|A Google-produced definition of physicochemical meaning of or relating to physics and chemistry or their overlapping joint subject of physical chemistry.|
The term “physico-chemical” tended to be used in the years circa 1870s to 1930/70s, after which the term “physical chemistry” tended to supersede the former; although not completely (the unwieldy phrase “physical chemical”, e.g., is inept in certain uses). The following Google-made term usage chronology outlines this:
Hmolscience thinkers to have employed "physicochemical" language, include: Henry Adams (1908-1909), Lawrence Henderson (1930s), Pitirim Sorokin (1943), in objection to Henderson, and the other physicochemically-minded thinkers of his historical "materialism school" (1928) classification, George Scott (1985), and Mirza Beg (1987).
The following are ripe quotes employing the term "physico-chemical" by American physical humanities historian Henry Adams:
“On the physico-chemical law of development and dynamics, our society has reached what is called the critical point where it is near a new phase or equilibrium.”— Henry Adams (1908), “Letter to Charles Gaskell” (Sep 27) 
“I’m looking for a ‘young and innocent physico-chemist [see: Henry Bumstead] who wants to earn a few dollars by teaching an idiot what is the first element of theory and expression in physics.”— Henry Adams (1908), “Note to John Jameson” (Dec) 
“My essay ‘The Rule of Phase [Applied to History]’ is a ‘mere intellectual plaything, like a puzzle’. I am interested in getting it into the hands of a ‘scientific, physico-chemical proofreader’ and I am willing to pay ‘liberally for the job’.”— Henry Adams (1909), Notes to Brooks Adams and John Jameson 
The following are other noted quotes:
“To a materialist no thing is real but atoms in a void and we are but molecular people controlled by the actions of natural physicochemical law.”— George Scott (1985), “Molecular People” dedicated to Lucretius
● Physicochemical humanities
1. (a) Adams, Henry. (1908). “Letter to Charles Gaskell”, Sep 27.
(b) Samuels, Ernest. (1989). Henry Adams (physico-chemical, pgs. 401, 411). Harvard University Press.
2. (a) Adams, Henry. (1908). “Note to John Jameson”, circa early Dec.
(b) Samuels, Ernest. (1989). Henry Adams (pg. 409). Harvard University Press.
● Physicochemical – Wikipedia.