A synthetic approach to attain precisely controlled methyl branching in polyethylene is
described. Model polymers based on polyethylene have been created using acyclic diene metathesis
(ADMET) chemistry as the mode of polymerization. Differential scanning calorimetry (DSC) was employed
to examine the thermal behavior (melting point, heat of fusion, glass transition temperature) of five model
polyethylene polymers wherein a methyl branch was placed on each 9th, 11th, 15th, 19th, and 21st carbon
respectively along the backbone. Melting points and heats of fusion decrease as the frequency of precise
methyl branching increases. On the other hand, the β glass transition and its change in specific heat are
independent of branch frequency. Comparisons of these model polymers with industrial polyethylene
samples demonstrate that this polycondensation approach will provide the basis for a better understanding
of the morphology, crystalline structure, and thermodynamics of the crystallization process of the most
abundant synthetic macromolecule in the world, polyethylene.
Previously unknown unsaturated polyethers from acyclic, ether-containing dienes have first been obtained via acyclic diene metathesis (ADMET) polymerization in the presence of the catalyst W(CHt-Bu) (N-2,6-CsHs-i-Pr~) [OCMe(CFs)2]2. Polymer yields are high, and number-average molecular weights up to an = 15 000-18 OOO are observed. Structural assignments of the polymers are based on 1% NMR and 1H NMR spectroscopy, IR spectroscopy, and elemental analysis. The polymerizability of the ether-containing a,o-diene appears to be a function of the distance between the ether oxygen and the metathesizing double bond in the monomer. An ether-containing diene has also been copolymerized with 1,9-decadiene.
sponse analyzer (EG&G, Model 1025). The complex impedance plots of the samples were recorded in the frequency range from 1 to 10 5 Hz. The cationic transference numbers, t+, were determined by the steady-state current technique proposed by Bruce and Vincent [28]. The details are given by Reiche et al [29]. Ni was used as a working electrode (A= 0.5 cm 2 ) and Li as counter and reference electrode for cyclic voltammetry.Solid-State NMR: One-dimensional 7 Li static, 27 Al magic-angle spinning, and 1 H/ 29 Si cross-polarization magic-angle spinning experiments were performed on a Bruker ASX500 spectrometer. The 27 Al spectra were recorded using a spinning speed of 8±14 kHz and a small tip angle. The spinning speed for the 1 H/ 29 Si cross-polarization magic-angle spinning experiments was 4±5 kHz, and the cross-polarization contact time was 2 ms. The 1 H/ 13 C WISE experiments were carried out on a Bruker MSL300 spectrometer with a cross-polarization contact time of 200 ls.
The synthesis of poly(γ-benzyl-L-glutamate)-b-polyoctenamer-b-poly(γ-benzyl-L-glutamate) (13) and poly(γ-benzyl-L-glutamate)-b-polyethylene-b-poly(γ-benzyl-L-glutamate) (14) triblock copolymers is described. R,ω-Bisamino-terminated polyoctenamer (5) was used to prepare a difunctional macroinitiator (12) used for the living polymerization of γ-benzyl-L-glutamic acid-N-carboxyanhydride (Glu-NCA) to form the triblock copolymers. 5 was synthesized by acyclic diene metathesis polymerization of 1,9-decadiene (1) in the presence of 11-phthalimido-1-undecene (2) and Grubbs' metathesis catalyst, RuCl2(dCHPh)-( PCy3)2 (3). Deprotection of the resulting phthalimide end-functionalized polymers (4) was performed, leading to difunctional 5 with number-average functionalities close to two. These methods allow the controlled preparation of polypeptide/(hydrocarbon polymer) block architectures with good control over the chain lengths of both domains and without formation of homopolypeptide contaminants.
The use of electrophiles (isocyanates, isothiocyanates, acid chlorides) to cap the N-terminal ends of polypeptides and the use of isocyanates to prepare poly(γ-benzyl-L-glutamate)-b-(nonpeptide polymer) block copolymers are described. This chemistry was also used to prepare poly(ethylene glycol)where polymer ) polyoctenamer, poly(ethylene glycol), or poly(dimethylsiloxane). These R,ω-diamino-terminated polymers (polymer) were used to prepare difunctional macroinitiators for the living polymerization of γ-benzyl-L-glutamic acid-N-carboxyanhydride (Glu NCA) to form triblock copolymers that were subsequently capped with isocyanate terminated poly(ethylene glycol) to give the pentablock copolymers. These methods allow the facile functionalization of the N-terminal ends of polypeptides from NCA polymerizations. They also were shown to allow the controlled preparation of "rod-coil" polypeptide-(nonpeptide polymer) multiblock architectures with good control over the chain lengths of the domains and without formation of homopolypeptide contaminants.
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