The phase behavior of a polymer network obtained by moderately crosslinking a segmented-chain liq. cryst. polymer is presented. The network is formed by reacting H2NC6H4-p-O(CH2)6O-p-C6H4NH2 with an o-dichlorobenzene soln. of a polyester previously prepd. by reaction of 2,5-dihydroxybenzaldehyde with ClOCC6H4-p-O(CH2)10O-p-C6H4COCl. The network shows thermotropic nematic behavior of a cybotactic type as obsd. for the linear polymer. However, the mesophase stability is significantly reduced. The origin of this redn. is discussed and related to the intrinsic decrease of the mesogenic potential of the linear chains forming the network. The phase behavior of the swollen network is also examd. The formation of a noncryst. anisotropic gel at temps. lower than ∼80° is obsd. with a polymer/solvent wt. ratio range of 0.065-0.080. Isotropization takes place on heating and is accompanied by an enthalpic increase. The 1H-NMR spectrum of the anisotropic gel suggests that the gel has a biphasic structure rather than a lyotropic single structure.
Phase behavior of a network polymer based on a segmented-chain polymeric mesogen
PRAGLIOLA, Stefania;
1993-01-01
Abstract
The phase behavior of a polymer network obtained by moderately crosslinking a segmented-chain liq. cryst. polymer is presented. The network is formed by reacting H2NC6H4-p-O(CH2)6O-p-C6H4NH2 with an o-dichlorobenzene soln. of a polyester previously prepd. by reaction of 2,5-dihydroxybenzaldehyde with ClOCC6H4-p-O(CH2)10O-p-C6H4COCl. The network shows thermotropic nematic behavior of a cybotactic type as obsd. for the linear polymer. However, the mesophase stability is significantly reduced. The origin of this redn. is discussed and related to the intrinsic decrease of the mesogenic potential of the linear chains forming the network. The phase behavior of the swollen network is also examd. The formation of a noncryst. anisotropic gel at temps. lower than ∼80° is obsd. with a polymer/solvent wt. ratio range of 0.065-0.080. Isotropization takes place on heating and is accompanied by an enthalpic increase. The 1H-NMR spectrum of the anisotropic gel suggests that the gel has a biphasic structure rather than a lyotropic single structure.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
