User:Karlena L. Brown/Notebook/PVOH Research/2012/11/09

OBJECTIVES

• Prepare PVOH films for Acetylation Reactions
• Titrate PVOH film solutions

General Formula for reactions

Polyvinyl alcohol + [HoAc]→Polyvinyl acetate

Acetylation Reaction Protocol & Film Preparation

• In 10mL beaker, weigh out ~ 1.0 grams PVOH (MW 22K)
• Then, using a graduated cylinder add ~ 3-4 mL H₂O to the beaker
• After adding and combining PVOH (MW 22K) in a small beaker with H₂O, add a stir bar and prepare to stir solution
• On hot plate, stir and heat beaker solutions at 70-80°C for ~ 12 min or until PVOH dissolves
• Once PVOH solids thoroughly dissolve in solution, add a small portion of acetic acid (HoAc)
• In addition, add ~2 drops of HCl to the solution and continue to stir for an hour
• Allow the solution to cool and prepare for titration

REPEAT PROCEDURE ABOVE FOUR TIMES TO PREPARE FOUR FILMS

Acetylation Reaction Calculations

1:1 HoAc Reaction Ratio:

  MW R-CH2CHOH-R: 44.00 g/mol
  MW Acetic Acid (HoAc): 60.00 g/mol
  1.0g PVOH × (1 mol PVOH/44.00g PVOH) × (1 mol HoAc/1 mol PVOH) × (60.00g HoAc/1 mol HoAc) = 1.36g HoAc
  1.36g HoAc × (1mL HoAc/1.05g HoAc)= 1.30mL HoAc

20% HoAc Reaction Ratio:

  MW R-CH2CHOH-R: 44.00 g/mol
  MW Acetic Acid (HoAc): 60.00 g/mol
  1.0g PVOH × (1 mol PVOH/44.00g PVOH) × (0.2 mol HoAc/1 mol PVOH) × (60.00g HoAc/1 mol HoAc) = 0.27g HoAc
  0.27g HoAc × (1mL HoAc/1.05g HoAc)= 0.26mL HoAc

40% HoAc Reaction Ratio:

  MW R-CH2CHOH-R: 44.00 g/mol
  MW Acetic Acid (HoAc): 60.00 g/mol
  1.0g PVOH × (1 mol PVOH/44.00g PVOH) × (0.4 mol HoAc/1 mol PVOH) × (60.00g HoAc/1 mol HoAc) = 0.55g HoAc
  0.55g HoAc × (1mL HoAc/1.05g HoAc)= 0.52mL HoAc

60% HoAc Reaction Ratio:

  MW R-CH2CHOH-R: 44.00 g/mol
  MW Acetic Acid (HoAc): 60.00 g/mol
  1.0g PVOH × (1 mol PVOH/44.00g PVOH) × (0.6 mol HoAc/1 mol PVOH) × (60.00g HoAc/1 mol HoAc) = 0.82g HoAc
  0.82g HoAc × (1mL HoAc/1.05g HoAc)= 0.78mL HoAc

Titration Procedures & Solution Preparation

0.1M Sodium Bicarbonate (NaHCO₃)solution for titration preparation:

• Weigh out ~16.802g NaHCO₃

    (Actual NaHCO3 Mass= 16.8046g)

• Add the NaHCO₃ solids to a 250mL closed cap plastic bottle
• Next, add ~2500mL of H₂O to the bottle along with large magnetic stir bar
• Place container on a stir plate and stir solution for ~10 minutes until all solids dissipate

Notes

• Only the repeating unit of PVOH (22K) was focused upon when calculating % weight of HoAc additions to each solution (titration preparation)
• Molecular weight of repeating polyvinyl alcohol unit [C2H3OH] = 44.06g/mol

  1g PVOH(1 mol PVOH unit/44.06g PVOH) x (1 mol OH/1 mol PVOH)= 0.022696 mol PVOH

• In addition, the 1:1 HoAc ratio solution overheated by boiling; therefore, this solution was not used for the titration analysis.