EFFECT OF SEQUENCE STRUCTURE ON THE THERMOTROPIC LIQUID CRYSTALLINE PROPERTIES OF POLYESTERAMIDES BASED ON DIMETHYLBENZIDINE, BISPHENOL-A AND ρ-TEREPHTHALYL CHLORIDE

A series of thermotropic liquid crystalline polyesteramides with differ-ent sequence structure based on dimethylbenzidine (DMBD), bisphenol-A(BPA) and p-terephthalyl chloride (TPC) was synthesized by changing the feeding order of monomers inlow temperature solution polycondensation system. By means of NMR and a computer pro-gram the sequence structure parameters were measured. The effect of sequence structureon liquid crystalline phase transition temperature of PEAs obtained was investigated.

SYNTHESIS AND CHARACTERIZATION OF BIODEGRADABLE POLYESTERAMIDES CONSTRUCTED MAINLY BY ALTERNATING DIESTERDIAMIDE UNITS FROM N,N'-BIS(2-HYDROXYETHYL)-ADIPAMIDE AND DIACIDS

Two kinds of aliphatic alternating polyesteramide prepolymers were prepared through melt polycondensation from N,N＇-bis（2-hydroxyethyl）-adipamide and adipic acid or sebacic acid. Chain extension of them was conducted with 2,2＇-（1,4- phenylene）-bis（2-oxazoline） and adipoyl biscaprolactamate as combined chain extenders. The chain extended polyesteramides （ExtPEAs） were characterized by IR, 1H-NMR, differential scanning calorimetry, thermogravimetric analysis, wide angle X-ray scattering, tensile test and enzymatic degradation. The results showed that the ExtPEA（4,m）s were mainly constituted with the diester adipamide alternating units. ExtPEA（4,4） and ExtPEA（4,8） had Tm of 83.8℃ and 85.8℃ and initial decomposition temperature above 310.0℃. They crystallized similarly as Nylon-66 did and were flexible thermoplastic materials with tensile strength up to 25.64 MPa and strain at break up to 737%.

Synthesis and Characterization of Biodegradable Alternating Polyesteramides from Mixed Diamidediols and Sebacic Acid

A series of polyesteramide prepolymers[PrePEA（0/4,8）s] having mixed alternating bisesterdiamide units was synthesized via melt polycondensation from N,N＇-bis（2-hydroxyethyl）oxamide（0） and N,N＇-bis（2-hydroxyethyl）-adipamide（4） with sebacic acid（8） at different molar ratios.Chain extension of them was conducted with 2,2＇-（1,4-phenylene）-bis（2-oxazoline） and adipoyl biscaprolactamate as combined chain extenders.The chain extended polyesteramides[ExtPEA（0/4,8）s] were characterized by proton nuclear magnetic resonance（1H NMR）,gel permeation chromatography（GPC）,differential scanning calorimetry（DSC）,thermogravimetry analysis（TGA）,wide angle X-ray scattering,tensile test and enzymatic degradation.The results show that ExtPEA（0/4,8）s were crystalline polyesteramides.They had Tm up to 136.5 ℃ and initial decomposition temperature above 297.5 ℃.They crystallized in similar crystallites into Nylon-66 and degraded under the catalysis of protease or lipase.They are thermoplastic materials with tensile strength up to 21.5 MPa and elongation at break above 64.0％.

A Novel Guided Bone Regeneration Membrane Composed of Nano-hydroxyapatite and Aliphatic Polyester-amide

Hydrothermally synthesized nano-hydroxyapatite（n-HA ） varmg m wetght Jrom 10% to 30% was used us filler to make guided bone regeneration （ GBR ） composite membranes with navel aliphatic polyesteramide （ PEA ）. The structare and properties of PEA and its n- HA composites were investigated through TEM, IR, XRD, SEM and EDX. The shape and size of the n- HA crystals are similar to the apatite crystals in nataral bone. Molecule interactions are present between the n- HA and PEA in the compasite, which allows the uniform dispersion of n- HA in PEA matrix. This contributes enhanced mechanical property and bioactivhy to the compasite. The cytacompatibilhy of the composites has been investigated by culturing osteoblasts on the membranes. Good cell attachment and proliferation manner were observed on the membranes after 1 week. These results suggest that the PEA/ n-HA compasite membrane prepared in this study may serve us barrier membranes for guided bone regeneration and potential candidate scaffold for tissue engineering.

SYNTHESIS AND PURIFICATION OF N,N'-E1S(P-CARBOMETHOXYBENZOYL)BUTANEDIAMINE(T4T-DIMETHYL)

T4T-dimethyl is commonly employed as hard segment when polyesteramide is produced. Polyesteramide is one of thermoplastic elastomers, like polyurethane which is composed of two different types of segments, usually referred to as soft and hard segments. The characters of hard segment have much influence on the properties of the polymer. To get the polyesteramide with high order, it is desirable to make T4T-dimethyl pure. In this paper, how to synthesize, to purify as well as to detect the purity of T4T-dimethyl are described in detail.