A Caltech Library Service

Rational Approaches to Regulating Polymer Properties in Ring-Opening Metathesis Polymerization


Benedicto, Alto D. (1995) Rational Approaches to Regulating Polymer Properties in Ring-Opening Metathesis Polymerization. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/BC47-7W20.


The molecular weight distribution of a living polymerization when chain-transfer agents are intentionally added were computed numerically. Results showed that traditional expressions for number-average degree of polymerization (X̅n) and polydispersity index (PDI) of chain-growth polymerization cannot be used. The well-known Mayo equation fails even when the system has achieved steady-state polymerization. Although the behavior of the system is complex, an analytical expression for X̅n was derived. Plots based on the analytical expression showed excellent agreement with that from numerical solutions. The implications of the calculations were discussed. The kinetics of living ring-opening metathesis polymerization (ROMP) of norbornene in the presence of neohexene catalyzed by Mo was investigated.

The living ROMP of norbornene (n̲) and bicyclo[3.2.0]hept-2-ene (c̲) by Cl₂(PPh₃)₂Ru(=CHCHCPh₂) was demonstrated. The molecular weight varied linearly with conversion. Discrete propagating species showed that PPh₃ ligand dissociated during polymerization of c̲, and that CuCl (abstracts PPh₃) enhanced the rate of polymerization of n̲. The specific propagation rate constants (kn̲n̲ and kc̲c̲, respectively) of homopolymerization of n̲ and c̲ were measured, respectively. Block copolymers were easily prepared. From reactivity ratio studies, the ordering of the specific propagation rate constants are kn̲c̲ >> kkn̲n̲ > kc̲c̲ > kc̲n̲. The effect of styrene as chain-transfer agent on the molecular weight was examined.

The hitherto unassigned (and unknown) microstructure of polymers prepared from 7-oxabicyclo[2.2.1]hept-2-ene derivatives have finally been unambiguously assigned. Polymers catalyzed by W(CH-t-Bu)(NAr)(OCMe(CF₃)₂)₂ have all cis double bonds and highly syndiotactic, while those from RuCl₃•3H₂0 and [RuCl(μ-Cl)(μ³:μ³-C₁₀H₁₆)]₂ {C₁₀H₁₆= 2,7-dimethyloctadienediyl} have high trans double bond content and highly isotactic.

Studies on the olefin isomerization catalyzed by Ru(H₂O)₆tos₂ revealed that the presence of hydroxyl functionality on the terminal olefin resulted in formation of 1:1 ratio of cis : trans double bonds on the isomerized internal olefin product, in contrast with near exclusive isomerization of double bond to trans when no hydroxyl group was present.

A numerical algorithm was developed for the evaluation of a chirality function for triangles on a plane, showing that such algorithm may be easily extended into the case of tetrahedron in 3-dimensional space.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Xn, chain transfer, degree of polymerization, living polymerization, ruthenium, microstructure, double bond migration
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Grubbs, Robert H.
Thesis Committee:
  • Grubbs, Robert H. (chair)
  • Dougherty, Dennis A.
  • Bercaw, John E.
  • Lewis, Nathan Saul
  • Wang, Zhen-Gang
Defense Date:15 June 1994
Record Number:CaltechETD:etd-09112007-131436
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:3471
Deposited By: Imported from ETD-db
Deposited On:17 Sep 2007
Last Modified:13 Jan 2020 18:17

Thesis Files

PDF - Final Version
See Usage Policy.


Repository Staff Only: item control page