Molecular weight control of polyacrylamide with sodium formate as a chain‐transfer agent: Characterization via size exclusion chromatography/multi‐angle laser light scattering and determination of chain‐transfer constant

Abstract

We discuss the synthesis and characterization of polyacrylamide (PAM) homopolymers with carefully controlled molecular weights (MWs). PAM was synthesized via free-radical solution polymerization under conditions that yield highly linear polymer with minimal levels of hydrolysis. The MW of the PAM homopolymers was controlled by the addition of sodium formate (NaOOCH) to the polymerization medium as a conventional chain-transfer agent. MWs and polydispersity indices (PDIs) were determined via size exclusion chromatography/multi-angle laser light scattering analysis; for polymerizations carried out to high conversion, PAM MWs ranged from 0.23 to 6.19 ϫ 10 6 g/mol, with most samples having PDI Ϸ2.0. Zero-shear intrinsic viscosities of the polymers were determined via low-shear viscometry in 0.514 M NaCl at 25°C. Data derived from the polymer characterization were used to determine the chaintransfer constant to NaOOCH under the given polymerization conditions and to calculate Mark-Houwink-Sakurada K and a values for PAM in 0.514 M NaCl at 25°C.

Improvement of the spatial frequency response of photopolymer materials by modifying polymer chain length

“…Full analysis and examination of this kinetic behavior, such as the rate of chain transfer (Gregg and Mayo method [14,29]), the reinitiation rate and the reinitiation efficiency are crucial to enable further control of chain locality. This study may eventually allow a clearer link between the nonlocal variance metric and the PA molecular weight to be found.…”

“…In this paper we aim to achieve this through the addition of a CTA into our simple standard material AA/PVA layers [1,6]. The CTA used in this study is sodium formate ͑HCOONa͒, which has a molecular weight of 68.01 g [13][14][15][16][17]. This CTA has the ability to stop the growth of a chain by yielding an atom to the active radical at the end of the growing chain.…”

Monomer diffusion rates in photopolymer material Part II High-frequency gratings and bulk diffusion

“…the polymerization process of AA [42]. Experimentally, it is convenient because it is a vapor at room temperature and can readily diffuse into and out of the polymer layer.…”

A Review of the Optimisation of Photopolymer Materials for Holographic Data Storage

“…In many polymerization systems, the average polymer weight is observed to be lower than predicted by the chain transfer reaction [13,[19][20][21]. Generally, the chain transfer process causes the premature termination of a growing macro-radical chain and arises because of the presence of a chain transfer agent (CTA) [13].…”