Persulfate‐initiated polymerization of acrylamide

Abstract

A dilatometric technique was used to obtain conversion–time data for the polymerization of acrylamide initiated by potassium persulfate in water. The results are summarized by the empirical rate expression, −d[M1]/dt = Rp = k1.25[K2S2O8]0.5[M1]1.25, and k1.25 = 1.70 × 1011 exp {−16,900/RT} 1.0.75/mole−0.75‐min. Persulfate was varied over the range 9.5 × 10−4 to 5.2 × 10×2 mole/l., and initial monomer concentration [M1] was varied from 0.05 to 0.4 mole/l. The temperature range was 30−50°C. Results of analysis of the kinetics and energetics of the polymerization favor a cage‐effect theory rather than a complex‐formation theory to explain the order with respect to monomer.

Polyacrylic acid (poly-A) as a chelant and dispersant

“…13,14,26 Scott and Peppas 26 showed the unusual 3 ⁄2 dependence on monomer concentration at both acid and basic regimes, whereas the initiator dependence remains 1 ⁄2 during their studies on the kinetics of aqueous persulfate polymerization of acrylic acid. Ishige and Hamielec 27 and Riggs and Rodriguez 28 reported also a 3 ⁄2 dependence on monomer concentration for the case of aqueous persulfate polymerization of acrylamide. Cutie et al 12 also found that M n decreases at a high percent conversion and this result implies that the kinetic constants, especially, k d for initiation, are independent of conversion.…”

“…Based on the result that the kinetic constants are independent of conversion at pH ϳ 2, 26 M n should decrease at high conversion just as reported elsewhere. 12,27,28 At each HACA increase, the polymerization results in a Poly-A whose cumulative number average molecular weight is smaller than that originated from a lower concentration. On the other hand, M w increases when HACA increases; consequently, one would expect larger PDs with increases of HACA, just as our results concluded (see Fig.…”

“…This term is defined as the average number of monomer molecules polymerized per each radical that initiates a polymer chain, or, alternatively, it is the average number of steps of growth per effective radical. 10,11,28 The kinetic chain length depends of the ratio [monomer]/[initiator] 1/2 ; therefore, as HACA increases and the persulfate concentration is kept constant, we favor the formation of large-sized molecules. As explained earlier, large-size molecules will contribute more to M w than to M n .…”

Development of thermoresponsive poly(propylene-g-N-isopropylacrylamide) non-woven 3D scaffold for smart cell culture using oxyfluorination-assisted graft polymerisation

“…At elevated temperatures, the peroxide on the PP backbone is homolytically cleaved due to the low bond dissociation energy of the O-O bond to form alkoxy radicals (RO•) [29]. Conversely the APS initiator, which is also a peroxide, undergoes thermal decomposition to form sulphate radical ions (SO 4 •-) and hydroxyl radicals (OH•), which are capable of initiating polymerisation by adding to the unsaturated double bond of the NIPAAm monomer [30]. Finally, grafting of PNIPAAm onto the oNWF proceeds via coupling of the free radicals between the alkoxy radical (RO•) on the oNWF and the propagating chain of NIPAAm.…”

Modeling of two‐phase polymerization of acrylamide in aqueous poly(ethylene glycol) solution

“…Rodriguez et al 14 first observed a monomer dependence exceeding first-order in aqueous AM polymerization initiated by potassium persulfate (KPS). This was interpreted in terms of the AM monomer accelerating decomposition of the initiator.…”