Modified polymers from CIS‐1,4‐polyisoprene

Abstract

Chemical transformation of functional groups in polymers has often been used as a method to prepare polymers with specific properties (1). Polymer-analogous reactions with polydienes have been described (2,3) and recently we reported on the chemical modification of polyisoprenes (43). By addition of chlorosulfonyl isocyanate (CSI) to C% bonds, modified polyisoprenes were obtained with N-chlorosulfonyl p-lactam and 0, y-unsaturated N-chlorosulfonyl carbonamide groups. A second-step modification by reaction with NaOH resulted in the formation of water-soluble polyelectrolytes with anticoagulant activity (5-7).are presented which give information about the chemical structure of the modified polymers.This article deals with the modification of cis-l,4-polyisoprene and results ExperimentalSolutions of cis-l,4-polyisoprene (Cariflex IR 307, cis content more than 96%) in toluene (0.2M) were added to stirred solutions of CSI in the same solvent. Reactions were carried out at 0 or 20°C in a nitrogen atmosphere. After 1 hr the solid cis-l,4-polyisoprene-CSI adducts were isolated and washed with diethylether. Polyelectrolytes were synthesized from these adducts by heating with 2M NaOH for 1 hr. Subsequently they were precipitated by pouring the alkaline solutions in ethanol.More experimental details have been published elsewhere (43). Results and DiscussionThe reaction of cis-l,4-polyisoprene with CSI (Scheme I) leads to the formation of a modified polymer with predominantly structure a, whereas structure b is also formed (43). It was found that with a 50% molar excess of CSI, addition takes place to an extent of 65% at 20°C (Table I , exp. 1). The degree of addition decreases by lowering the temperature, as can be seen from the results of exp. 2. The effect of a prolonged reaction time (6 hr) is supposed to be of minor importance, because an increase of the reaction time (exp. 3) does not lead to an increase of the degree of addition (cf. also the results of exps. 5 and 6). The effect of an increase of the CSI:cis-l,4-polyisoprene molar ratio, on the other hand, is apparent, as can be seen from the results of exps. 3 and 4.

Synthetic polymer sulphonated polyisoprene as a universal anticoagulant for laboratory testing

“…SPIPs were first synthesized by van der Does et al and were found to have strong anticoagulant activity (1,10,11). The precise mechanism of this SPIP activity is not well understood.…”

Synthetic heparinoids labelled with 125I and 35S

“…200 mg of partially desulfated polyelectrolyte was dissolved in 4 r n l water and the solution was adjusted to pH = 9.5 by the addition of 1 M NaOH. Then the solution was heated to 5…”

“…In previous publications (1)(2)(3)(4)(5)(6)(7) we reported on the preparation of a water-soluble polyelectrolyte having anticoagulant activity (2)(3)(4)6,7). Thepolyelectrolyte is derived from cis-lI4-polyisoprene and contains the following structural units, apart from unreacted 0362-4803 /82 /lo125 1-1 3$01.30 0 1982 by John Wiley & Sons, Ltd.…”

Comparison of two carboxylate‐activating agents for the modification of a synthetic heparinoid polyelectrolyte

“…Materials the method described previously (7,8 Dialysis tubing: Benzoylated dialysis tubing (Sigma D 7884) was used for the dialysis of solutions of PLE-L, and unmodified dialysis tubing (Cenco) was used for the dialysis of solutions of PLE-H.…”