Star Polymer Synthesis Using Hexafluoropropylene Oxide as an Efficient Multifunctional Coupling Agent

Switek, Karen A.; Bates, Frank S.

doi:10.1021/ma035936h

Cited by 13 publications

(7 citation statements)

References 21 publications

(42 reference statements)

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“…The formation of these higher molecular weight products suggests that multiple reactions of HEMI-PLLA can occur with one CS molecule. Each of the three fatty acid residues in CS can contain conjugated double bonds, and the multiple additions of HEMI-PLLA to CS are likely responsible for the additional products observed in the SEC trace . Heating either HEMI-PLLA-1 or HEMI-PLLA-20 without CS does not alter its SEC elution curve, confirming that the higher molecular weight products were not a result of HEMI-PLLA self-coupling.…”

Section: Resultsmentioning

confidence: 82%

Reactive Compatibilization of Poly(l-lactide) and Conjugated Soybean Oil

2010

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Ring-opening bulk polymerization of L-lactide using N-2-hydroxyethylmaleimide (HEMI) as the initiator and tin(II) 2-ethylhexanoate as the catalyst produced a reactive end-functionalized poly-(L-lactide) (HEMI-PLLA). Melt blends of HEMI-PLLA and conjugated soybean oil (CS) were prepared. HEMI-PLLA underwent a Diels-Alder reaction with the CS to high conversion, coupling the two immiscible components. Up to three HEMI-PLLA molecules reacted with one CS molecule to create products with varying architecture that acted as compatibilizers for the melt blend. Blends of HEMI-PLLA and 5 wt % CS resulted in a greater than 17-fold increase in elongation to break compared to PLLA homopolymer and more than doubled the elongation to break compared to a 5 wt % CS blend with unreactive PLLA. Analysis of the blend morphology indicated that the in situ formation of the compatibilizer decreased the CS droplet diameter compared to unreactive binary blends and that an optimum droplet diameter exists for toughening PLLA with CS.

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Section: Resultsmentioning

confidence: 82%

Reactive Compatibilization of Poly(l-lactide) and Conjugated Soybean Oil

2010

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“…Functionalized initiators also facilitate the synthesis of telechelic and heterotelechelic polymers, functionalized block polymers, and star-shaped polymers with functional groups on each arm terminus . The use of the functional initiator 3-( tert -butyldimethylsilyloxy)-1-propyllithium (TBDMSPrLi) was reported in the synthesis of a variety of polymers with various molecular architectures, including polyisoprene, ,− polybutadiene, ,,,, poly(methyl methacrylate), , and poly(1,3-cyclohexadiene), to yield hydroxyl chain-end-functionalized polymers.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of Star-Shaped Poly(ethylene-co-propylene) Polymers Bearing Terminal Self-Complementary Multiple Hydrogen-Bonding Sites

2006

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The polymerization of isoprene was initiated with 3-(tert-butyldimethylsilyloxy)-1-propyllithium (TBDMSPrLi), which contained a silyl-protected hydroxyl functionality. Living poly(isoprenyllithium) with controlled molecular weight and narrow molecular weight distribution coupled efficiently with divinylbenzene to form well-defined star-shaped polymers. Both linear and star-shaped polymers were subsequently hydrogenated to poly(ethylene-co-propylene) and deprotected quantitatively to yield terminal primary hydroxyl functionality. High conversions of hydroxyl functionality to the 2-ureido-4[1H]-pyrimidinone (UPy) quadruple hydrogen-bonding group were achieved using isocyanate coupling and subsequent reaction with 6-methylisocytosine. Nonfunctionalized and UPy-functionalized linear and star-shaped poly(ethylene-co-propylene)s were characterized using 1H NMR spectroscopy, dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), tensile testing, and melt rheology. The observed glass transition temperatures were independent of molecular architecture for the UPy-functionalized polymers and nonfunctionalized analogues using both DSC and DMA. Tensile testing revealed the UPy-functionalized star polymers (UPy-Star) exhibited a higher Young's modulus and lower percent elongation at failure compared to the UPy-telechelic polymers with M n of 24 000 g/mol (UPy-24K-T) analogues. UPy-Star polymer exhibited a rubbery plateau region over a well-defined frequency range, and in contrast, the UPy-functionalized linear polymers were in the terminal flow regime, which suggested greater association for the star-shaped polymers. In addition, complex viscosity data revealed a non-Newtonian behavior for the star-shaped polymers in contrast to linear analogues, which is also consistent with a highly associated structure.

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“…19 Finally, Hillmyer et al were able to analyze hydroxylfunctionalized polyisoprene star polymers with molar masses up to 9000 g mol -1 , but spectra with isotopic resolution were not obtained. 20 In general, branched polymers are often too complex to be analyzed with MALDI-TOF due to a distribution in the number of arms, differences in end-group functionality, and broad molar mass distributions (MMD).…”

Section: Introductionmentioning

confidence: 99%