Synthesis and Properties of Polyimides Containing Multiple Alkyl Side Chains

Abstract

A series of diamine monomers, i.e., 2,2′-bis{4-[3,4,5-tris(n-alkan-1-yloxy)benzoate]}-4,4′-biphenyldiamines containing multiple alkyl side chains, were synthesized in which the length of the alkyl side chains was varied from 5 to 18 carbon atoms. Polyimides were prepared from the diamines and pyromellitic dianhydride (PMDA), 3,3′4,4′-biphenyltetracarboxylic dianhydride (BPDA), 2,2′-dibromo-4,4′,5,5′-biphenyltetracarboxylic dianhydride (DBBPDA), and 2,2′-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), respectively, using a one-step method in 1,2-dichlorobenzene or 1-chloronaphthalene. Most of the polymers had good solubility in chlorinated solvents. Several copolyimides were prepared: BPDA, 2,2′-bis(trifluoromethyl)benzidine (PFMB), and C14 and C16 diamines. The solubility of copolyimides was dramatically affected by different monomer addition sequences. The high-molecular-weight polyimides could be solution cast into flexible, tough films except for those based on PMDA. The side chains that contained at least 10 carbon atoms crystallized. The melting points of the crystalline regions increased as the length of the side chains increased. Variable-temperature (VT) solid state 13 C nuclear magnetic resonance (NMR) showed that the polyimide containing C18 side chains crystallized at room temperature. A wide-angle X-ray diffraction (WAXD) study showed that the spacing between the main chains increased as the number of carbon atoms in the side chains increased. The diameter of aggregated backbones was 2.14 nm, indicating several polyimide main chains stacked each other to form supermolecular, nanoscale structures. Three polyimides and one copolyimide were used to prepare alignment layers. The films generated liquid crystal pretilt angles of 6, 9, 90, and 90°, respectively.

Synthetic 6FDA–ODA copolyimide membranes for gas separation and pervaporation: Functional groups and separation properties

“…M w =M n for 6FDAeODA, 6FDAe6ODAe4DBSA, 6FDAe8ODAe2DANT and 6FDAe 9ODAe1DANT are w1.1, and 1.30e1.43 for the others. The small values of M w =M n obtained from GPC probably resulted from the aggregation of polyimide chains in the polymerization solvent or in the GPC solvent [19].…”

Reversible organogels triggered by dynamic K+ binding and release

“…3,4,5-Tris(ndodecan-l-yloxy)benzohydrazide (5) was prepared as described in Refs. [47,48]. 2 0 ,3 0 -Isopropylidene guanosine (3) and 2 0 ,3 0 -Isopropylidene guanosine hemisuccinate (4) were prepared as described in Refs.…”

Effect of danling chain content on properties of 10-undecenoic acid-based polyurethane

“…When the danling chain is introduced into the polymer, the arrangement regularity between molecules will be disturbed so as to reduce the intermolecular stacking. So the glass transition temperature and the melting temperature of the polyurethane can be reduced [7,8] . When the vegetable oil with 6-18 C atoms chain react with the isocyanate, the introduction of dangling chain in the polyurethane will be realized.…”