Lab 5: Synthesis of a Superabsorbent Polymer Prelab Assignment-Due at the beginn
ID: 486155 • Letter: L
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Lab 5: Synthesis of a Superabsorbent Polymer Prelab Assignment-Due at the beginning of lab 1. Read this handout, Guide to Success in the Organic Chemistry Lab, and the Micropipet Instructions on Canvas before starting. 2. Print and complete the Prelab 5 Question Sheet, and turn in at the start of lab 3. Complete the following in your lab notebook IN PEN: a. Table of Contents: Find (or create) the Table of Contents at the front of the notebook: add the lab lab title, and the page for the first page of this lab report. b. Header information: Add to the top of the report's 1st page c. I. Introduction: Write this in your own words; do not copy this handout! d. II. Procedure: Write this in your own words; do not copy this handout! e. Ill. Results: Begin this section, ready to record observations. INTRODUCTION Many alkenes can be polymerized under free-radical conditions. Polymerization occurs more readily when the alkene contains a functional group that stabilizes the radical intermediate. Acrylic acid is an example of such an alkene monomer. The mechanism for the polymerization of acrylic acid involves two major steps: thermal initiation and propagation, as shown in Equations 1 and 2. A small amount of a free-radical initiator, a compound that can be induced to form radicals, is included in the reaction to get it started. In this case,VA-044 is the initiator The initiator radical adds to the C-C double bond of an alkene (acrylic acid) to form another radical. The resulting radical adds to another acrylic acid monomer to form a dimer, and so forth. The process can repeat itself many times, producing polyacrylic acid molecules containing up to millions of monomer units. The quantity of initiator used greatly affects the overall polymer product; very small amounts of initiator, enough to start only a relatively small number of polymer chains, favor high molar mass products. If large amounts of initiator were used instead, many small chains would begin, leading to large numbers of short chains. CH3 N N CH N. Equation 1 C-N N-C initiation) (VA-044) CO2H acrylic acid Equation 2 CH3 CH3 CO2H N propagation) n acrylic acidExplanation / Answer
Ans 3- if no MBA is used ,
The polymer absorbency depends on degree of cross-linking ,if no MBA used then there is no cross-linking of polymer hence it needs cross-linking to prevent the water solubility.
If lot more MBA used- MBA is cross-linking agent which neutralise the polymer cross-linking agent acts as a monomer in polymerization of another chain,chains are linked together,degree of cross-linking affects absorbance,more cross-linking will take place if more MBA used then less absorbance as polymer becomes rigid.
If more VA-044 used- it is azo initiator molecule which is water soluble in nature,if more used then many small chains would form leading to large number of short chains.for better absorbancy we need small number of polymer chains with high molar mass thus to get that we need less initiator VA-044.
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