of mono- and difunctional linear and three-arm star tert-chlorine-telechelic polyisobutylenes (PIB) with desired molecular weights (MW) and narrow molecular weight distribution (MWD) by living carbocationic polymerization (LCCP). This polymerization method applies easy to handle operations and chemicals. LCCP of isobutylene (IB), was carried out in CH2Cl2 as solvent and with BCl3 as coinitiator in the first step to obtain soluble low MW PIB prepolymer with narrow MWD. This was followed by addition of hexane, TiCl4 and additional monomer in the second step to prepare PIBs with desired MW and narrow MWD in practically …

Endfunctional Polymers by Functionalization of Living Cationic Chain Ends with 1,1-Diphenylethylene

1995

Abstract A new functionalization method has been developed for the synthesis of 2,2-diphenylvinyl(DPV)-telechelic polyisobutylene (PIB). First, living carbocationic polymerization (LCCP) of isobutylene (IB) is quantitatively end-quenched with a nonpolymerizable olefin, 1,1-diphenylethylene (DPE). This process yields a mixture of diphenyl substituted vinyl and tertiary chlorine endgroups. Treatment of the resulting polymer with potassium-tert-butoxide (tBuOK) leads to the quantitative formation of DPV-telechelic PIB which is a potential macroinitiator precursor for living anionic polymerizations.

Secondary Structure-Driven Hydrogelation Using Foldable Telechelic Polymer-Peptide Conjugates.

2018

The synthesis of ABA and ABA' triblock polyethylene glycol-and polysarcosine-peptide conjugates is reported. The A/A' peptides are based on phenylalanine(F)-histidine(H) pentapeptide sequences FHFHF, which promote pH-switchable β-sheet self-assembly into nanorods in water. Only parallel β-sheet-driven folding and intermolecular assembly using ABA triblock polymer-peptide conjugates leads to interstrand cross-linking and hydrogelation, highlighting the impact of supramolecular interactions-directed structure formation at the nano- and mesoscopic level.

Chain-extending of Hydroxytelechelic Polybutadiene: Synthesis and Characterization

2010

Extension of hydroxytelechelic polybutadiene oligomers ( 3200 g/mol) is performed in mild conditions, in order to avoid backbone modifications, using succinic anhydride or methylenedicyclohexyl diisocyanate. The two routes present significative extension of the initial oligomers. Extension through the anhydride route, in the presence of DCC and DMAP, leads to new hydroxytelechelic oligomers ( 8000 g/mol). Extension through the diisocyanate route, catalyzed by DBTL at 65°C leads to hydroxytelechelic oligomers of higher average molecular weight ( 20000 g/mol). New materials are characterized by FTIR/1H-NMR and changes in their Tg according to , are discussed. The influence of reaction time on…

Thermo- and Light-Responsive Polymers Containing Photoswitchable Azobenzene End Groups

2009

Telechelic thermo- and light-responsive polymers based on poly(oligo(ethylene glycol) methyl ether methacrylate) P(OEGMA) with azobenzene functionalities at the end groups were synthesized. In a reversible addition−fragmentation chain transfer (RAFT) polymerization using a functionalized chain transfer agent (CTA) containing a pentafluorophenyl (PFP) activated ester, oligo(ethylene glycol) methyl ether methacrylate (OEGMA, Mn ∼ 300 g mol−1) could successfully be polymerized with good control over molecular weight, very high conversions, and narrow molecular weight distributions. Polymers derived from this CTA possessed an activated ester at the α-end of the polymer chain as well as a dithio…

Oligo(ether sulfones). 3. Block Copolymers via Condensation Reactions of Telechelic Oligo(ether sulfones) Bearing Phenolic Endgroups and Oligomeric α…

1999

Synthesis of Reactive Telechelic Polymers Based on Pentafluorophenyl Esters

2008

A diazo initiator and a chain transfer agent (CTA), both containing a pentafluorophenyl (PFP) activated ester, were synthesized. In a RAFT polymerization using the functionalized chain transfer agent (PFPCTA), methyl methacrylate (MMA), diethylene glycol monomethyl ether methacrylate (DEGMA), poly(ethylene glycol) monomethyl ether methacrylate (PEGMA), and lauryl methacrylate (LMA) could successfully be polymerized into homopolymers and diblock copolymers with good control over molecular weight, very high conversions, and narrow molecular weight distributions. Polymers derived from the PFP-CTA possessed an activated ester at the R-end of the polymer chain, which could be reacted with amines…

Synthesis of molecularly uniform model oligomers for 1,5-naphthalene diisocyanate and 1,4-butanediol based polyurethanes by using the 3,5-di-tert-but…

1997

A modified benzyloxycarbonyl (BOC) protective group, the 3,5-di-tert-butyl substituted BOC (3,5-tBBOC) group, was introduced to the stepwise synthesis of molecularly uniform oligourethanes based on 1,5-naphthalene diisocyanate (NDI) and 1,4-butanediol (BDO) for the protection of the amino functions of the starting material 1,5-naphthalene-diamine (NDA). The tert-butyl substituents of the 3,5-tBBOC group significantly improved the solubility of the intermediate products in the oligourethane synthesis. Thus, applying this modified protective group, reactions could be carried out, which were not possible with the conventional BOC group, due to the insolubility of the compounds in all suitable …