Effect of substituents upon melting points of linear polyesters

Abstract

Melting points were determined for several series of linear polyesters containing substituents either in the acid or glycol unit. The number of substituents was progressively increased by preparing copolyesters containing both unsubstituted and substituted glycol or acid units. The following systems were studied: (1) Those with trimethylene and 2‐methyltrimethylene glycols show decreasing melting points as the number of methyl groups is increased, because they introduce tetrahedral asymmetry. If the structrual unit is relatively short, crystallinity is completely destroyed. (2) Those with trimethylene and 2,2‐dimethyltrimethylene glycols show eutectic type melting point curves, since the substituent groups do not introduce asymmetry. The completely substituted polyesters have new crystal structures which give sharp X‐ray patterns. Those from short acids (C2–4) have higher melting points than the unsubstituted polyesters, while the others have lower melting points. The polyesters with an odd number of chain atoms in the unit have higher melting points than the even ones. The ability to pack closely into the crystal lattice appears to be important, a view supported by melting points of certain polyesters of β,β‐dimethylgultaric acid. (3) Those with trimethylene and 2‐methylenetrimethylene glycols and sebacic acid give a eutectic type curve, because of the appearance of a new crystal structure. (4) Those with succinic and α‐methylsuccinic acids and decamethylene glycol give progressively decreased melting points, decreased breaks in heating curves, and an increasingly distorted lattice as the number of methyl groups is increased, because random “head‐to‐head” and “head‐to‐tail” polymerization makes the completely substituted polyester irregular. (5) The polyester of d‐α,β‐dimethoxysuccinic acid and tetramethylene glycol is highly crystalline because the substituent groups are oriented in a regular manner. The meso‐polyester did not crystallize because of more random orientation of substituents. Decamethylene d‐tartrate similarly melts higher than the meso‐tartrate.

Crystallization‐induced reactions of copolymers. IV. Ester‐interchange reorganization of poly(ethylene terephthalate‐co‐2‐methylsuccinate)

“…The most effective reorganization of ti random copolymer toward a block copolymer was that for the 78.5% P(ET/ES) copolymer treated a t 220°C as discussed above. Sequence distribution information on comonomer units before and after treatment of this copolymer is given in Table I V in three forms as follows: (1) number-average sequence length of terephthalate units EnT; (2) Harwood run number R, which is a measure of the number of terephthalate blocks in every 100 repeating units and should decrease as block lcngth increases at. a given terephthalate c~n t e n t ;~ (3) the Theil Q factor, which is a measure of blockiness that has t.he advantage of being independent of copolymer composition6 (i.e., for a random copolymer, Q = 1 regardless of composition).…”

Constitutional Regularity in Linear Condensation Polymers

“…The fact that two regular polymers with different constitution can be prepared by simply changing the mode of monomer feed was shown first 3 2 in polyureas from bis(p-nitrophenyl) carbonate (7) and 2-(4-aminophenyl)ethylamine (8). Here the induction was shown to be very large or absent, depending on the first reactant; the relative reaction rate constants for (7) are ga~3.6 x 10-3 and gb~1.…”

“…Here the induction was shown to be very large or absent, depending on the first reactant; the relative reaction rate constants for (7) are ga~3.6 x 10-3 and gb~1. 02NOOC020 (7) H2NCH2CH20NH2 (8) Parenthetically it shall be noted here that attempts to control the constitution of polyesters by the same methods have also been made. Table 6 shows the results.…”

“…It is convenient to express the rate equations in terms of the dimensionless variables (7) Further simplification can be achieved by the introduction of a dimensionless time (J such that (8) For the specification of the mode and rate of addition of reactants to the polymerization mixture, two monomer feed functions need to be defined (9) such that Yand Z are the fractions of XabX and YccY respectively that have already been added to the reaction system. The system can then be represented by the following set of ordinary differential…”

Branched Diol Monomers from the Sequential Hydrogenation of Renewable Carboxylic Acids

“…As summarized in Figure 4, the addition of am ethyl substituent to either the diacid or diol had as ignificant impact on the thermal properties of the resulting polyester. [25,26] Whereas polybutylene succinate, the polymer resulting from the polymerization of succinic acid and 1,4-butanediol, is semicrystalline with am elting point of T m = 114 8C, the methyl-substituted polyesters were all fully amorphous with low glass-transition temperature values (T g below À35 8Cf or each sample).T hese soft, rubbery polyesters may be appropriate for numerousa pplications,including use in coatings,adhesives, sealants,elastomers, and foams. [27,28] As illustratedh ere as well as in previouse xamples, biomassderived feedstocks can be utilized in hybrid fermentation/thermocatalytic processes to produce drop-in replacementso re n- Figure 4.…”