Preparation Of Acrylamide Polymer Particles By Self-stabilized Precipitation Polymerization

Acrylamide polymers have a very wide range of applications due to their unique properties.The conventional polymerization methods for the preparation of acrylamide polymers often require the addition of a large amount of stabilizers or dispersants,relatively complex post-treatment procedure,or special equipment and complicated process which are difficult for large-scale industrial production.In order to overcome the above-mentioned problems,a simple and efficient method for the preparation of acrylamide polymers was proposed based on self-stabilized precipitation polymerization(2SP)technology.Through the adjustment of reaction medium,monodisperse acrylamide terpolymer and homopolymer microspheres with well-defined morphology were successfully prepared.The effects of polymerization parameters,including monomer concentration,reaction time,and monomer feed ratio on the surface morphology and chemical composition of the resultant polymer particles were explored in detail,and the following are the main research contents:1.The common monomer pair of styrene(St)and maleic anhydride(MAH)for 2SP process,were chosed to conduct terpolymerization with AM in order to adjust the solubility parameters of the copolymer.Isoamyl acetate(IPA)was selected as the suitable reaction medium to prepare Poly(St/MAH/AM)microspheres with well-defined morphology and uniform size.The results of FT-IR and 13C NMR confirm the existence of St,MAH and AM in obtained terpolymer and the sequence structure of the terpolymer.2.The effects of polymerization parameters including monomer concentration,reaction time and monomer feed ratio on the morphology and chemical composition of the terpolymer particles were explored systematically.The experimental results show that the size of the polymer microspheres increased dramatically with increasing monomer concentration.When the molar feed ratio of[St]/[MAH]/[AM]was 1/1/1,the size of the resultant poly(St/MAH/AM)microspheres increased sharply from 357 nm to 2114 nm as the monomer concentration increasing from 10 wt%to 30 wt%.3.A simple method for determination of the chemical composition of the poly(St/MAH/AM)terpolymers was established based on gas chromatography(GC).The effects of monomer feed ratio on the terpolymer composition was explored.It is found that the terpolymer composition was close to the initial monomer molar feed ratio and kept almost constant during the whole polymerization process when with equivalent molar ratio of[St]/[MAH].4.Kinetic of the terpolymerization of St/MAH/AM was investigated,and the terpolymerization behavior and variation of terpolymer composition at different monomer feed ratios were determined through the calculation of activation energy,frequency factor and initial polymerization rate.5.Monodisperse polyacrylamide(PAM)microspheres were prepared in DMAc and DMF by 2SP process,and the effect of monomer concentration on the morphology of PAM microspheres and the particle formation mechanism were explored.With the addition of crosslinking agent N,N-methylenebisacrylamide(MBA),crosslinked PAM microspheres were successfully obtained via 2SP process.The diameter of the as-formed crosslinked microspheres increased with increasing feed ratio of MBA,and the particles became larger but irregulation upon coagulation.When the feed ratio of MBA was 0.5 wt%relative to the monomer,crosslinked PAM microspheres with uniform size and good dispersity can be prepared.Core-shell microspheres with crosslinked PS shell layer could be prepared via template method,with PAM microspheres as template cores and DVB as the crosslinker.The successful preparation of the core-shell structure was confirmed by SEM,TEM,and XPS.