Synthesis and Characterization of Thermally Stable Polymers through Anionic Polymerization of tert-Alkyl Crotonates

Abstract

ABSTRACT:Some alkyl crotonates bearing tert-alkyl groups, i.e., lert-butyl, tert-amyl, 1-adamantyl and 3,5-dimethyl-1-adamantyl crotonates were prepared and polymerized with sec-butyllithium as an anionic catalyst in toluene or THF. The resulting polymers were confirmed to consist of poly(substituted methylene) structure by IR and NMR spectroscopies. The polymers bearing adamantyl groups had more resistance to hydrolysis, whereas the tert-butyl and amyl esters were readily hydrolyzed. The introduction of the adamantyl groups also increased glass transition temperature and decomposition temperature of the polymer. It was revealed that the polymers bearing the tert-butyl and amyl esters decomposed via a two-step mechanism, resulting in the formation of poly(crotonic acid) accompanied with elimination of corresponding olefins from the ester groups, but the polymers containing adamantyl groups showed excellent thermal stability.

ADMET Polymerization of Amino‐Acid‐Based Diene

“…The 1,2‐disubstituted olefins are expected to have a lower reactivity than vinyl double bonds but in fact appear to be inert toward radical thiol‐ene chemistry, unlike the double bonds in 1,4‐polybutadiene (cross‐linking), polynorbornenes or other ROMP prepared polymers (quantitative addition of thiols) . A nucleophilic or base‐catalyzed thiol‐Michael addition of MMP to 4 was not attempted because it was expected to fail or complicated by side reactions (as known for the anionic polymerization of alkyl crotonates) . Double bonds were, however, quantitatively consumed during the reaction with bromine.…”

“…Double bond isomerization is seemingly to fail [ 20 ] or complicated by side reactions (as known for the anionic polymerization of alkyl crotonates). [ 22 ] Double bonds were, however, quantitatively consumed during the reaction with bromine.…”

Polyhydroxyalkanoates: Chemical Modifications Toward Biomedical Applications

“…97 The presence of the β-methyl substituent on the unsaturated group induces steric hindrance with the α-substituent. 98 However, the carboxylic acid terminated PHB oligomers produced by thermal degradation can be subsequently modified to give methacrylic PHA macromonomers. The graft copolymers containing PHAs can obtained by copolymerization of PHAs macromonomers with other (meth)acrylic family members.…”

Group-Transfer Polymerization of Various Crotonates Using Organic Acid Catalysts

“…However, β-substituted α,β-unsaturated carboxylate monomers, such as alkyl crotonates and alkyl cinnamates, are not easily polymerized. , In fact, alkyl crotonates cannot be polymerized by the common radical initiators of azobisisobutyronitrile (AIBN) and rac -2,2′-azobis­(4-methoxy-2,4-dimethylvaleronitrile) (V-70L) (see Supporting Information). Moreover, in the past two decades, synthetic methods for poly­(alkyl crotonate)­s (PRCrs) have been infrequently studied. − In one study, Ute et al showed that transition-metal Lewis acids, such as HgI 2 , catalyzed the GTP of various n -alkyl crotonates using 1-trimethylsiloxyl-1-methoxy-2-methyl-1-propene (MTS) as an initiator. − In this study, we attempted the GTP of various alkyl crotonates with organic catalysts. Herein, we demonstrate a synthetic procedure for PRCrs by GTP using organic superacid catalysts (Scheme ) and characterize the obtained PRCrs.…”